Report from DAOS-WG

Roger Saunders and Ron Gelaro with input from WG members

Overview

• WG Matters (meeting, membership, ..)

• Highlights from Exeter meeting

• Paper on targeted observations

Mission statementTo achieve its mission the DAOS WG, in collaboration with

the CBS OPAG-IOS:

• Addresses Data Assimilation issues including the development of improved understanding of the sources and growth of errors in analyses and forecasts

• Promotes research activities that lead to a better use of observations and the understanding of their value

• Provides input and guidance for THORPEX regional campaigns for the deployment of observations to achieve scientific objectives.

Current proposed membershipRon Gelaro(D), Co-chair

NASA, USA

Roger Saunders(O), Co-chair

Met Office, UK

Stefan Klink(O)

DWD, Germany

Carla Cardinali(D)ECMWF

Chris Velden(O)Univ Wisconsin-CIMSS,

USA

Tom Hamill(D)NOAA, USA

Tom Keenan(O)CAWCR, Australia

Rolf Langland(D)NRL, USA

Bertrand Calpini (O) MeteoSwiss, Switzerland

Andrew Lorenc(D)MetOffice, UK

Florence Rabier(D/O)Météo-France

Prof. Bin Wang(D), Chinese Academy of Sciences, China

Michael Tsyroulnikov(D)HydroMet Centre, Russia

Mark Buehner (D)Environment Canada

Sharan Majumdar (D) RSMAS, Univ Miami,

USA

Needs approval by ICSC-9 O=Observations D=Data Assimilation

3rd THORPEX DAOS Working Group meeting

Université du Québec à Montréal8-9 July 2010

Montréal (Québec) CANADA*http://web.sca.uqam.ca/~wgne/DAOS/DAOS3_meeting/

DAOS-4 WG meeting Exeter 27-28 June 2011

• Review targetting paper

• Updates on THORPEX campaigns

• Review observing systems

• Review developments in data assimilation

• WG matters

The intercomparison experiment on the impact of observations

A goal of THORPEX is to improve our understanding of the ‘value’ of observations provided by the current global network

In 2007, DAOS-WG proposed a comparison of observation impacts in several forecast systems, facilitated by the emergence of new (adjoint-based) techniques

Experiments for a baseline observation set were designed by DAOS members from NRL, GMAO, EC, ECMWF, Météo-France …so far, results obtained for 4 systems: NRL, EC, GMAO, UKMO

• optimize the use of current observations• inform the design/deployment of new obs systems

AMSU-A, Raob, Satwind and Aircraft have largest impact in all systems

GMAO GEOS-5NRL NOGAPS

EC GDPS

8

Global domain: 00+06 UTC assimilations Jan 2007

Daily average observation impacts

METOP : MetOp ATOVS,MetOp IASI, MetOp ASCAT NOAA : NOAA15 ATOVS AMSUA, NOAA17 ATOVS HIRS, NOAA18 ATOVS, NOAA19 ATOVSOTHER LEO: EOS AIRS, F16 SSMIS, ERS, WINDSATGEO : GOES, MTSAT, MSGAircraft : AMDAR, AIREPSONDE : PILOT, TEMPSFC Land : SYNOP, BOGUSSFC Sea : BUOY,SHIP

Total Impact = Number of soundings/profiles * mean observation Impact of each sounding/profile

Observation Impacts to NWP forecast

-16-12-8-40

Ob

serv

atio

n T

ypes

Total Observation Impact[J/kg]

METOP

NOAA

OTHER LEO

GEO

AIRCRAFT

SONDE

SFC LAND

SFC SEA

Impact of different observation platforms

Relative Contribution of Observations to NWP forecast

3.1

15.3

13.2

9.9

5.9

7.9

20.4

24.3

0 5 10 15 20 25 30

Ob

serv

atio

n T

ypes

Relative Observation Impact[%]

METOP

NOAA

OTHER LEO

GEO

AIRCRAFT

SONDE

SFC LAND

SFC SEA

10

The Concordiasi Project

Additional observations over Antarctica for NWP

F. Rabier, V. Guidard, S. Noton-Haurot, A. Doerenbecher, D. Puech, P. Brunel, A. Vincensini, H. Bénichou, Météo-FrancePh Cocquerez, CNESA. Hertzog, F. Danis, IPSL/LMDT. Hock, S. Cohn, J. Wang NCARC. Sahin, A. Garcia-Mendez, J-N Thépaut ECMWFA. Cress, U. Pfluger, DWD R. Langland, NRLG. Verner, P. Koclas, CMCR. Gelaro, NASA/GMAOC. Parrett, R. Saunders Met OfficeY. Sato JMA

