Esa Standard document...scene, one chirp is extracted from the beginning, and one at the end of the auxiliary data to be processed. No more available 3.2.4 UWA Power spectrum in polar

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Cyclic_Report_76.doc

fD O C U M E N TD O C U M E N TD O C U M E N TD O C U M E N T

document title/ titre du document

ERSERSERSERS----2 SAR C2 SAR C2 SAR C2 SAR CYCLIC YCLIC YCLIC YCLIC RRRREPORTEPORTEPORTEPORT

CCCC Y C L E Y C L E Y C L E Y C L E 7 67 67 67 6

F R O M F R O M F R O M F R O M 2 2 2 2 2 2 2 2 J U L J U L J U L J U L 2 0 0 2 2 0 0 2 2 0 0 2 2 0 0 2

T OT OT OT O

2 6 2 6 2 6 2 6 A U G A U G A U G A U G 2 0 0 22 0 0 22 0 0 22 0 0 2

prepared by/préparé par PCS team issue/édition 1 revision/révision 0 date of issue/date d’édition status/état Draft Document No

ERS-2 SAR Cyclic Report issue 1 revision 0 -

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A P P RA P P RA P P RA P P R O V A LO V A LO V A LO V A L

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issue issue

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author auteur

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approved by approuvé by

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C H A N G E L O GC H A N G E L O GC H A N G E L O GC H A N G E L O G

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C H A N G E R E C O R DC H A N G E R E C O R DC H A N G E R E C O R DC H A N G E R E C O R D

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TTTT A B L E A B L E A B L E A B L E OOOO F F F F CCCC O N T E N T SO N T E N T SO N T E N T SO N T E N T S

1 DISTRIBUTION LIST................................................................................................................5

2 INTRODUCTION AND SUMMARY ..........................................................................................5 2.1 Summary ............................................................................................................................................5 2.2 UI16 Analysis ....................................................................................................................................5 2.3 UIND Analysis...................................................................................................................................5 2.4 UIC Analysis......................................................................................................................................6 2.5 UWA Analysis ...................................................................................................................................6 2.6 UWAND Analysis .............................................................................................................................6 2.7 QCP Analysis .....................................................................................................................................6 2.8 Transponders in Flevoland.................................................................................................................6

3 DEFINITION OF PRODUCTS...................................................................................................7 3.1 Offline SAR Data Products Format Standards...................................................................................7

3.1.1 SAR PRI.....................................................................................................................................7 3.1.2 QCP............................................................................................................................................7

3.2 Fast Delivery Ground Station Products Format Standards ................................................................7 3.2.1 UI16 ...........................................................................................................................................8 3.2.2 UIND..........................................................................................................................................8 3.2.3 UIC.............................................................................................................................................8 3.2.4 UWA ..........................................................................................................................................8 3.2.5 UWAND ....................................................................................................................................8

4 SAR CALIBRATION.................................................................................................................9 4.1 Calibration over Flevoland.................................................................................................................9

4.1.1 Antenna Pattern Correction over the Rain Forest ....................................................................10 4.1.2 SAR Unavailability for Thermal Calibration of the AMI........................................................10 4.1.3 SAR FD Production requirements for QA and payload monitoring........................................10 4.1.4 Flevoland site ...........................................................................................................................11 4.1.5 Transponders ............................................................................................................................11

4.2 Calibration over rain forest ..............................................................................................................11

5 SAR PERFORMANCE ...........................................................................................................16 5.1 AMI unavailability ...........................................................................................................................16 5.2 SAR/Wave acquisition.....................................................................................................................17 5.3 Platform attitude evolution...............................................................................................................18

5.3.1 Attitude monitoring processing................................................................................................18 5.3.2 Doppler,Yaw and pitch evolution ............................................................................................19

5.4 Doppler map plot..............................................................................................................................21


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s 5.5 ERS-2 AMISAR Image/Wave Mode Operation Report ..................................................................24 5.6 ERS-2 SAR Wave Mode Operation Cyclic Report .........................................................................24

6 REPLICA TREND ANALYSIS................................................................................................26 6.1 QCP analysis ....................................................................................................................................26

7 CALIBRATION PULSE TRENDS...........................................................................................28 7.1 UWAND analysis.............................................................................................................................28

8 PRODUCTS QUALITY ANALYSIS ........................................................................................29 8.1 Summary of rejected products during the cycle...............................................................................29 8.2 Summary of Product quality anomalies ...........................................................................................29


