Name Designation Affiliation Date Signature

Submitted by:

G D Harris Site Engineer and Power Specialist

SPDO 10/11/11

Accepted by:

R P Millenaar Chief Site Engineer

SPDO 10/11/11

Approved by:

R T Schilizzi Director SPDO 10/11/11

SUMMARY REPORT ON SITE PHYSICAL CHARACTERISTICS

Document number ................................................................... WP3-060.040.010-FR-001 Revision ........................................................................................................................... B Author .................................................................................... R.P. Millenaar, G. D. Harris Date ................................................................................................................. 2011-11-10 Status ..............................................................................................................Confidential

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DOCUMENT HISTORY Revision Date Of Issue Engineering Change

Number

Comments

A 10-11-2011 - First draft

B 10/11/2011 - Released

DOCUMENT SOFTWARE Package Version Filename

Wordprocessor MsWord Word 2007 Report on Site Physical Characteristics 0.70

Block diagrams

Other

ORGANISATION DETAILS Name SKA Program Development Office

Physical/Postal

Address

Jodrell Bank Centre for Astrophysics

Alan Turing Building

The University of Manchester

Oxford Road

Manchester, UK

M13 9PL

Fax. +44 (0)161 275 4049

Website www.skatelescope.org

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TABLE OF CONTENTS

1 Introduction .............................................................................................................................................. 9

2 Scope ........................................................................................................................................................ 9

3 The Request for Information ..................................................................................................................... 9

4 Information supplied .............................................................................................................................. 12

4.1 Overview ................................................................................................................................................. 12 4.1.1 Australasia....................................................................................................................................... 12 4.1.2 Southern Africa ............................................................................................................................... 13

4.2 Environmental ........................................................................................................................................ 14 4.2.1 Temperature ................................................................................................................................... 15 4.2.2 Humidity ......................................................................................................................................... 16 4.2.3 Rainfall ............................................................................................................................................ 19 4.2.4 Dewpoint ........................................................................................................................................ 23 4.2.5 Ice, hail and pooling ........................................................................................................................ 25 4.2.6 Cloud cover ..................................................................................................................................... 26 4.2.7 Wind ................................................................................................................................................ 28 4.2.8 Solar radiation ................................................................................................................................. 34 4.2.9 Airborne particles and chemicals .................................................................................................... 35 4.2.10 Animals, insects and birds ............................................................................................................ 35 4.2.11 Restrictions in use ......................................................................................................................... 36 4.2.12 Wildfires ........................................................................................................................................ 36 4.2.13 Seismic stability ............................................................................................................................ 37

4.3 Severe weather ....................................................................................................................................... 38 4.3.1 Thunderstorms and lightning .......................................................................................................... 38 4.3.2 Strong winds, cyclones, tornados ................................................................................................... 40 4.3.3 Storm cells....................................................................................................................................... 43 4.3.4 Large hail events ............................................................................................................................. 43 4.3.5 Flooding, flash flood occurrence ..................................................................................................... 44 4.3.6 Dust storms ..................................................................................................................................... 44

4.4 Geotechnical ........................................................................................................................................... 45 4.4.1 Sub-surface strata ........................................................................................................................... 45 4.4.2 Water table ..................................................................................................................................... 48 4.4.3 Subsurface conductivity profile ...................................................................................................... 48 4.4.4 Surface and subsurface temperatures ............................................................................................ 49

5 Information supplied for stations outside the core ................................................................................. 51

5.1 Overview ................................................................................................................................................. 51 5.1.1 Australia .......................................................................................................................................... 51 5.1.2 South Africa..................................................................................................................................... 51

5.2 Environmental ........................................................................................................................................ 52 5.2.1 Temperature ................................................................................................................................... 52 5.2.2 Humidity ......................................................................................................................................... 53 5.2.3 Rainfall ............................................................................................................................................ 54 5.2.4 Dewpoint ........................................................................................................................................ 55 5.2.5 Ice, hail and pooling ........................................................................................................................ 56 5.2.6 Cloud cover ..................................................................................................................................... 58 5.2.7 Wind ................................................................................................................................................ 58 5.2.8 Solar Radiation ................................................................................................................................ 60

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5.2.9 Airborne particles and chemicals .................................................................................................... 61 5.2.10 Animals, insects and birds ............................................................................................................ 61 5.2.11 Restrictions in use ......................................................................................................................... 62 5.2.12 Wildfires ........................................................................................................................................ 63 5.2.13 Seismic stability ............................................................................................................................ 64

5.3 Severe weather ....................................................................................................................................... 65 5.3.1 Thunderstorms and lightning .......................................................................................................... 65 5.3.2 Strong winds ................................................................................................................................... 65 5.3.3 Storm cells....................................................................................................................................... 66 5.3.4 Large hail events ............................................................................................................................. 66 5.3.5 Flooding, flash flood occurrence ..................................................................................................... 66 5.3.6 Dust storms ..................................................................................................................................... 68

5.4 Geotechnical ........................................................................................................................................... 68 5.4.1 Sub-surface strata ........................................................................................................................... 68 5.4.2 Water table ..................................................................................................................................... 68 5.4.3 Subsurface conductivity profile ...................................................................................................... 71 5.4.4 Surface and subsurface temperatures ............................................................................................ 71

6 References .............................................................................................................................................. 72

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FIGURES Figure 1: Average daily mean temperature (annual), overlaid with SKA array stations. ...................................... 15 Figure 2: Statistics for temperature data, collected in the period 01/01/2005 to 31/03/2011, indicating the

following: mean, range (average of maximum - minimum daily temperature), average maximum and minimum over the days of the month, absolute maximum and minimum over the days of the month, and average and maximum rate of variation over one hour timescales. ................................................. 15

Figure 3: Graph of Maximum and Minimum Daily Temperatures (SA data processed from original weather station data; Aus data plotted from tabulated summary in report) ......................................................... 16

Figure 4: Chart illustrating daily variation in temperature for the first day of each month in 2010 (SA data processed from original weather station data; Aus data plotted from tabulated summary in report) .... 16

Figure 5: Average daily relative humidity (annual), overlaid with SKA array stations. ......................................... 17 Figure 6: Statistics for humidity data, collected in the period 01/01/2005 to 31/03/2011, indicating the

following: mean, range (average for maximum – minimum daily relative humidity), average maximum and minimum over the days of the month, and absolute maximum and minimum over the days of the month. ....................................................................................................................................................... 17

Figure 7: This graph shows the mean relative humidity at the two core sites at 9am and at 3pm. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied). ........................................................................... 18

Figure 8: Range of mean humidity (%) is given for 9am and 3pm for the two core sites. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied). .................................................................................. 18

Figure 9: Average rainfall (annual), overlaid with SKA array stations. ................................................................. 19 Figure 10: Statistics for rainfall data, collected in the period 01/01/2005 to 31/03/2011, indicating the

following mean per day, absolute maximum daily rainfall over the days of the month, and absolute maximum rainfall in a 30 minute burst in that month. ............................................................................. 19

Figure 11: The mean number of rainy days for each of the core sites. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied). .............................................................................................................................. 20

Figure 12: Mean rainfall for both core sites. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied). ................................................................................................................................................................... 20

Figure 13: The minimum average monthly rainfall. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied). .............................................................................................................................. 21

Figure 14: The 2010 rainfall for both core sites is plotted together with the SA average rainfall for October 2005 to March 2011. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the Absolute Maximum Daily Rainfall (Table 13 in the submission). .............................................................. 21

Figure 15: The highest daily rainfall in a given month. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied). .............................................................................................................................. 22

Figure 16: The maximum total monthly rainfall. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied). ................................................................................................................................................... 22

Figure 17: The daily rainfall in Australia in 2010 overlaid with the maximum rainfall on any one day in SA between 27

th September 2005 and 2

nd April 2011. The SA plot has been calculated from the raw data

files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the Absolute Maximum Daily Rainfall (Table 13 in the submission).......... 23

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Figure 18: The average dewpoint temperatures at the MRO; All Years (see section 4.1.1 in Information Supplied). ................................................................................................................................................... 23

Figure 19: Statistics for derived dewpoint data, collected in the period 01/01/2005 to 31/03/2011, indicating the following: mean, range (average of maximum – minimum daily derived dewpoint), average maximum and minimum over the days of the month, and absolute maximum and minimum over the days of the month. .................................................................................................................................... 24