11

CONCORDIASIFlights overview Sept 2010-January 2011

2010, a stable Austral Winter Polar Vortex

12

Sea-Ice limit

640 Dropsondes (20100923-20101201)

13

Sensitivity to obs performed by NRL

Rolf Langland, NRL

DROPSHIP/BUOYRAOB

DROP

GEOS-5 Observation Impacts for Concordiasi Time Series of All Drop Cases − 60°S-90°S Observations

Improved cases: RAOB-79%, SHIP/BUOY-72%, DROP-67%

ParticipantsCMCDWDECMWFGMAOMétéo-FranceMet OfficeJMA

Data Assimilation Monitoring Statistics over the Antarctic

RMS(O-F) Raob T Obs Count Raob T

Radiosonde Background Temperature Departures (O-F)

Courtesy F. Rabier, Météo-France

All models have difficulty predicting lowest-level temperatures

16

Concluding remarks on ConcordIASI

Concordiasi provided an unprecedented data coverage of meteorological observations over Antarctica

Both dropsonde and gondola information seem to have a positive impact on forecast performance (preliminary results from NRL, DWD and MF)

Gondola temperature data at 60hPa shows the largest model errors in areas of strong gravity-wave activity

Dropsonde information confirms statistics obtained with radiosondes and provide a more global view

Most models have problems predicting the lowest level temperatures

DIAMETDIAbatic influences on MEsoscale structures in

extratropical sTorms

Geraint Vaughan, Manchester PI

John Methven, Reading PI

Doug Parker, Leeds PI

Ian Renfrew, East Anglia PI

DIAMET flying programme

• Autumn 2011– 14-30 September, flying from Cranfield– detachment to Exeter 24 Nov – 14 Dec– 8 IOPs planned, 4 double and 4 single

flights

• July-August 2012– Cranfield-based– Focus on high-impact rainfall– 2 double, 3 single flights

T-NAWDEX plans

• Andreas Dörnbrack, Heini Wernli, Andreas Schaefler and Ulrich Corsmeier

• Bidding for DLR Falcon time in August/September 2012:– August link with DIAMET conducting quasi-Lagrangian experiment

to examine diabatic air mass modification– September link with HYMEX on water vapour fluxes into the Med

region.– Only wind LIDAR will be available (not water vapour LIDAR)

• T-NAWDEX international experiment as originally envisaged: aiming for 2014/2015 including aircraft from Germany, UK, France and USA (HIAPER)

Ground-based GPS on GTSObservations available from E-GVAP

http://egvap.dmi.dk

• ASCAT winds for Irene and model background

• Only one scat now used for NWP

• Trials using scatterometer on Oceansat-2

Importance of Scatterometer winds

ISRO L2B vs ECMWF• SDs of

differences given

• Outliers reason for degradation w.r.t. OWDP ?

Bias at low speeds

Vector RMS difference of 2.6 m/s (>2 m/s)

1.56 m/s

1.87 m/s 1.76 m/s

14.29 deg

v2010

Weather Radar Global Extent

ASSESS THE CURRENT AND POTENTIAL CAPABILITIES OF WEATHER RADARS FOR THE USE IN WMO INTEGRATED GLOBAL OBSERVERING SYSTEM (WIGOS )by Ercan Büyükbaş, Turkish State Meteorological Service (TSMS)

Radars now used to Verify NWP model Precipitation forecasts

Observational issues

Transition to BUFR for radiosondes provide new opportunities GPS total zenith delay gobal coverage Contribution to GOS by nations increasing (e.g. FY-3, Oceansat-2) to fill future gaps in GOS.Further delay in ESA wind lidar In-situ soil moisture and temp Common format for rain radar data.To improve estimates of solid precipitation and develop guidance on the accuracy and temporal resolution of solid precipitation parameters.New observations needed for convective scale models

There is increasing evidence based upon results from A-TREC, TPARC, AMMA (in the form of OSEs, adjoint-based observation impact studies, and analysis uncertainty estimates) to recommend, if feasible, increases in observations from:

• Commercial aircraft over the N. Pacific, N. Atlantic, and the S. Hemisphere in general.

• Additional soundings from certain coastal radiosondes, including those in eastern Siberia, and perhaps selected stations in polar regions, Africa, and South America.  

to improve NWP forecasts in the 2-5 day timeframe.