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1 DISTRIBUTION LIST This report is available in PDF format at the Internet address: http://earth1.esrin.esa.it/f/eeo4.69/ eeo4.71

2 INTRODUCTION AND SUMMARY

2.1 Summary This report summarises the results of the analysis carried out during the cycle 61 (12/02/01 - 19/ 03/01) using the ERS UI16 headers (UISP), UIC, UIND, files produced by the FDP1 processor in Fucino, then UWA and UWAND files produced by the LRDPF processors in Kiruna, Maspalomas, Gatineau and Prince Albert and sent automatically to ESRIN PCS. The calibration site is Flevoland (The Netherlands). The transponders have been monitored to control the stability of the ERS systems. VMP PRI products corresponding to Flevoland acquisi-tions have been also processed and analysed.

2.2 UI16 Analysis (The UI16 headers (UISP) are no longer regularly available since the UI16 product was discontin-ued from planned production starting January 1999, at the beginning of cycle 39. Analysis of IU16, UIND and UIC has been dependent on occasional and contingent productions until December 1999, when production was finally discontinued).

2.3 UIND Analysis Noise power level and the Calibration Pulse power level data are no longer available for analysis through the regular High Rate Fast Delivery channel. Please refer to note 1 for more info.

The UIND analysis is subsituted by the analysis of QCP files, see paragraph 2.7.

1The Product Control Service (PCS-ESRIN-SAE, Rome) has carried out the monitoring of the ERS-SAR High Rate (HR) Fast Delivery (FD) data products, since the beginning of the ERS missions (1991 for ERS-1 and 1995 for ERS-2). Due to the non-Y2K compliance of the Fast Delivery Processor (FDP), installed at the ESA ground stations, no SAR HR FD products (UIND, UIC, UISP) have been available after December 1999. An alternative solution has been chosen for the monitoring of the SAR HR data processing using an extract of the telemetry of each HR (off-line) data products generated at the Italian and United Kingdom Processing and Archiving Facility (I-PAF &UK- PAF).


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s 2.4 UIC Analysis The Replica Pulse power data is no longer available for analysis through the regular High Rate Fast Delivery channel. Please refer to note 1 for more info.

2.5 UWA Analysis The percentage of acquisition warnings at Kiruna is less than 20 %, and there was no occurrence of empty products.

2.6 UWAND Analysis The calibration pulse power is stable with respect to the previous cycle, and it is now about 23.45dB. The slope of the power loss is about –0.00966dB/cycle for year 2002. Please see Figure 10 page 12 for trend plots.

2.7 QCP Analysis The noise power level is stable with respect to the previous cycle, and it is now around 23.61 dB. The calibration pulse power decreases with a slope of –0.05658dB/Cycle at the start of the acquisition and –0.00515dB/cycle at the end for year 2002. The level is now over 42dB at both start and end of the acquisition. The replica pulse power decreases with a slope of –0.072dB/Cycle. The level is level is now over 47.5dB at both start and end of the acquisition for year 2002. Please see Figure 9 page 12 for trend plots.

2.8 Transponders in Flevoland A graph is included showing the calibration constant measured from the transponders in Flevoland. The last acquisition included corresponds to November the 26th, 1999. Transponders 3 is no longer visible, only transponder 2 is visible.


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3 DEFINITION OF PRODUCTS

3.1 Offline SAR Data Products Format Standards

This includes, for the current purposes, the following product:

• SAR Precision Image (SAR.PRI)

• QCP : Quality Control Products

3.1.1 SAR PRI

Multi-look, ground range, digital image generated from raw SAR image mode data using up-to- date (at the time of processing) auxiliary parameters and corrected for antenna elevation gain and range spreading loss. SAR PRI has been specified for users wishing to perform application-orient-ed analysis. It is intended for multi-temporal imaging and to derive radar cross sections. Engineer-ing corrections and relative calibration are applied to compensate for well-understood sources of system variability.

3.1.2 QCP

For each HR data products generated at the Italian Processing and Archiving Facility (I-PAF, Matera), an extract of the telemetry is formatted as an ascii file is produced.These new data products, known as Quality Control Products also referred as QCP, substitute the previous UIND (calibration pulses & noise samples) and UIC (Replica pulses) data products generated by the "old" SAR FD processor.