Figure 20: The mean, range (average of maximum – minimum daily derived dewpoint), average maximum and minimum over the days of the month, and absolute maximum and minimum over the days of the month for both sites. The SA plot has been taken from Annexure F6.4 which summarises data files which span from October 2005 to March 2011. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied). ................................................. 24

Figure 21: Inundation layer from South African 1:250,000 topographic series. This layer indicates areas that are subject to saturation, and hence pooling of water. .................................................................................. 25

Figure 22: Number of frost days per year. This indicates around 33 frost days per year but this is typically early morning and does not persist throughout the day. .................................................................................. 26

Figure 23: Average monthly cloud cover at the MRO; All Years (see section 4.1.1 in Information Supplied). ..... 26 Figure 24: Clear skies analysis for Van Wyksvlei and Brandvlei (58km and 96km from SKA Core site respectively)

................................................................................................................................................................... 27 Figure 25: Graph of Cloud Coverage The SA plot has been replicated from the South African 2005 SKA Bid

Submission data (SA Annexures F1.1 and F1.2) which spans from 1995 to 2004 overlaid with cloud cover data given in Table 15 of the Australian report; All Years (see section 4.1.1 in Information Supplied). ... 27

Figure 26: Graph showing an overview of the wind characteristics of both core sites (m/s). The SA plot has been plotted from the data file in Annexure F6.6 which spans from 01/01/2005 to 31/03/2011. The Australian data is plotted from the data in tables 16, 17, 18 and 19 in the report from “All Years” (see section 4.1.1 in Information Supplied). ..................................................................................................... 28

Figure 27: Windroses for both core locations. ..................................................................................................... 33 Figure 28: Solar radiation; daily average, maximum monthly average and minimum monthly average. The SA

data has been plotted from the data files in Annexure F6.7 which span from 15/10/2004 to 05/07/2011. The Australian data is taken from table 20 in the report from “All Years” (see section 4.1.1 in Information Supplied). .............................................................................................................................. 34

Figure 29: Aerosol Optical Thickness (AOT), as measured in summer and winter at the SKA core and skirt region in 2007. The global mean is provided for comparative purposes. ............................................................ 35

Figure 30: Earthquake epicentre locations, overlaid with SKA array stations. ..................................................... 37 Figure 31: Seismic events, as recorded between 1973 and 2003 at the National Earthquake Information Centre,

operated by the US Geological Survey. ..................................................................................................... 37 Figure 32: This map shows the number of annual thunder-days. Most remote stations “are subject to less than

20 thunder days per year”, with the exception of some stations in Northern and Eastern areas. ........... 38 Figure 33: This map shows the annual lightning ground flash density. For most states a density of 1 per square

kilometre per year is reported, for Eastern states 2 to 3 km-2

yr-1

. Northern areas have significantly higher density, but no remote station ...................................................................................................... 38

Figure 34: Annual lightning strike frequencies per square kilometre, averaged over the period 1975 to 1986. The contours are for lightning flashes per km

2. Note that on this map the remote stations are for the

2005 submission, which does not quite correspond to the current planned locations. ........................... 39 Figure 35: Annual lightning strike frequencies per km

2 for the year 2002 in Southern Africa. ............................ 39

Figure 36: Australian Government BOM public information on tropical cyclone traces, over a 100 year period. Figure retrieved from BOM website; not from submitted document....................................................... 40

Figure 37: Worldwide tropical cyclones over the years 1945 to 2006. Note that all tracks across the Australian continent are classified as tropical storms or depressions, in line with the assessment that these are dissipating cyclones. [Source: http://en.wikipedia.org/wiki/File:Tropical_cyclones_1945_2006_wikicolor.png retrieved 10/11/2011]. ................................................................................................................................................................... 41

Figure 38: Classification of the Australian continent in wind regions. ................................................................. 41 Figure 39: Average number of strong winds at the MRO, based on BOM data over an unspecified number of

years. The submission document states that “similar averages are experienced over the entire 180 km region.” ...................................................................................................................................................... 42

Figure 40: Detailed view of tropical cyclones traces (1980-2005). This graph from publicly available sources; not extracted from submission document. [Source:

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http://upload.wikimedia.org/wikipedia/commons/2/23/Global_tropical_cyclone_tracks-edit2.jpg retrieved 10/11/2011]. .............................................................................................................................. 43

Figure 41: Typical ground profile at the core. ...................................................................................................... 45 Figure 42: Geological survey map, indicating lithographic classes of rock structure. .......................................... 46 Figure 43: Subsurface pH map for the Core site, which can be used as a proxy for corrosive minerals. An

average pH value of 8.4 is recorded across the Core and Skirt region. ..................................................... 47 Figure 44: Monthly surface and subsurface temperatures for the MRO. No monthly maxima have been

provided for surface temperatures. .......................................................................................................... 49 Figure 45: “Theoretical and measured scaling of diurnal temperature variation, as function of soil depth. The

resolution of the measurement sensors exceeds the temperature variation below depths of 0.5m. Measurement data below 0.5 m in depth is therefore not used to determine the fitted model.” .......... 50

Figure 46: Spiral Arms with associated weather stations *The following figures use the term “All Weather Stations” meaning all the weather stations mapped on this diagram] ..................................................... 52

Figure 47: Temperature summary throughout all weather stations. ................................................................... 52 Figure 48: The relative humidity throughout all weather stations ....................................................................... 53 Figure 49: Rainfall summary throughout all weather stations ............................................................................. 54 Figure 50: Summary of dewpoint throughout all of the weather stations ........................................................... 55 Figure 51: Annual number of frost days ............................................................................................................... 56 Figure 52: Hail frequency map of South Africa ..................................................................................................... 57 Figure 53: Pooling of water for the central region ............................................................................................... 57 Figure 54: Annual bright sunshine hours for the core, spiral arms and remote stations ..................................... 58 Figure 55: Wind speed during summer months, overlaid with SKA array-stations. ............................................. 58 Figure 56: Wind speed during winter months, overlaid with SKA array-stations. ................................................ 59 Figure 57: REM-10 Wind Speed Data ................................................................................................................... 59 Figure 58: REM-10 Wind Direction Data ............................................................................................................... 60 Figure 59: Average daily solar exposure (annual), overlaid with SKA array-stations. .......................................... 60 Figure 60: Solar radiation summary for all weather stations ............................................................................... 61 Figure 61: 2007 AOT at 550nm for SKA sites ........................................................................................................ 61 Figure 62: Map of South Africa overlaid with South African National Parks (SANPARKS) and SKA array

configuration ............................................................................................................................................. 62 Figure 63: Restrictions due to indigenous use - Northern Cape ........................................................................... 62 Figure 64: Remote stations with active fires 2010 ............................................................................................... 63 Figure 65: Active fires 2010 - Core and spiral arms .............................................................................................. 64 Figure 66: Seismic activity .................................................................................................................................... 64 Figure 67: Lightning and ground flash density at South African and nearby African remote stations. ................ 65 Figure 68: Tropical storm tracks over Madagascar, 1999-2011 ........................................................................... 66 Figure 69: Flooding ............................................................................................................................................... 67 Figure 70: Mean annual run-off of South Africa ................................................................................................... 67 Figure 71: Subsoil pH levels of South Africa ......................................................................................................... 68 Figure 72: Bore hole water quality and flow rate ................................................................................................. 70 Figure 73: Surface Conductivity map for the SKA site .......................................................................................... 71

TABLES Table 1: Overview of information supplied, Australasia....................................................................................... 12 Table 2: Australian weather stations: locations and reporting period. ................................................................ 12 Table 3: Overview of information supplied, Southern Africa ............................................................................... 14 Table 4: Wind speed conversions ......................................................................................................................... 33 Table 5: Surface strata lithology for Australian core site...................................................................................... 45 Table 6: Surface strata lithology for South African core and skirt regions ........................................................... 47 Table 7: African remote station temperature information, for the year 2010. .................................................... 53 Table 8: African remote station relative humidity information, for the year 2010. ............................................. 54