DAOS-WG statement on need for DAOS-WG statement on need for additional in-situ observationsadditional in-situ observations

4D error covariancesTemporal covariance evolution (explicit vs. implicit evolution)

EnKF and 4D-Ens-Var:

4D-Var and Ens 4D-Var:

-3h 0h +3h

96 NLM integrations

55 TL/AD integrations,2 outer loop iterations

Forecast Results:En-4D-Var vs. 4D-Var-Bnmc

Difference in stddev relative to radiosondes:

Positive En-4D-Var better

Negative 4D-Var-Bnmc better

zonal wind

temp.

height

north tropics south

Targeted Observations for Improving Numerical Weather

Prediction: An OverviewS. J. Majumdar (RSMAS/U. Miami)

R. Saunders, P. Gauthier (DAOS WG Co-Chairs)S. Aberson, C. Bishop, C. Cardinali, J. Caughey, A.

Doerenbecher, R. Gelaro, T. Hamill, R. Langland, A. Lorenc, T. Nakazawa, F. Rabier, C. Reynolds, Y. Song, Z. Toth, C. Velden, M. Weissmann, C.-C. Wu plus contributions from

past and present DAOS WG membersManuscript in preparation for WMO Report and BAMS

A. Doerenbecher, Météo France

The targeting

procedure

Impact of dropsonde data5 day NCEP forecasts

No dropsonde With T-PARC Dropsondes

Verifying analysis

Impact of dropsonde data for Irene

Comparison of different models

Tropical cyclone track forecast errors during the Summer T-PARC period for four assimilation-forecast systems. The solid (dashed) lines represent parallel analysis-forecast cycles excluding (including) T-PARC dropwindsonde data.

DAOS-WG Statement on impact of targeted dataMid-Latitude Systems

• For extratropical systems, the value of targeted data is found to be positive but small on average when evaluated over continental or hemispheric areas. In observing system experiments using aircraft data from field experiments, the results are mixed; while the Atlantic A-TReC study found very little impact from targeted observations, the ongoing Winter Storms Reconnaissance (WSR) programme has found that targeting results in some improvement in 2-3 day forecasts over N. America.

•Observations that sample dynamically sensitive areas have a bigger average impact per observation than those deployed randomly. However, unless these observations cover the entirety of the sensitive regions regularly, which is rarely the case, they cannot be expected to have a large systematic impact on the forecasts. The cumulative benefit of a small number of targeted aircraft observations to forecast accuracy over broad verification regions is smaller than that of other observing systems that provide observations with a more complete coverage.

•The justification of significant expenditure, for instance for a dedicated aircraft system dropping sondes, requires statistically significant results from well designed experiments. These do not currently exist in published papers for mid-latitude synoptic-scale NWP.

DAOS-WG Statement on impact of targeted dataTropical Cyclones

• For forecasts of the track of TCs targeted observations have proven to be beneficial statistically. The benefit to society is also more straightforward to define than for mid-latitude weather. A simple sampling strategy of observing uniformly around the TC has been shown to be effective, with most models exhibiting an improvement. However, the quantitative benefit differs from model to model, due in part to their respective treatment of routinely-available satellite and aircraft observations in their assimilation schemes.

• Recent studies have demonstrated that observations targeted for TCs can also improve the skill of forecasts in distant regions. The mechanisms behind how TC forecasts are improved, and can be improved further, by targeted observations are still being investigated.

DAOS-WG Statement on impact of targeted dataFuture Directions

• There is a need to assess the impact of targeted observations with more user-focused measures of the value of forecast improvements to society, while retaining the ability to get significant results from relatively short experiments.

• The ongoing move away from deterministic forecasts toward probabilistic forecasts means the scores should reflect reductions in initial condition uncertainty introduced through targeted observations, and the subsequent impact of these reductions on forecast uncertainty. •Targeting has mostly been to improve short-range forecasts. A few studies for medium and long-range forecasts have given mixed results. In some studies, targeted observations made negligible differences to forecasts downstream, while others gave positive impacts in both mid-latitudes and tropics. More research is needed.

•

DAOS-WG Statement on impact of targeted dataFuture Directions (2)

• Given that we depend on the cumulative effect from many observations to have a positive average impact, broader-scale, regime-based sampling (e.g. adaptive use of satellite data) may be an effective method for ameliorating the sampling issue and increasing the impact of targeted observations on both short- and extended-range forecasts.

• The development of a better theoretical basis for quantitatively predicting and evaluating the error variance reduction due to any potential deployment of targeted observations should result in their more effective use.

•Targeting for the mesoscale with mobile observational systems is still in its infancy and needs further development. Potential examples include targeting a mobile mesonet for forecasts of severe weather, and airborne Doppler radar for forecasts of TC structure and intensity.

DAOS-WG Future Directions• Leading group for DA in WMO together

with WGNE. Future role in WWRP?

• Links with ET-EGOS, SPARC, GLASS

• Joint meeting with MFWR under discussion

• DAOS remains a global focus not mesoscale

• Continue mix of Observations and DA