3.2 Fast Delivery Ground Station Products Format Standards

Fast delivery products include all products that are disseminated over an electronic telecommu-nication link from the Stations or from EECF. This includes, for the purposes of this SAR-Wave document, the following products:

• AMI Image-16 bit (UI16)

• AMI Image Noise Statistic and Drift Calibration (UIND)

• AMI Image Chirp Replica (UIC)

• AMI Wave (UWA)


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s • AMI Wave Noise Statistic and Drift Calibration (UWAND)

3.2.1 UI16

SAR fast delivery image.

3.2.2 UIND

The product contains mean magnitude and standard deviation of the extracted noise data, and four calibration pulses. (The data for one single product can be extracted either at the beginning or at the end of a measurement sequence). No more available since

3.2.3 UIC This product contains two chirps. i.e. two sets of samples of the transmitted pulse. For each image scene, one chirp is extracted from the beginning, and one at the end of the auxiliary data to be processed. No more available

3.2.4 UWA

Power spectrum in polar coordinates. The power spectrum is based on a sample of data covering an area of at least 5 x 5 km. The instrument on the satellite collects data at intervals of approximately 200 to 300 km. The sample patch may be anywhere in the 100-km wide swath in the order of 2-km steps. Input for this product can be OBRC or OGRC data.

3.2.5 UWAND

Mean magnitude and standard deviation of the noise data, as well as four calibration pulses, ex-tracted at the beginning of a measurement sequence (scene), every 15th scene.


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s 4 SAR CALIBRATION

The SAR CAL/VAL plan is expressed relatively to the 35-day repeat cycle and shall be translated periodically for each ERS-2 mission cycle.

4.1 Calibration over Flevoland The following requirements apply to ERS-1 and ERS-2 missions. The SAR calibration site is in Flevoland (The Netherlands), with 3 transponders having the fol-lowing coordinates:

Transponder Latitude Longitude 1: Pampushout +52.36651429N +5.15197438E 2: Lelystad +52.45806341N +5.52755628E 3: Minderhout +52.55502077N +5.66896505E

Table 1: Flevoland Transponders coordinates

During one 35-day cycle, there are 3 ascending passes and 3 descending passes that allow taking a SAR Image with at least two of the three transponders:

Transponder Passes ALL 29, 151 1 and 2 301, 423 2 and 3 258, 380

Table 2: Transponder visibility at any given cycle

In order to allow substantial Wind Scatterometer data to be acquired over the North Sea, the re-quirement is to acquire only the frames containing the three transponders, and acquire the ascend-ing one only every 2 cycles.

The detailed acquisition scenario for a cycle is presented in Table 1 on page 9. For each Image selected, a PRI product shall be generated at ESRIN/CPRF and sent to ESRIN/ PCS for QA.

Rel Orbit

Frame Number

Valid Cycle

CYCLE 11 CYCLE 12 CYCLE 13 CYCLE 14 ...

29 1053 EVEN - 5895 6396 6897 151 2547 ALL 5516 6017 6518 7019

Table 3: SAR Calibration over Flevoland


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s 4.1.1 ANTENNA PATTERN CORRECTION OVER THE RAIN FOREST

Every six months average, SAR data in ascending and descending pass shall be acquired over the Amazon Rain-Forest for antenna pattern monitoring. The data will be acquired at the station of Cuiaba (Brazil) and shipped to ESRIN/CPRF for processing.

The set to be acquired consists of two ascending orbits and two descending ones (cycle/frame de-tails in Table 4, page 10). This set shall be acquired every 5 cycles in average.

4.1.2 SAR UNAVAILABILITY FOR THERMAL CALIBRATION OF THE AMI

Twice a year, one 24-hour period of operations without any SAR image shall be scheduled around the solstice (+- 10 days) for payload thermal control and calibration purposes. This period shall be selected during working days and shall start at around mid-day. The choice will be coordinated between ESRIN and ESOC in order to minimise the impact on the SAR mission.

4.1.3 SAR FD PRODUCTION REQUIREMENTS FOR QA AND PAYLOAD MONITORING

Regular production of UI16 shall be performed at the stations for routine payload monitoring:

One UI16 per day in average shall be produced at Maspalomas, Fucino and Kiruna. Together with every UI16 production, UIC and UIND production shall be scheduled and a production report shall be issued and sent to ESRIN/PCS. The generated UI16 products shall be disregarded. UICs and UINDs shall be disseminated via land-lines to ESRIN/PCS. This production compiled along time shall reflect the full station coverage. If this production conflicts with other specific requests over the production period, it shall be descoped.

