ALOS PALSAR CYCLIC REPORT 09 MARCH 2008 TO 24 APRIL 2008 · Cyclic Report 18 Cycle Start 09 March 2008 Cycle End 24 April 2008 The main issues during this cycle have been as follows:

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PALSAR_CR_18_080309_080424

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ALOS PALSAR CYCLIC REPORT

09 MARCH 2008 TO 24 APRIL 2008

PUBLIC SUMMARY

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Technical Note

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A P P R O V A L

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ALOS PALSAR Cyclic Report – Cycle 18 � � � � ��

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ALOS QC SAR Team � � ��

09 May 2008

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C H A N G E L O G

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Initial Issue 1 0 09 May 2008

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T A B L E O F C O N T E N T S

1 INTRODUCTION...............................................................................................................5 1.1 Acronyms and Abbreviations ....................................................................................................... 5 1.2 Reference Documents................................................................................................................... 5 1.3 Background Information............................................................................................................... 6

2 SUMMARY........................................................................................................................7

3 SOFTWARE AND AUXILIARY FILE VERSION CONFIGURATION................................8

4 PDS STATUS....................................................................................................................9 4.1 Planned Instrument Unavailability................................................................................................ 9 4.2 Unplanned Instrument Unavailability ........................................................................................... 9 4.3 Current Platform Status ................................................................................................................ 9 4.4 ADEN PDS Unavailability ........................................................................................................... 9 4.5 Periods of missing precision orbit data.......................................................................................... 9 4.6 Periods lacking Yaw Steering ....................................................................................................... 9 4.7 JAXA Observation Strategy ......................................................................................................... 9

5 DATA QUALITY CONTROL...........................................................................................10 5.1 Instrument related anomalies .......................................................................................................10 5.2 Processor related anomalies.........................................................................................................10 5.3 Daily Report Issues .....................................................................................................................10 5.4 User Queries................................................................................................................................10

6 CALIBRATION/VALIDATION ACTIVITIES AND RESULTS..........................................11 6.1 Doppler centroid frequency monitoring .......................................................................................11

6.1.1 Ground station analysis........................................................................................................13 6.2 Point Target IRF Analysis ...........................................................................................................13

6.2.1 Ground station analysis........................................................................................................13 6.3 Distributed Target Analysis .........................................................................................................21 6.4 Noise Equivalent sigma zero .......................................................................................................21 6.5 Radiometric Resolution and Equivalent Number of Looks...........................................................23 6.6 Elevation Antenna Pattern Monitoring.........................................................................................24

6.6.1 African Rainforest Analysis .................................................................................................24 6.7 Localisation Accuracy .................................................................................................................28 6.8 Ambiguities.................................................................................................................................28 6.9 Dual and Quad Polarisation Calibration.......................................................................................28

6.9.1 Co- registration....................................................................................................................28

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6.9.2 Channel coherence, balance and symmetry ..........................................................................28 6.9.3 Cross talk analysis ...............................................................................................................29

6.10 Faraday rotation analysis .............................................................................................................30

7 DISCLAIMERS................................................................................................................32

8 EVENTS..........................................................................................................................33 8.1 Past Events:.................................................................................................................................33

APPENDIX A PALSAR PRODUCT TYPES ............................................................................34

APPENDIX B COHERENCE MEASURES ..............................................................................35

APPENDIX C INSTRUMENT ANOMALIES.............................................................................36

APPENDIX D NATURAL POINT TARGET ANALYSIS...........................................................38

APPENDIX E BEAM NUMBERS.............................................................................................43

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1 INTRODUCTION The PALSAR Cyclic Report is distributed by the PALSAR QC team to keep the PALSAR community informed of any modification regarding instrument performances, the data production chain and the results of calibration and validation campaigns at the end of each ALOS cycle, which represents 671 orbits, or 46 days. The PALSAR instrument is part of the ALOS mission and its products are received and processed via the ADEN ground segment across Europe. A series of quality checks are undertaken in order to assess the ground segment and instrument performance and the product quality. Checks are currently made on a weekly (header parameters, PDS status) or bi-monthly (visual report) basis to have a constant view on the mission status. The cyclic report presents the results of the quality analysis for the different parts of the delivery chain, from satellite to end-product.