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Glossary AA Aperture Array

AGA Astronomy Geographic Advantage (Act), South Africa

AOT Aerosol Optical Thickness

ARC-ISCW Agricultural Research Council Institute for Soil, Climate and Water (South Africa)

BOM Bureau of Meteorology (Australia)

DEM Digital Elevation Model

EIA Environmental Impact Assessment report (South Africa MeerKAT)

EMI Electro Magnetic Interference

KAT Karoo Array Telescope

MODIS Moderate Resolution Imaging Spectroradiometer

MRO Murchison Radio Observatory

MWA Murchison Widefield Array

NRF National Research Foundation (South Africa)

PAF Phased Array Feed

RfI Request for Information

RFI Radio Frequency Interference

SASPO South African SKA Project Office

SAWS South African Weather Service

SKA Square Kilometre Array

SPDO SKA Program Development Office

SSEC SKA Science and Engineering Committee

SSG SKA Siting Group

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1 Introduction

Physical characteristics found at the future site for the Square Kilometre Array have a considerable impact on the design of telescope structures and electronics, reliability and maintenance strategies, capital expenditures and operating cost. These characteristics fall in three categories:

1. Environmental: climate data such as wind, rain and temperature; 2. Severe weather: exceptional events, for which appropriate protective measures must be

built into the system and procedures; 3. Geophysical/-technical: conditions affecting foundations, construction, trenching for power

and fibre. Information on these topics has been gathered by the SPDO over the past three years within PrepSKA WP3.6 on Physical Site Characteristics, see [1]. For the site selection process the SSG has issued a Request for Information (RfI), [2], in which the two candidate hosts were invited to supply information also on the physical characteristics at their proposed sites. In this document the proponent’s responses to the RfI are summarized in a format that facilitates comparison of data.

2 Scope

The Request for Information has targeted the full SKA configuration, i.e. Phase 2 which extends over areas 3000km distant or more. The majority of the receptors are situated in a small central area, measuring 180km in radius, centred on the location of the ‘core’: Boolardy Station in Western Australia and Losberg in South Africa. This is supplemented with 25 remote stations out to the largest baselines. The areas in which the remote stations are located can have their own climatic and geophysical conditions.

3 The Request for Information

Chapter 6 in the RfI concerns Physical Characteristics of the Site, and covers climate and geophysical or geotechnical data. The text in the RfI is reproduced here: “The physical characteristics of the site will have a strong influence on the design of the SKA and, second only to power costs, may dominate its maintenance and long-term operating costs. The sites will be evaluated on all physical characteristics of the site that influence the capital and operating costs, and the performance of the telescope. Information required 1) provide standard statistical information where appropriate on the following topics for the central core area (~50 km2) of the array: Environmental a) air temperature information for each month of the year:

mean

range (average of max-min over the days in the month)

average minimum and maximum over the days in the month

absolute minimum and maximum over the days of the month

typical and maximum rate of variation

b) humidity information for each month:

mean

range (average of max-min over the days in the month)

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average minimum and maximum over the days in the month

absolute minimum and maximum over the days of the month

c) rainfall information for each month:

mean per day

absolute maximum daily rainfall over the days of the month

absolute maximum quantity of rain that can fall in a 30 minute burst in that month

d) dew-point temperatures (derived information)

e) occurrence of ice formation, hail, and pooling of water

f) cloud cover

g) wind information for each month:

speed mean

speed average monthly

speed absolute maximum over the month

gust (<10s duration) absolute peak over the month

direction/speed histograms, over each month

h) solar radiation, daily solar exposure information per month:

mean

minimum

maximum

i) airborne particles (e.g. dust and sand)

j) airborne chemicals (e.g. salt)

k) animals, insects, birds from which protection is required or special measures taken

l) identify any restrictions due to indigenous use, ownership, or customs, or due to any legislated protection of flora or fauna

m) wildfires

n) seismic stability

Geotechnical a) identification of sub-surface strata to depths appropriate for SKA components (dishes, buildings,

bunkers, etc.), including corrosive minerals such as salt

b) water table

depth

water quality

flow rates

c) sub-surface conductivity profile

d) surface and subsurface (10 cm and 100 cm depth) temperatures:

monthly maximum

monthly minimum

diurnal variation (information on subsurface variation can be measured data or modelled, based on applicable soil heat transfer properties)

Severe Weather Events e) thunderstorms and associated lightning

f) strong winds (>50 km/hr), tornado/cyclone occurrence

g) narrow, localized storm events (storm cells)

h) large-size hail events

i) flooding, flash flood occurrence

j) dust storms

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2) It is expected that geotechnical properties vary over the extent of the array. Environment and extreme weather properties will differ as well, especially for the remote station locations. The site-specific configurations generated by the SPDO in conjunction with the individual candidate sites define the regions of interest. The responses should also describe whether there are spatial variations in the factors listed above for the following regions: a) Along the spiral arms of the array out to 20 km from the centre

b) Further along the spiral arms at positions of antenna clumps out to 180 km

c) Individual remote sites Data sources As a minimum, information is requested for the parameters mentioned above, as obtained or derived from the most precise source from the following list: 1. The 2005 site submissions. These contained considerable information on the environmental and severe weather events and can be reproduced in the response, if appropriate; 2. Weather stations. The two sites have operated weather stations at their sites for a number of years. Relevant data on (at least) temperature, humidity, wind speed and wind direction data, plus derived information such as dewpoint should be provided. The data should be made available in two forms: a) Raw data as recorded by the weather station. A time resolution of order 10 minutes is desirable to allow a meaningful assessment of the rate of variation of air temperature. b) Processed data in graphs; 3. National meteorology field station data: If weather stations operated by the national meteorological authority do not exist within the regions in the main zones of the telescope, information from the closest weather station(s) can be used. Outcome Report by the SPDO on the strengths and weaknesses of the Candidate Sites with respect to the physical characteristics of the sites.”

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4 Information supplied

The following sections contain extractions from the site responses to the Request for Information. Site summaries are first provided in alphabetical order (Australia/Australasia followed by South/Southern Africa), followed by a paragraph that comments on and compares the information supplied. Section 4.1 first provides an overview of the information received in response to the RfI.

4.1 Overview

A summary is presented on the information and documentation provided by the two respondents on the topic of Physical Characteristics. 4.1.1 Australasia

The response from the Australian-New Zealand Coordination Committee contains a chapter on Site Physical Characteristics, [3]. This chapter reports on these characteristics in 67 pages, supplemented by these Attachments contained in the same physical document:

Attachment 10: Mask Documentation for the Australian candidate SKA site

This is a document that describes the masks that were used during the site-specific array configuration designs. The mask is a GIS-derived layer that is placed on the map to define where placement of antenna receptors is allowed or not, for reasons ranging from EMI constraints to geophysical buffer zones. The specification for the masks is given in [5]. The masks were used to design the site-specific configurations within the 180km radius central area, and as such provides information within this area in the context of physical characteristics.

Attachment 11: Wind roses

Wind roses provide a graphical representation of statistics on direction, strength and frequency of wind conditions at a given location. The attachment provides annual and monthly statistics for the core region (wind roses for the Australian continent are shown in the main report). The report does not specify the period in which these statistics were obtained but does mention the number of observations used.

Attachment 12: New Zealand physical characteristics

Information provided here concerns New Zealand, and covers the following aspects: Population density, land use, environmental (air temperature, humidity, rainfall, cloud cover, wind, solar radiation, animals, wildfires, seismic activity and severe weather events).

Table 1: Overview of information supplied, Australasia

“All Years” This term is referred to throughout the Australian-New Zealand submission in relation to the data supplied by weather stations nearest to the SKA site as shown in Table 2: Australian weather stations: locations and reporting period. It is not clear how the data from these individual weather stations relate to the data provided in the submission.

Weather Station Distance from the Core Years

Murchison 70km West 1987-2011

Murgoo 70km South 1889-2011

Meekatharra Airport 180km East 1944-2011

Cue 145km South-East No years given

Errabiddy 145km North No years given

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Table 2: Australian weather stations: locations and reporting period.

4.1.2 Southern Africa

Chapter 5 of the South African response to the RfI deals with the Physical Site Characteristics, [4]. This chapter reports on these characteristics in 22 pages, with the bulk of the information contained in 38 Annexures:

F1.1 to F1.7: Chapter 5 of RSA 2005 Bid Submission (Climate at the SKA sites) and further annexes.