Rel

Orbit First Frame

Last Frame

Valid Cycle

CYCLE 12

CYCLE 17

CYCLE 22

CYCLE 27

.. .

Asc. Asc.

146 375

6939 6939

7173 7173

5n + 2 5n + 2

6012 6241

8517 8746

11022 11251

13527 13756

Desc. Desc.

139 411

3609 3609

3843 3843

5n + 2 5n + 2

6005 6277

8510 8782

11015 11287

13520 13792

Table 4: SAR Antenna Pattern Correction Acquisitions over the Amazon Rain-Forest


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s 4.1.4 FLEVOLAND SITE

4.1.5 TRANSPONDERS

4.2 Calibration over rain forest The Antenna Pattern monitoring over Amazonian Rain Forest allows to investigate anomalies in the application of the current VMP antenna pattern. Five images have been selected over this area for cycle 75. The characteristics of these images are summarised in the following table:

Scene Orbit - Frame Acquisition date Centre lat/lon (deg) Image mean (dB)

1 37575 – 7047 (ascending) 28-Jun-2002 03:13:21.678 Lat: -7 Lon: 292.533 -7.161

2 37575 – 7065 (ascending) 28-Jun-2002 - 03:13:36.736 Lat: -6.107 Lon: 292.334 -6.889

3 37804 – 7029 (ascending) 14-Jul-2002 - 03:10:05.267 Lat: -7.9 Lon: 293.458 -7.139

4 37840 – 3735 (descending) 16-Jul-2002 - 14:45:46.479 Lat: -6.475 Lon: 292.028 -6.852

5 37840 – 3753 (descending) 16-Jul-2002 - 14:46:01.542 Lat: -7.368 Lon: 291.829 -6.944

Table 5: Selected Rain Forest scenes

Non-uniform regions have been masked in order to perform the antenna pattern monitoring. The analysis results over the selected scenes are reported in the figures below. Figure 1 and figure 2 show the antenna patterns derived from each selected scene, in ascending and descending passes, superimposed; results show a small variation in the measured pattern. The pattern obtained from these images combined is shown in figure 3, with the current VMP antenna pattern.The profiles match each other very closely.


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Figure 1: Measured AP – Orbit 37575, frames 7047-7065, orbit 37804, frame 7029 (ascending passes)

Figure 2: Measured AP – Orbit 37840 frames 3735-3753 (descending passes)


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Figure 3:Measured AP combination (red line) plus reference AP (green line)

The gamma profile for the selected scenes is shown in the figures below. The delta gamma absolute value is low for the analysed scenes, showing a good approximation of the actual antenna pattern. The absolute calibration has been checked referring the mean gamma value. It's about -6.4 dB for all images that is the expected value over Rain Forest.


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Figure 4: Gamma profile - orbit 37575, frames 7047 and 7065, orbit 37804,

Orbit 37575, frame 7047 mean gamma: -6.808 dB



frame 7029 (ascending passes)


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Figure 5: Gamma profile - orbit 37840, frames 3735 and 3753




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5 SAR PERFORMANCE The instrument performances are assessed monitoring the following parameters:

• Acquisition Percentage: the percentage of products in AMI SAR Image/Wave Mode either for cycle 48 and since the beginning of the mission. It is useful to determine the capability of the instrument in performing planned vs. operational meaningful measurements.

• Internal Instrument Parameters for cycle 48. It is important to keep track of the status of

every subsystem internal to the instrument, try to establish correlation with eventual variations in the measured quantities (e.g. range, sigma_0 and significant wave spectra) and with instrument malfunctioning.

5.1 AMI unavailability Instrument From To Comment AMI 17-06-2002 13:16:48 17:50:15 AMI emergency switch down AMI 22-06-2002 08:30:38 173 13:15:50 228 ICU REQ anomaly AMI 04-07-2002 17:44.24 17:51.53 payload synchronization AMI 24-07--2002 11:40:02 15:10:50 228 ICU REQ anomaly AMI 25-07-2002 00:30:40 04:48:59 MCMD refuse mode and heater mode

Table 6: Summary of AMI unavailability


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s 5.2 SAR/Wave acquisition


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s 5.3 Platform attitude evolution Since the end of cycle 72, the platform attitude is piloted efficiently by the ZGM/YCM2 mode. The yaw is well constrain between ±3 degrees and the Doppler3 between ±4500 Hz, see Figure 6 and Table 7 for trend plots and statistics over this cycle. From last cycle, the Doppler bias had decrease by –730Hz with almost the same standard deviation. This also visible on the yaw for which the bias had decrease by 0.32deg and the pitch by –0.5deg.