1.1 Acronyms and Abbreviations ADEN ALOS Data European Node ALE Absolute Localisation Error ALOS Advanced Land Observing Satellite EO Help Earth Observation Help Desk DN Dynamic Number IRF Impulse Response Function FR Faraday Rotation NRCS Normalised Radar Cross Section OCM Orbit Control Manoeuvre PALSAR Phased Array type L-band Synthetic Aperture Radar PDS Payload Data Segment QC Quality Control SAR Synthetic Aperture Radar SPPA Sensor Performance Products Algorithms SNR Signal to Noise Ratio RCS Radar Cross Section WS Wide Swath

1.2 Reference Documents [1] ALOS PALSAR Product Verification Report, PS-CAL-TN-003, June 2007

[2] Shimada, M., “PALSAR CALVAL Summary and Update 2007”, IGARSS, 2007

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[3] Wright, P., Quegan, S., Wheadon, N. & Hall D., "Faraday Rotation Effects on L-band

Spaceborne SAR Data", IEEE Trans on Geoscience and Remote Sensing, Vol 41, 12, 2003.

[4] Information on ALOS PALSAR Products for ADEN Users, ALOS-GSEG-EOPG-TN-07-0001, April 2007

1.3 Background Information The background information has been extracted from reports issued by ESA during the PALSAR commissioning phase [1]. Information on instrument anomalies and image quality parameters produced during the commissioning phase are quoted here for comparison with the current phase. The PALSAR instrument is a Synthetic Aperture Radar instrument that is part of the ALOS mission built by the Japanese Space Agency (JAXA). The ALOS mission has its data produced and disseminated through geographical nodes. The European node (ADEN) was set up and is operated by ESA through the Tromso, Matera, Mas Palomas and Frascati ground stations. As a third party mission (TPM), only the ground segment and data processing are dealt with by ESA, the platform being the responsibility of the owner: JAXA. Each node operates their ground segment independently and shares results with JAXA when required. The ADEN-ALOS team is responsible for the operation and maintenance of the data received in Europe and North Africa. The ADEN team took part in the Cal/Val activities during the ALOS commissioning phase (January to October 2006). The methodologies used and results obtained are documented in document [1]. Information related to the mission and product are made available to the user through the site: http://earth.esa.int/object/index.cfm?fobjectid=3738 As part of the ADEN operations, a series of quality checks are undertaken in order to assess the ground segment and instrument performance and the product quality for products requested by European users. Checks are currently made on a weekly basis (header parameters, PDS status) to have a constant view on the mission status. Details on the commissioning phase will be placed on the ALOS PCS website, location http://earth.esa.int/pcs/alos/.

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2 SUMMARY Cyclic Report 18 Cycle Start 09 March 2008 Cycle End 24 April 2008 The main issues during this cycle have been as follows: • Visual inspections have highlighted a number of problems with Wide Swath (WS) mode

data, including visible subswath boundaries, scalloping, ADC saturation effects and azimuth ambiguities. Some acquisitions have been processed with inappropriate antenna patterns.

• Interference effects have been identified in several PALSAR images.

• In fine mode and polarimetric mode, the radiometric error at far range is no longer visible in inspected imagery processed with v 4.02 of the processor and above. Azimuth ambiguity effects have also been noted in fine mode data.

• Two fine mode and two wideswath images of the African rainforest has been analysed to assess its suitability for elevation antenna pattern assessment. The fine mode images shows that the elevation antenna pattern has been applied correctly since there is no significant variation in gamma across the swath. The difference in the mean gamma between the two scenes is just 0.06dB indicating that PALSAR was radiometrically stable other the time period of 7 months. This is not the case for the two wideswath images where there are peaks in gamma for certain sub-swaths and an overall trend in gamma across the swath.

• Several images of ground stations within Europe and Africa have been received to determine whether the ground station IRF’s can be used for image quality and stability assessment. The Maspalomas ground station is visible in both fine mode and wideswath imagery although the IRF is saturated in the fine mode imagery because its radar cross-section is very high. This is not the case for the wideswath imagery - the difference in rcs from two wideswath images is just 0.56dB. The Tromso and Matera ground stations both appear to have suitable point targets for IRF analysis in fine mode imagery as they have lower radar cross-sections. Differences in measured rcs values between single and dual polarisation imagery from the same ground station have been found, as was the case when using the DLR corner reflectors (see section 2.1.3). No IRF’s have been found in imagery of the Neustrelitz ground station. The current analysis indicates that the Maspalomas ground station could be used for wideswath mode image quality and instrument stability assessment while the Tromso and Matera ground stations could be used for fine mode image quality and instrument stability assessment. Further imagery will be ordered for all of these ground stations to extend the current analysis.

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3 SOFTWARE AND AUXILIARY FILE VERSION CONFIGURATION

The current processor version of the PALSAR instrument, and the date on which it was installed at each of the stations is detailed in Table 3-1:

Current PALSAR Processor Version ESRIN Matera Tromso

4.03 28/01/08 14/02/08 08/02/08

Table 3-1 PALSAR Processor Version

Prior to these dates, the installed PALSAR processor at each station had been v4.02. A history of the PALSAR processor release notes will be made available on the ALOS ADEN PCS website, location: http://earth.esa.int/pcs/alos/palsar/userinfo.