The RfI indicates that relevant information that was supplied during the shortlisting process in 2005 could be part of the physical characteristics information package. Copied from the 2005 bid package, F1.1 and F1.2 cover climate and weather at the core site. F1.3 through F1.6 cover geological and geotech constraints, geology, geotechnical and mineral deposits reports. F1.7 covers inundation mapping.

F2: Phase Stability in Fibre Optic Cables

Contains modelled and measured subsurface temperature profiles.

F3.1 to F3.3: HHK Soil resistivity survey for KAT7

Addresses sub-surface conductivity. These are reports of investigations by a contractor, carried out in-situ for KAT7.

F4.1 to F4.4: Geotechnical reports for MeerKAT and SKA

Detailed and summary reports on geotechnical investigations for dish foundations carried out by a contractor. F4.3 is the MeerKAT CDR report, that includes geotech information.

F5: MeerKAT Environmental Impact Assessment Report

This impact assessment is included to show that there are no ecological reasons to prohibit development of radio astronomical activities in the core area.

F6.1 to F6.7: Raw measurement data from SKA Weather Station and derived statistics on temperature, humidity, rainfall, dewpoint, wind and solar radiation

Spreadsheets that contain raw and derived data from the weather station at the core site.

F7: Aerosol Optical Thickness report

A contractor’s report on aerosol optical thickness as calculated from satellite data over the SKA locations in Southern Africa.

F8.1 to F8.4: Graphical representations on frost days, wildfires, annual solar radiation and soil pH

Maps supporting the information given in the main report.

F9.1 to 9.3: Physical Characteristics at SKA Remote Stations, and Annexures A and B

Very comprehensive report on all physical characteristics is presented in F9.1, which covers the remote stations but also addresses the conditions along the spiral arms. Detailed weather information at the remote sites is presented in F9.2, and water quality information in F9.3. This work was carried out by a contractor.

F10: Repository of Monthly Wind Roses

Wind roses provide a graphical representation of statistics on direction, strength and frequency of wind conditions at a given location. Monthly wind roses are included in individual documents, while the annual average wind rose is given in the main document. The statistical period is 6 years.

F11: SKA Site Weather Parameters from AQUA Satellite Data

A direct comparison between Southern African and Australasian core sites on several parameters is made, based on satellite data covering almost 8 years, as assembled and delivered by a contractor. Local night and daytime parameters reported on are: total atmospheric water vapour content, cloud coverage, surface air temperature and surface skin temperature. This document has not been used as a reference

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or source of information for the current report.

F12.1 to F12.5: Analysis of Geotechnical Conditions at the SKA Remote Stations

A contractor’s desk study report on geotechnical conditions is presented for the central and remote sites. The reports concentrate on dish locations. A main report (F12.5) and its 4 annexes are included.

Table 3: Overview of information supplied, Southern Africa

4.2 Environmental

In the following sections the responses to the environmental paragraph of the Request for Information is addressed. Per topic the information has been condensed as much as possible while attempting to preserve the richness of the information supplied. There was a significant difference in presentation between the two submissions in that Australia has presented data mainly in tabular format along with contour plots on the map with the configuration indicated, while South Africa delivered their information mainly in graphs. To allow comparison of the information the Australian data was also been converted to graphs by the SPDO. Per parameter three sections are presented in the following sections:

1. The Australian contour plots taken from the response document; 2. The South African summary graphs, likewise taken from the response document; 3. Comparison graphs, combining data that was presented either in tabular or graphical format

by the site proponents. Data sources Australia Environmental information was compiled from the Australian Bureau of Meteorology (BOM) weather stations. The information pertaining to the core location was derived from various stations in the area, ranging from 70 to 180 km from the centre in addition to data measured by the MRO’s own weather station. For the latter the data covers a limited period (the year 2010). The SPDO’s request for delivery of the raw data from that weather station was declined, with the argument that this data was not deemed to be representative because of its location on top of a local outcrop (‘breakaway’). The submitted report notes that the variance in results from the BOM weather stations within the 180 km radius zone is minimal. For various stations reporting periods are mentioned that go back to 1889 in one case, but no overview is given of what data, from which station and what time period has ended up in the data presented in the report. Data sources South Africa Measured data from the weather station at the Karoo site have been made available in raw format and have been used in the submitted documents and also as data source for the current report. This station has been in operation since 2005, with minor interruptions, and has delivered in-situ data on 6 basic weather parameters ever since. A second weather station at the location of KAT7 has been in use since early 2011. Weather information at the core location has been based on this weather station. Datasets from weather stations from government authorities (ARC-ISCW and SAWS) have been used to characterise conditions along spiral arms and the remote sites. Satellite datasets and modelled datasets were used to complement weather station data where these were insufficient or not available. The submitted documentation presents weather data separately for the inner region, along the spiral arms and the remote stations for the South African configuration.

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4.2.1 Temperature Australia

Figure 1: Average daily mean temperature (annual), overlaid with SKA array stations.

Southern Africa

Figure 2: Statistics for temperature data, collected in the period 01/01/2005 to 31/03/2011, indicating the following: mean, range (average of maximum - minimum daily temperature), average maximum and minimum over the days of the month, absolute maximum and minimum over the days of the month, and average and maximum rate of variation over one hour timescales.

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Comparison

Figure 3: Graph of Maximum and Minimum Daily Temperatures (SA data processed from original weather station data; Aus data plotted from tabulated summary in report)

Figure 4: Chart illustrating daily variation in temperature for the first day of each month in 2010 (SA data processed from original weather station data; Aus data plotted from tabulated summary in report)

4.2.2 Humidity

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Australia

Figure 5: Average daily relative humidity (annual), overlaid with SKA array stations.

Southern Africa

Figure 6: Statistics for humidity data, collected in the period 01/01/2005 to 31/03/2011, indicating the following: mean, range (average for maximum – minimum daily relative humidity), average maximum and minimum over the days of the month, and absolute maximum and minimum over the days of the month.

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Comparison

Figure 7: This graph shows the mean relative humidity at the two core sites at 9am and at 3pm. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied).

Figure 8: Range of mean humidity (%) is given for 9am and 3pm for the two core sites. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied).

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4.2.3 Rainfall

Australia

Figure 9: Average rainfall (annual), overlaid with SKA array stations.

Values of the absolute maximum quantity of rain that can fall in a 30 minute burst in that month have been omitted from the submission. The submission states: “These data are not currently captured by any source in the area. Rainfall bursts can occur (as can be inferred from the highest daily rainfall statistics) and are caused by the occurrence of a broken down cyclone system dissipating through the area (...) or by isolated thunderstorm activity. As indicated by the 2010 daily statistics (ref) and the historical mean annual rainfall statistics in Table 12, they are not common.” Southern Africa

Figure 10: Statistics for rainfall data, collected in the period 01/01/2005 to 31/03/2011, indicating the following mean per day, absolute maximum daily rainfall over the days of the month, and absolute maximum rainfall in a 30 minute burst in that month.

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Comparison

Figure 11: The mean number of rainy days for each of the core sites. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied).

Figure 12: Mean rainfall for both core sites. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied).

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Figure 13: The minimum average monthly rainfall. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied).

Figure 14: The 2010 rainfall for both core sites is plotted together with the SA average rainfall for October 2005 to March 2011. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the Absolute Maximum Daily Rainfall (Table 13 in the submission).

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Figure 15: The highest daily rainfall in a given month. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied).

Figure 16: The maximum total monthly rainfall. The SA plot has been calculated from the raw data files which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied).

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Figure 17: The daily rainfall in Australia in 2010 overlaid with the maximum rainfall on any one day in SA between 27

th September 2005 and 2

nd April 2011. The SA plot has been calculated from the raw data files

which span from October 2005 to March 2011 to match the data in the Australian report. The Australian data is taken from the Absolute Maximum Daily Rainfall (Table 13 in the submission).

4.2.4 Dewpoint Australia

Figure 18: The average dewpoint temperatures at the MRO; All Years (see section 4.1.1 in Information Supplied).

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Southern Africa

Figure 19: Statistics for derived dewpoint data, collected in the period 01/01/2005 to 31/03/2011, indicating the following: mean, range (average of maximum – minimum daily derived dewpoint), average maximum and minimum over the days of the month, and absolute maximum and minimum over the days of the month.