5.3.1 ATTITUDE MONITORING PROCESSING

The overall process can be described as follows:

1) Wave products Doppler unwrapping: All the UWA products are sent in near real time from dump station to ESRIN/PCS. The attitude parameters are derived and a simple unwrapping is performed on the Doppler. After a data gap the Doppler is reset to the baseband. Therefore, discontinuities are expected for gaps.

2) Data gap interpolation:

Doppler discontinuities for data gaps are corrected by linear interpolation and minimisation of the difference between the extrapolated curves at the gap centre. All the orbits after the gap are corrected with the estimated Doppler offset until a new gap is encountered.

3) Offset correction:

After the second level, the Doppler is almost continue but still subsist an unknown offset due to the fact that the reference for unwrapping in the first/second level is a relative Doppler. The only way (up to now) to correct this offset is the use of Doppler frequencies derived from HR SAR products, since the HR SAR processor (VMP) provides an absolute Doppler frequency estimation.

2 ZGM/YCM: Zero Gyro Mode / Yaw Control Monitoring 3 The Doppler 3rd level correction is available online at http://earth.esa.int/pcs/ers/sar/doppler/doppler_query/


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5.3.2 DOPPLER,YAW AND PITCH EVOLUTION

Figure 6:Doppler, Yaw and pitch 3rd level correction evolution

Mean Std. Dev. Doppler [Hz] -697.837 2732 Yaw angle [deg.] 0.0044 2.349 Pitch angle [deg.] -0.14 0.55

Table 7: Statistics of 3rd level correction attitude parameters.


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s 5.3.3 DOPPLER AND YAW CYCLIC DIFFERENCE EVOLUTION


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5.4 Doppler map plot

Figure 7:Doppler evoluti.on for ascending passes


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s Figure 8:Doppler evolution for descending passes


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s 5.5 ERS-2 AMISAR Image/Wave Mode Operation Report

5.6 ERS-2 SAR Wave Mode Operation Cyclic Report

6


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7


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s REPLICA TREND ANALYSIS

7.1 QCP analysis

Figure 9: Evolution of Replica, calibration and noise pulses from Quality Control Products


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s Start End Mean Std. Dev. Mean Std. Dev. Replica pulses 46.34 8.16 40.55 17 Calibration pulses 28.67 19.2 37.11 11.9 Noise pulses 4.72 3.16 10.91 5.52

Table 8: Statistics of QCP parameters given in dB


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8 CALIBRATION PULSE TRENDS

8.1 UWAND analysis

Figure 10: Evolution of Mean Calibration Pulse Power

dB

Mean Std. Dev. Scaled mean cal.

pulse power 23.61 0.88


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s Table 9: UWAND Calibration Pulse Power statistics

9 PRODUCTS QUALITY ANALYSIS This activity is principally dedicated to the user support. The two main types of activities are:

• Verification of products with a high Doppler value (rejected products) • Product quality/format anomalies

9.1 Summary of rejected products during the cycle Rejected products are those having Doppler Centroid frequencies outside the interval [-4500,4500] Hz. In this case VMP ambiguity estimation is not realiable so the product’s focusing has to be checked. The table below reports the number of rejected products for the current cycle and the percentage of the accepted rejections. Rejected products number Accepted rejections Refused rejections Rejection %

12 2 10 16%

Table 10: Rejected products summary

9.2 Summary of product quality anomalies Products quality anomalies are detected internally or via the users complaints. The action is to analyse the faulty products and report the analysis results. The table below reports the total number of complaints treated for the current cycle with a brief description of the analised problem. Complaints number Complaints description

1 1. Verification of baseline values for three SAR.SLC couples.

Table 11: Users complaints summary

Documents

Esa Standard document...scene, one chirp is extracted from the beginning, and one at the end of the auxiliary data to be processed. No more available 3.2.4 UWA Power spectrum in polar