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4 PDS STATUS

4.1 Planned Instrument Unavailability None

4.2 Unplanned Instrument Unavailability None

4.3 Current Platform Status Information on the platform provided by JAXA: None reported during this cycle.

4.4 ADEN PDS Unavailability None

4.5 Periods of missing precision orbit data For the periods described in Table 4-1, JAXA has announced that precision orbit data is missing.

From (UT) To (UT)

Date Time Date Time Reason

Apr. 4, 2008 21:42:00 Apr. 4, 2008 11:23:00 Due to OCM

Table 4-1 Missing Precision Orbit Data

4.6 Periods lacking Yaw Steering JAXA have not announced any further periods lacking Yaw steering.

4.7 JAXA Observation Strategy The JAXA observation strategy can be found at: http://www.eorc.jaxa.jp/ALOS/obs/overview.htm

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5 DATA QUALITY CONTROL

5.1 Instrument related anomalies ADC saturation effects have been observed in Wide Swath (WS) mode imagery. Interference effects and azimuth ambiguities have also been noted in Wide Swath (WS) mode imagery. The new instrument related anomalies that may have an impact on image quality, radiometric calibration or localisation accuracy during the repeat period are: • Orbit manoeuvres conducted on 4th April 2008.

A full list of anomalies is given in Appendix C.

5.2 Processor related anomalies Version 4.02 of the PALSAR processor appears to have removed the far range radiometric correction error. This situation will continue to be monitored. Visual inspections have highlighted a number of problems with WS mode data including, visible sub swath boundaries, azimuth ambiguities and scalloping. Incorrect antenna patterns have also been observed in wide swath data resulting in across swath variations of up to 3dB (see cycle 15 report for further details).

5.3 Daily Report Issues During the past cycle, daily checks have been undertaken on all PALSAR products generated by ADEN, although reported on a weekly basis due to current data volumes. 95 products have been examined during the course of this cycle, and no issues have arisen from the checks. Of the products which have been visually inspected, none show any evidence of missing lines.

5.4 User Queries A PALSAR FAQ containing the common user requests can be found on the ESA PCS website. The link to this site is: http://earth.esa.int/pcs/alos/palsar/userinfo/

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6 CALIBRATION/VALIDATION ACTIVITIES AND RESULTS

This section gives the results of the calibration/validation activities undertaken during the reporting period.

6.1 Doppler centroid frequency monitoring Figure 6.1 gives the Doppler centroid frequencies of products generated during the cycle, and all previous cycles since April 2007. During Cycle 18, 95 additional products were generated and analysed.

-1600-1400-1200-1000-800-600-400-200

0200400

0 900 1800 2700 3600

Frame

Dop

pler

Cen

troid

Fre

quen

cy (H

z)

Past Data

Cycle 18

Figure 6.1 Doppler Centroid frequency given as a function of the frame number

The Doppler Centroid frequency as a function of position is shown in Figure 6.2 for ascending passes and Figure 6.3 for descending passes.

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Doppler centroid for ascending pass

-90

-70

-50

-30

-10

10

30

50

70

90

-180 -130 -80 -30 20 70 120 170

Past -100 to 0 Hz

Past 0 to 100 Hz

Past 100 to 200 Hz

Past > 200 Hz

-100 to 0 Hz

0 to 100 Hz

100 to 200 Hz

> 200 Hz

Figure 6.2 Doppler centroid frequency for ascending passes

Doppler centroid for descending pass

-90

-70

-50

-30

-10

10

30

50

70

90

-180 -130 -80 -30 20 70 120 170

Past 100 to 0 Hz

Past 0 to -100 Hz

Past -100 to -200HzPast < -200 Hz

100 to 0 Hz

0 to -100 Hz

-100 to -200 Hz

< -200Hz

Figure 6.3 Doppler centroid frequency for descending passes

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6.1.1 GROUND STATION ANALYSIS Several PALSAR products acquired over ground stations within Europe and Africa have been analysed in previous cycles to assess whether the impulse response functions from the ground stations are suitable for image quality and instrument stability assessment. Images of Maspalomas, Spain; Tromso, Norway; Neustrelitz, Germany and Matera, Italy have been ordered and analysed. Results for these ground stations are indicated below.

6.2 Point Target IRF Analysis An analysis of natural point target measurements carried out with PALSAR data is given in Appendix D. No corner reflectors or transponders were available for analysis by the ADEN team in cycle 18. Further stable point target analysis has been performed using the PALSAR ground stations in previous cycles.