Comparison

Figure 20: The mean, range (average of maximum – minimum daily derived dewpoint), average maximum and minimum over the days of the month, and absolute maximum and minimum over the days of the month for both sites. The SA plot has been taken from Annexure F6.4 which summarises data files which span from October 2005 to March 2011. The Australian data is taken from the summary table in the report from “All Years” (see section 4.1.1 in Information Supplied).

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4.2.5 Ice, hail and pooling Australia “None of the proposed array station sites are in an alpine or sub-alpine region, so ice loading is not a design consideration for Australian-based SKA buildings and associated infrastructure. Hail events are rare, as indicated by the low rate of thunder days. The core site is on the high ground (watershed) between two river systems. The surrounding relatively flat terrain can allow temporary pooling of water after heavy rain, but any such pools are shallow (a few centimetres) and short-lived.” Southern Africa

Figure 21: Inundation layer from South African 1:250,000 topographic series. This layer indicates areas that are subject to saturation, and hence pooling of water.

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Figure 22: Number of frost days per year. This indicates around 33 frost days per year but this is typically early morning and does not persist throughout the day.

Hail occurrence is covered in the in “Severe Weather Events” section. 4.2.6 Cloud cover Australia

Figure 23: Average monthly cloud cover at the MRO; All Years (see section 4.1.1 in Information Supplied).

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Southern Africa

Figure 24: Clear skies analysis for Van Wyksvlei and Brandvlei (58km and 96km from SKA Core site respectively)

Comparison

Figure 25: Graph of Cloud Coverage The SA plot has been replicated from the South African 2005 SKA Bid Submission data (SA Annexures F1.1 and F1.2) which spans from 1995 to 2004 overlaid with cloud cover data given in Table 15 of the Australian report; All Years (see section 4.1.1 in Information Supplied).

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4.2.7 Wind

Figure 26: Graph showing an overview of the wind characteristics of both core sites (m/s). The SA plot has been plotted from the data file in Annexure F6.6 which spans from 01/01/2005 to 31/03/2011. The Australian data is plotted from the data in tables 16, 17, 18 and 19 in the report from “All Years” (see section 4.1.1 in Information Supplied).

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Sum

mar

y Australia

Wind rose key for all Australian charts

Southern Africa

Wind rose for all wind speed data (m/s),

collected 01/01/2005 to 31/03/2001

Jan

uar

y

Feb

ruar

y

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Mar

ch

Ap

ril

May

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Jun

e

July

Au

gust

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Sep

tem

ber

Oct

ob

er

No

vem

ber

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Dec

emb

er

Figure 27: Windroses for both core locations.

Both proponents have provided similar windrose statistics, where the length of the bar/segment indicates the percentage occurrence in a given direction. The Australian bar-segments encode the wind speed ranges in km/h, where the South African graphs use colours in m/s, see legend. Instead of modifying the provided graphs the following conversion table should help in comparing these plots.

Beaufort mph kts km/h m/s

1 1-3 1-3 1-5 0.3-1.4

2 4-7 4-6 6-11 1.7-3.1

3 8-12 7-10 12-19 3.3-5.3

4 13-18 11-16 20-28 5.6-7.8

5 19-24 17-21 29-38 8.1-10.1

6 25-31 22-27 39-49 10.8-13.6

7 32-38 28-33 50-61 13.9-16.9

8 39-46 34-40 62-74 17.2-20.6

9 47-54 41-47 75-88 20.8-24.4

10 55-63 48-55 89-102 24.7-28.3

11 64-72 56-63 103-117 28.6-32.5

12 73+ 64+ 118+ 32.8+ Table 4: Wind speed conversions

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4.2.8 Solar radiation Comparison

Figure 28: Solar radiation; daily average, maximum monthly average and minimum monthly average. The SA data has been plotted from the data files in Annexure F6.7 which span from 15/10/2004 to 05/07/2011. The Australian data is taken from table 20 in the report from “All Years” (see section 4.1.1 in Information Supplied).

It is noted here that there appear to be differences in the statistical methods that have been applied by the two proponents for the average minimum solar radiation. Where the graphs follow each other quite closely for the other average values, the minima show large differences.

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4.2.9 Airborne particles and chemicals Australia Dust: The submission document states that work at the MRO has demonstrated that the core site and 180 km region are not in a dusty environment. Dust storms are not typical. Chemicals: It is stated that there are approximately 20 salt lakes in Australia, seven in Western Australia. The two nearest salt lakes to the core are both 375 km away. The SKA is isolated from saltpan areas. Southern Africa The submission document uses Aerosol Optical Thickness (AOT) measurements by the GlobAEROSOL satellite. Daily AOT maps provide an indication of amount of chemical and particulate matter in the atmosphere. The main submission document contains a graph for the year 2007, which is reproduced here. The analysis is further explained and monthly maps provided in an Annexure F7 provided by an external contractor. The AOT over all areas of relevance to the SKA, including the remote sites falls below the global average for all months of the year, which leads to their conclusion that the impact of aerosols is likely to be negligible. The submission document does not mention the presence of saltpans or the occurrence of dust storms.

Figure 29: Aerosol Optical Thickness (AOT), as measured in summer and winter at the SKA core and skirt region in 2007. The global mean is provided for comparative purposes.

4.2.10 Animals, insects and birds Australia The submission document mentions that there is no risk of “land predators to humans”, but does list venomous snakes and spiders, noting that the risk is very low in Western Australia. It is proposed that at remote stations maintenance crews work in pairs. Southern Africa The submission document notes that the predominant wildlife that needs to be considered near the core is the ‘sociable weaver’, a bird that builds large communal nests on structures. Experience has shown that simple means can be used to mitigate the risk. No other threats are listed.

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4.2.11 Restrictions in use The RfI requests proponents to identify any restrictions due to indigenous use, ownership, or customs, or due to any legislated protection of flora or fauna. Australia The submitted document notes that Commonwealth and State environmental, heritage, land access and native title approvals will be required for placement of infrastructure. These procedures have been followed for currently existing facilities at the MRO and the fibre cable route to Geraldton and have not hindered the deployment. The document mentions that there is evidence that for large scale mining operations “such matters can be satisfactorily managed”. Southern Africa The South African submission states that the land upon which the core and skirt (to 13km from centre) regions are to be located is not subject to any land restrictions. Currently two farms at the centre are owned by the National Research Foundation (NRF). The Astronomy Geographic Advantage (AGA) Act would provide a basis for further land acquisition. The MeerKAT Environmental Impact Assessment (EIA) Report that has been provided as Annexure F5, which covers a large part of the inner area, concludes that there are no significant ecological reasons preventing development of a radio astronomy facility at the site. 4.2.12 Wildfires Australia The supplied document states that wildfires are rare in the area considered for the core and remote stations of the Australian configuration. Firebreaks are being maintained and monitored. Southern Africa The supplied document reports that datasets on active fire and burnt areas, as produced by the MODIS satellite system, have been inspected for wildfire events in the available timeframe from 1-01-2001 to 31-12-2010. No such events were recorded.

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4.2.13 Seismic stability Australia

Figure 30: Earthquake epicentre locations, overlaid with SKA array stations.

The map shows historic seismic activity and the submitted document appears to specify that these are events since 1820, stating that “the degree of seismic activity at the core and across all remote stations is low, with only one earthquake of significance recorded near the core”. Southern Africa

Figure 31: Seismic events, as recorded between 1973 and 2003 at the National Earthquake Information Centre, operated by the US Geological Survey.

The submission document notes that the single event in the plot may be unconfirmed because “almost all seismic activity in South Africa is as a result of deep level mining, and no active deep mines are located within several hundred kilometres of the SKA Core and Skirt region.”

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4.3 Severe weather

4.3.1 Thunderstorms and lightning Australia Information has been provided on ground flash density and number of annual thunder-days.

Figure 32: This map shows the number of annual thunder-days. Most remote stations “are subject to less than 20 thunder days per year”, with the exception of some stations in Northern and Eastern areas.

Figure 33: This map shows the annual lightning ground flash density. For most states a density of 1 per square kilometre per year is reported, for Eastern states 2 to 3 km

-2yr

-1. Northern areas have significantly

higher density, but no remote station

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Southern Africa The submission document refers to information on long-term severe weather events contained in the Bid Submission documents of 2005, which were included as Annexures. For two weather stations near the core the report gives the number of thunder-days over the period 1995 to 2005 as 30 and 37.

Figure 34: Annual lightning strike frequencies per square kilometre, averaged over the period 1975 to 1986. The contours are for lightning flashes per km

2. Note that on this map the remote stations are for the 2005

submission, which does not quite correspond to the current planned locations.

Figure 35: Annual lightning strike frequencies per km2 for the year 2002 in Southern Africa.

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4.3.2 Strong winds, cyclones, tornados Strong winds were defined as wind with speed >50km/hr and tornado/hurricane occurrence in the Request for Information. Australia The submission document states that “Cyclone activity in Australia is restricted to the tropical and sub-tropical coastal regions of the continent, usually between the months of November and April. These cyclone areas can be inferred from Figure 32 [current document reference], with reference to the thunder associated with cyclone and storm systems with 60-80+ thunder days”. This figure and Figure 38 (classification of wind regions on the Australian continent) “show that there are no stations in cyclone susceptible areas.” It is further noted that “Dissipating tropical cyclones can cause strong winds through the Western Australian inland: in March 1999, the dissipating cyclone Vance, which crossed the coastline 600km north of Boolardy, tracked close to Boolardy and winds near Boolardy reached 106 km/h (...) The highest wind speed recorded in the region was 148 km/h at Meekatharra in January 1968. However, most dissipating cyclones occur further north than the proposed sites for array-stations”. To give an idea of the historical data on tropical cyclones we have included a map (Figure 36: Australian Government BOM public information on tropical cyclone traces, over a 100 year period. Figure retrieved from BOM website; not from submitted document.) in which traces of tropical cyclones are plotted as provided by the Australian Government BOM in the form of a publicly accessible web site.

Figure 36: Australian Government BOM public information on tropical cyclone traces, over a 100 year period. Figure retrieved from BOM website; not from submitted document.

This can be put into context using the worldwide map of tropical cyclone traces given in Figure 37: Worldwide tropical cyclones over the years 1945 to 2006. Note that all tracks across the Australian continent are classified as tropical storms or depressions, in line with the assessment that these are dissipating cyclones. [Source: http://en.wikipedia.org/wiki/File:Tropical_cyclones_1945_2006_wikicolor.png retrieved 10/11/2011].

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Figure 37: Worldwide tropical cyclones over the years 1945 to 2006. Note that all tracks across the Australian continent are classified as tropical storms or depressions, in line with the assessment that these are dissipating cyclones. [Source: http://en.wikipedia.org/wiki/File:Tropical_cyclones_1945_2006_wikicolor.png retrieved 10/11/2011].

Figure 38: Classification of the Australian continent in wind regions.

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Figure 39: Average number of strong winds at the MRO, based on BOM data over an unspecified number of years. The submission document states that “similar averages are experienced over the entire 180 km region.”

Southern Africa The submission document states that “the broader definition of storms includes minor occurrences such as ‘dust devils’. These do not pose any risk of damage (…)”. The report notes that for two weather stations near the core no occurrences of wind or dust storms, cyclones/hurricanes have been recorded in the period 1961 to 2004. There is some concern about the occurrence of strong winds and tropical cyclones for remote stations on Madagascar. This is addressed in Annexure F9.1, where an overview of cyclone traces is given. To give an idea of the historical data on tropical cyclones in the western Indian Ocean area we have included a map (Figure 40) in which traces of tropical cyclones are plotted.

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Figure 40: Detailed view of tropical cyclones traces (1980-2005). This graph from publicly available sources; not extracted from submission document. [Source: http://upload.wikimedia.org/wikipedia/commons/2/23/Global_tropical_cyclone_tracks-edit2.jpg retrieved 10/11/2011].

4.3.3 Storm cells Storm cells are narrow and localised events of strong winds, usually associated with thunderstorms. Australia The submitted document states that “the areas being considered (…) are generally not in thunderstorm-susceptible regions (…)” and refers to the figure reproduced in this summary report as Figure 32. Southern Africa Storm cells have not been specifically addressed in the submitted main document, but are mentioned in Annexure F9.1. However they are interpreted there as general, non-localised storms. Maps are presented of storm tracks for the year 1998. As such the information has found its way into the wind statistics of section 4.2.7. 4.3.4 Large hail events Australia The submitted document states that “over the last 20 years in Western Australia there have been two large hailstone events, but neither have been in regions where it is proposed to site SKA array-stations”.

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Southern Africa The submission document has hail information listed in the severe weather section. It states that “although no size definition is provided for hailstones, first hand observer accounts indicate that hailstones very rarely exceed 5 mm in diameter. ” 4.3.5 Flooding, flash flood occurrence Configurations have been designed by the SPDO in cooperation with the two sites, using restrictions imposed on the placement of receptors by various factors, including flooding, pooling and inundation areas through the “mask”. Australia The submitted document states that “The areas being considered to host SKA array stations are not in flood-susceptible regions.” Attachment 10 reports on the Australian mask documentation. Southern Africa The considerations for designing the configuration according to the mask hold for South Africa as well. Nevertheless the question in the RfI was answered extensively: “First hand observer accounts indicate that heavy rainfall on the site may result in some water run-off and subsequent erosion. However, this has been mitigated through maintenance measures, such as the grading of roads where usage is high, the layering of additional material where erosion does occur, and the construction of appropriate water drainage channels at culverts. Approximately 25 mm of rainfall in half an hour is required to observe partial water runoff, such as next to roads that do not have appropriate culverts and drainage systems. Approximately 45 mm of rainfall in half an hour would be required in order to observe heavy runoff. The rainfall statistics provided in this report indicate that this occurs rarely.” Information on inundation mapping for the entire South African configuration is provided in Annexure F1.7. 4.3.6 Dust storms Australia Dust storms are not typical phenomena in the central area, see section 0 Southern Africa Dust storms are not typical phenomena in the central area, see section 0.

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4.4 Geotechnical

4.4.1 Sub-surface strata Australia

Figure 41: Typical ground profile at the core.

Surface Strata Lithology (Type) Percentage distribution of surface geology

intersecting the inner core (%)

Quaternary unconsolidated Map Sheet SG 50-10 codes: Ql, Qls, Qld, Qa, Qw, Qc and Qs. Alluvium, Colluvium, and Eolian clay, silt, sand, gravel and cobble. Gypsiferous and calcareous.

75.5

Quaternary consolidated Map Sheet Sg 50-10 codes: Csk, Czc Czs, Czl, Czz and Czu. Alluvium, Colluvium, and Eolian clay, silt, sand, gravel and cobble. Gypsiferous and calcareous.

7.0

Archean bedrock Map Sheet SG 50-10 codes: Agtc, Agwg and Anme. Tching Granite, Weiragoo Granite and Meeberrie Gneiss.

17.5

Table 5: Surface strata lithology for Australian core site

No further comment relating to sub-surface strata is provided in the submission.

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Southern Africa

Figure 42: Geological survey map, indicating lithographic classes of rock structure.

The submitted document includes the following information: “The following horizons1 were identified in the geotechnical investigation:

Hillwash o Transported hillwash horizon - slightly moist, silty sand, occasionally containing plant

roots, fine gravel or traces of calcareous concretions. Occurs over most of the site at a layer depth of 1 m;

o Aeolian hillwash horizon - silty sand with traces of fine mudstone gravel. Forms shallow dunes in many parts of the site. Thickness varies between 1 m to 2 m, with an average thickness of 1.2 m;

Alluvial streambed deposits o Loose alluvium - loose to medium dense silty sand, with occasional thin bands and

lenses (100 mm) of minor to abundant medium sub-rounded platy mudstone and sandstone gravel. Encountered in 12 of the boreholes investigated, and typically extends from ground level to 2 m depth;

o Cemented or Calcareous alluvium - fine and medium sub-rounded platy mudstone and sandstone gravel, with minor to abundant brown and white calcrete. Encountered in 32 of the boreholes investigated at an average thickness of 3.4 m, but varying from a minimum of 1 m to a maximum of 9 m;

Calcrete - A calcrete horizon was found in 10 of the borehole investations, as a transitional layer between alluvial and mudrock horizons. Layer thickness varies between a 1 m and 7 m;

Residual soils - Only present at two of the borehole investigations. Encountered from 5 m deep with an average thickness of 3 m;

Mudrock/Shale - Slightly weathered mudstone horizon encountered at 39 of the borehole investigations, from a minimum depth of 0.5 m to 10 m (the maximum depth of the borehole drill sites).”

1 A soil horizon is a specific layer in the land area that is parallel to the soil surface and possesses physical characteristics

which differ from the layers above and beneath.

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Following laboratory tests, and onsite field measurements, geotechnical parameters have been assigned to the various horizons taken from Annexure F4.1.

Horizon Description Comment

High Stiffness E [Mpa]

Strain G [Mpa]

Small Stiffness E0 [Mpa]

Strain G0 [Mpa]

Upper sandy horizon. Aeolian, hillwash and alluvium.

Proved to be incompetent as a founding horizon N/A N/A N/A N/A

Low strength gravel/calcrete horizon

Significant reduction in strength when saturated. Not considered as good founding horizon for this reason 70 25 150 60

Gravel and calcrete with interlayered sand.

Some reduction in strength with saturation. 140 55 450 175

Thick, high strength, solid calcrete 250 100 475 190

Mudstone

CSW testing in all cases indicates this is a conservative set of design values. 250 100 450 175

Table 6: Surface strata lithology for South African core and skirt regions

Figure 43: Subsurface pH map for the Core site, which can be used as a proxy for corrosive minerals. An average pH value of 8.4 is recorded across the Core and Skirt region.

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4.4.2 Water table Australia The submission document states that “Boolardy station lies in the Upper Murchison River Catchment and receives an average of 215mm of rain annually. Groundwater is readily available throughout the region. The Boolardy Station Homestead, 30km from the MRO obtains its domestic water and irrigation water from local sources and evidence from Boolardy and surrounding pastoral stations is that throughout the region there is ready access to groundwater with quite low salinity and good water quality. All drinking water, and water for ASKAP construction purposes has been obtained locally”. Southern Africa The submission document states that “A series of borehole investigations have taken place on the MeerKAT and SKA Core sites. (…) Based on the sustainable yields indicated, there will not be a shortfall of water for MeerKAT construction purposes. Further analysis on the full water requirements for the SKA will be necessary in order to determine adequacy.” A table is provided on borehole investigation results, including depth and sustainable yield. Annexure F4.4, a spreadsheet table on water quality has been included. “Chemical tests indicate that water treatment would be required for human drinking usage”. 4.4.3 Subsurface conductivity profile Australia The submitted document states that “An EM survey has been conducted on the MRO. The results agree with one might expect to find in this semi-arid environment. The near surface geology is likely to contain finer clay-like sediments, which will subsequently have higher moisture content and/or salt content, resulting in higher conductivity. As the sediment becomes more consolidated/cemented and/or coarser with depth, there is less pore space to contain water, hence the conductivity decreases. Likewise for igneous material such as the bedrock at the core, there is little to no pore space for moisture retention (only in weathered material), therefore the conductivity is poor. There are no saltpans in the vicinity. The earthing system for ASKAP has been designed to meet all applicable electrical safety and lightning protection standards and codes. The system employed uses a combination of earth grids adjacent to and under the antenna foundations, and multiple earth conductor rods placed in shallow vertical bores adjacent to the antennas and buildings. This solution takes advantage of the higher near-surface conductivity typical of the local geology”. No conductivity measurements have been provided. Southern Africa The submitted document states that “Subsurface conductivity of the Core site has been investigated through a series of commissioned surveys for the KAT-7 telescope. Detailed results of soil resistivity measurements (resistivity = 1/conductivity) at various depths are provided in Annexures F3.1, F3.2 and F3.3.” A summary table with measured conductivity values for sample KAT-7 telescopes has been provided in the submission.

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4.4.4 Surface and subsurface temperatures Besides surface temperatures, the Request for Information specified depths of 10 cm and 100 cm for the monthly maxima and minima, as well as diurnal variation (modelled or measured). Australia The submission document states that “Terrestrial minimum surface temperature is nominally measured at 9am and is taken to be the lowest temperature recorded since 6pm the previous day.” This would imply that these surface temperatures were measured at the MRO site. For the data provided for subsurface temperatures it is unclear whether these were measured or modelled.

Figure 44: Monthly surface and subsurface temperatures for the MRO. No monthly maxima have been provided for surface temperatures.

Southern Africa The submitted document mentions that “surface and sub-surface thermal profiles have been measured and modelled in detail…”. Annexure F2 deals with these profiles in the context of phase stability in fibre cables. No data has been provided for the monthly statistics. For the diurnal temperature variation at depth modelled results are provided, and duplicated here.

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Figure 45: “Theoretical and measured scaling of diurnal temperature variation, as function of soil depth. The resolution of the measurement sensors exceeds the temperature variation below depths of 0.5m. Measurement data below 0.5 m in depth is therefore not used to determine the fitted model.”

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5 Information supplied for stations outside the core

5.1 Overview

In the Request for Information it was specified to include information on all categories indicating differences in spatial distribution within the site-specific configuration: “The responses should also describe whether there are spatial variations in the factors listed above for the following regions: a) Along the spiral arms of the array out to 20 km from the centre

b) Further along the spiral arms at positions of antenna clumps out to 180 km

c) Individual remote sites” These sections discuss and summarise this information. It must be noted that the nominal site-specific configuration contain 25 remote stations each, which are drawn into the maps throughout the proponent’s submission documents, as well as in the current document. Not included in these are remote stations in New Zealand and Tasmania for the Australasian submission, and remote stations in Ghana, Kenya and Mauritius for the Southern African submission. These stations may become part of a future extended SKA configuration. This summary report does not include physical characteristics data for any of these remote site locations. 5.1.1 Australia The Australian submission includes a series of geographical plots of various physical characteristics overlaid with the SKA array station configuration. These plots are prepared by the Australian Government Bureau of Meteorology and provide an overview of the differences between the core site and remote stations. Attachment 12 has also been provided which gives equivalent plots and information for New Zealand. 5.1.2 South Africa Annexure F9.1 (“Physical Characteristics of SKA Remote Sites”) is a comprehensive 110 page report on the physical characteristics at locations on the 5 spiral arms and remote stations. The level of detail differs for the South African remote stations (very detailed) and the stations located in the other African countries. Annexure F9.2 is an appendix to the former (subtitled “Weather conditions report for SKA South Africa”) and provides very detailed information on all weather related parameters for all 25 Southern African remote station locations, in 105 pages.

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5.2 Environmental

5.2.1 Temperature Australia A map with daily mean temperature (annual) contours, with the Australian remote stations indicated, was provided in the submitted document, and reproduced in Figure 1. South Africa

Figure 46: Spiral Arms with associated weather stations *The following figures use the term “All Weather Stations” meaning all the weather stations mapped on this diagram+

Figure 47: Temperature summary throughout all weather stations.

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For the remote stations Annexure F9.2 has provided air temperature information (mean, average maximum, average minimum, absolute maximum and absolute minimum temperatures), which we have summarised in the table below.

Station ID

Absolute maximum temperature (°C)

Month of maximum temperature (°C)

Absolute minimum temperature (°C)

Month of minimum temperature (°C)

Nam 0 39 December 2 June

Nam 1 41 December 6 September

Nam 2 42 October 3 June

Nam 3 40 October 12 June

Zam 0 38 October 10 June/August

Bot 0 40 November 2 July

Bot 1 43 October 1 June

Bot 2 41 October 8 June

Moz 0 42 October 12 June

Moz 1 33 October 8 June

Mad 0 36 October 7 August

Mad 1 30 October 9 August Table 7: African remote station temperature information, for the year 2010.

5.2.2 Humidity Australia A map with average daily relative humidity (annual) contours, with the Australian remote stations indicated, was provided in the submitted document, and reproduced in Figure 5. South Africa

Figure 48: The relative humidity throughout all weather stations

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Station ID

Absolute maximum relative humidity (%)

Month of maximum relative humidity (%)

Absolute minimum relative humidity (%)

Month of minimum relative humidity (%)

Nam 0 96 May 4.5 October

Nam 1 92.5 July 3 October

Nam 2 100 April/November 5.5 September

Nam 3 98 March 6 Aug/Sept/Oct

Zam 0 100 Nov - April 8 August

Bot 0 91 January 6 September

Bot 1 100 April 6 October

Bot 2 100 January/February 7 August/October

Moz 0 100 November 16 September

Moz 1 100 year round 15 October

Mad 0 100 August 11 September

Mad 1 100 January/March 31 November Table 8: African remote station relative humidity information, for the year 2010.

5.2.3 Rainfall Australia A map with average rainfall (annual) contours, with the Australian remote stations indicated, was provided in the submitted document, and reproduced in Figure 9. South Africa

Figure 49: Rainfall summary throughout all weather stations

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5.2.4 Dewpoint Australia No dewpoint data was provided for the remote station locations. South Africa

Figure 50: Summary of dewpoint throughout all of the weather stations

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5.2.5 Ice, hail and pooling Australia “None of the proposed array station sites are in an alpine or sub-alpine region, so snow and ice loading is not a design consideration for Australian-based SKA buildings and associated infrastructure.”” South Africa

Figure 51: Annual number of frost days

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Figure 52: Hail frequency map of South Africa

Figure 53: Pooling of water for the central region

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5.2.6 Cloud cover Australia No cloud cover information was provided for the remote station locations. South Africa

Figure 54: Annual bright sunshine hours for the core, spiral arms and remote stations

5.2.7 Wind Australia

Figure 55: Wind speed during summer months, overlaid with SKA array-stations.

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Figure 56: Wind speed during winter months, overlaid with SKA array-stations.

A classification of the Australian wind regions was included in the submitted document, and reproduced in Figure 38. South Africa

In Annexure F9.1 detailed information on wind speed and direction has been provided for all 25 remote stations. Statistics included are monthly average wind speed, average maximum wind speed and absolute maximum wind speed, and wind direction histograms. As an example of the data presented we have randomly selected a remote station (REM-10) and include it in this summary report.

Figure 57: REM-10 Wind Speed Data

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Figure 58: REM-10 Wind Direction Data

5.2.8 Solar Radiation Australia

Figure 59: Average daily solar exposure (annual), overlaid with SKA array-stations.

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South Africa

Figure 60: Solar radiation summary for all weather stations

5.2.9 Airborne particles and chemicals Australia No information on airborne particles and chemical was provided for the remote station locations. South Africa

Figure 61: 2007 AOT at 550nm for SKA sites

5.2.10 Animals, insects and birds Australia The general statement in the submitted document is: “Australia and New Zealand contain no land predators to humans that present any kind of risk. (…) Standard occupational, health and safety (OH&S) measures will be put in place for on site personnel, including procedures to minimise risk

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from workers inadvertently placing exposed limbs in any danger of being bitten by venomous snakes or spiders.” South Africa

Figure 62: Map of South Africa overlaid with South African National Parks (SANPARKS) and SKA array configuration

5.2.11 Restrictions in use Australia No specific information on restrictions in use for remote station locations was included in the submitted document. South Africa

Figure 63: Restrictions due to indigenous use - Northern Cape

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5.2.12 Wildfires Australia “Destructive bushfires have occurred in Australia’s southeast and southwest, where there are eucalypt and acacia forests. The very sparse scrub-like vegetation in the desert and marginal farming regions of inland Western Australia, the Northern Territory and South Australia where array-stations are located makes bushfires a rarity in these regions. Historically, any fires in the central area have been small grass fires, which occurred in years where there was above average rainfall. Property owners maintain a three to four metre firebreak along perimeter fences and keep dedicated emergency water supplies. Maintenance of firebreaks is monitored by local shire councils.” South Africa

Figure 64: Remote stations with active fires 2010

Key Remote Stations with Active Fires SKA Remote Dishes

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Figure 65: Active fires 2010 - Core and spiral arms

5.2.13 Seismic stability Australia A map with earthquake epicentre locations, with the Australian remote stations indicated, was provided in the submitted document, and reproduced in Figure 30. South Africa

Figure 66: Seismic activity

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5.3 Severe weather

5.3.1 Thunderstorms and lightning Australia Maps with annual thunder-days and annual lightning ground flash density, with the Australian remote stations indicated, were provided in the submitted document, and reproduced in Figure 32 and Figure 33. Please see section 4.3.1. South Africa The information in section 4.3.1 covers some of the remote station locations as well. An additional map of lightning ground flash density that indicates the locations of the South African and some African remote stations is included here, taken from Annexure F9.1. No information was found on thunderstorms and lightning at the more distant remote stations.

Figure 67: Lightning and ground flash density at South African and nearby African remote stations.

5.3.2 Strong winds Australia The information provided in the submitted document and publicly available information on the occurrence of tropical cyclones over mainland Australia was already discussed in section 4.3.2. South Africa The information provided in the submitted document and publicly available information on the occurrence of tropical cyclones, in particular near the eastern part of the Southern African configuration, was already discussed in section 4.3.2. Here an additional figure on tropical storm tracks overhead Madagascar is included, taken from Annexure F9.1.

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Figure 68: Tropical storm tracks over Madagascar, 1999-2011

5.3.3 Storm cells The information on storm cells, including for the remote site locations was already presented in 4.3.3. 5.3.4 Large hail events See sections 4.3.4 and 0. 5.3.5 Flooding, flash flood occurrence Australia See information provided in section 4.3.5., where reference has been made to the use of the mask to avoid areas of flooding it should be noted that no information has been provided outside the central 180 km region (the region covered by the mask is 180 km in diameter.) South Africa See information provided in section 4.3.5. In addition flooding risk for all remote stations is indicated on the figure taken from Annexure F9.1 below.

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Figure 69: Flooding The Annexure has also included a map of mean annual run-off, which is reproduced here. “Run-off plays an important role in flash flood occurrence. Where run-off is high, it has the ability to aid flash floods. (…) REM 13 and REM 15 fall into the run-off range of 21.8-62.2mm of run-off during the year. This is due to those sites having a high rainfall as well as their location.”

Figure 70: Mean annual run-off of South Africa

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5.3.6 Dust storms Australia Dust storms are not typical phenomena in the central area, see section 0. No information has been provided on the other areas covered by the Australian configuration. Southern Africa Dust storms are not typical phenomena in the central area, see section 0. No information has been provided on the other areas covered by the Southern African configuration.

5.4 Geotechnical

5.4.1 Sub-surface strata Australia South Africa

Figure 71: Subsoil pH levels of South Africa

5.4.2 Water table Australia South Africa Annexure F9.1 states: ‘The guidelines used for the water quality was established by the Department of Water Affairs South Africa. The water quality has been divided into 4 categories, depending of usage of the water. For SKA purposes, category 3 was used as the base. “Category 3: Processes for which domestic water quality is the baseline minimum standard. Water of this quality may be used in the process without further treatment, or minimum treatment using low to standard technology may be necessary to reach the specifications laid down for a desired water quality. Costs of further in-house treatment are not significant in the economy of the process” Green, indicates acceptable.

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Orange, indicates minor to moderate concern. Red, indicates moderate to major concern.’

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Figure 72: Bore hole water quality and flow rate

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5.4.3 Subsurface conductivity profile Australia South Africa

Figure 73: Surface Conductivity map for the SKA site

5.4.4 Surface and subsurface temperatures Australia No information on surface and sub-surface temperatures beyond the core region were included in the submitted document. South Africa The submitted document states: “As soil conditions do not vary significantly across the SKA spiral arms, it is likely that surface and sub-surface thermal profiles will be consistent with measurement data in the SKA Core and Skirt region.”

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6 References

[1] A Preparatory Phase proposal for the Square Kilometre Array, PrepSKA, EC FP7, 2007 [2] Request for Information from the candidate SKA sites, rev. F, SSG-RfI-001, 22-3-2011 [3] Request for Information from the candidate SKA sites, Site Physical Characteristics, ANZSKA, 15-

9-2011 [4] South African Response to the SSG Request for Information, Chapter 5, 15-9-2011 [5] SKA Mask Specifications, v1.0, R.P. Millenaar, M. Storey, C. Wilson, A. Tiplady, 20-4-2010