6.2.1 GROUND STATION ANALYSIS

Several PALSAR products acquired over ground stations within Europe and Africa have been analysed to assess whether the impulse response functions from the ground stations are suitable for image quality and instrument stability assessment. Images of Maspalomas, Spain; Tromso, Norway; Neustrelitz, Germany and Matera, Italy have been ordered and analysed. Results for these ground stations are indicated below. Maspalomas An image of the Maspalomas ground station complex is shown in Figure 6.2.1 from an ascending pass fine mode image acquired on 6th January 2007, 23:34 UT at 27.7403°N, -15.4281°E, orbit/frame 5075/0540, mode 7 and polarisation HH. The brightest point target is the ESA 15m receiving dish.

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Figure 6.2.1 Image of Maspalomas ground station complex

(ALPSRP050750540_L1.5GER_20070106233404022) The ESA ground station IRF has been analysed - Table 6.2.1 gives the IRF results for the ground station and three other nearby point targets (to the left of the ground station, below/right of the ground station and above/left of the ground station). Target X Y Inc

Ang Azi Res

(m) Range

Res (m) ISLR (dB)

PSLR (dB)

SSLR (dB)

RCS (dBm2)

Ground Station

2482.1 3674.6 37.43 11.23 139.56 0.22 -4.46 -4.45 50.65

1 2521.0 3674.9 37.44 96.17 8.66 -3.78 -2.67 -4.96 41.23 2 2498.0 3737.0 37.44 8.37 7.78 0.45 -5.63 -8.26 34.41 3 2465.0 3636.0 37.42 7.64 7.98 -26.91 -8.46 -10.34 27.16

Table 6.2.1. Maspalomas ground station IRF measurements from 6th January 2007, 23:34UT As the spatial resolution of the ground station and target#1 are much higher than expected, this indicates that the point target is saturated in the product – this is indeed the case. Although target#2 is not saturated it does have a high ISLR due to near by point targets. Only target#4 has an acceptable set of IRF measurements but this has the lowest measured radar cross-section. This target has been identified with a small receiving dish but it is not known whether or not this dish was receiving PALSAR data at the time.

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Thus, although the ESA ground station dish is visible in this PALSAR image, it is heavily saturated within the product. Consequently the measured IRF has very poor spatial resolution in range and high sidelobe ratios. Thus for this PALSAR fine mode image, the 15m ESA ground station has too high a rcs to be of use for IRF and stability assessment. Two wideswath images of the Maspalomas ground station have been analysed. Figure 6.2.2 shows the area around the ground station from a product acquired on 16th April 2007 11:28 UT.

Figure 6.2.2 Wideswath image of Maspalomas ground station

(ALPSRS065263050_L1.5GEC_20070416112856278) As Figure 6.2.2 shows, a point target is visible in the expected location of the Maspalomas ground station, although, given the pixel size of 100m it is not know whether the IRF is due to the ESA ground station or one of its neighbours. The point target IRF has been analysed as given in Table 6.2.2. Note that the IRF is not saturated in the product. The resampled IRF and slices through the IRF are shown in Figure 6.2.3. Target X Y Inc

Ang Azi Res (m)

Range Res (m)

ISLR (dB)

PSLR (dB)

SSLR (dB)

RCS (dBm2)

Ground Station

848.00 2592.75 39.2* 169.10 120.94 -15.07 -8.52 -11.91 55.79

* Estimated value Table 6.2.2 Point Target IRF Parameters

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Figure 6.2.3 Resampled IRF and slices through IRF for the Maspalomas ground station

Figure 6.2.4 shows the area around the ground station from a product acquired on 10th July 2007, 11:39 UT.

Figure 6.2.4 Image of Maspalomas ground station

(ALPSRS077663050_L1.5GEC_20070710113935464)

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As Figure 6.2.4 shows, a point target is visible in the expected location of the Maspalomas ground station. The point target IRF has been analysed as given in Table 6.2.3. Note that the IRF is not saturated in the product. Target X Y Inc

Ang Azi Res (m)

Range Res (m)

ISLR (dB)

PSLR (dB)

SSLR (dB)

RCS (dBm2)

Ground Station

3546.12 2606.88 20.2* 131.65 135.29 0.51 -8.94 -9.01 56.35

* Estimated value Table 6.2.3 Point Target IRF Parameters Note that the difference in rcs between the two wideswath images is just 0.56dB which is encouraging for this ground station to be used for instrument stability assessment in wideswath mode. Tromso Three images of this ground station have been analysed. Figure 6.2.5 shows the area around the expected location of the Tromso ground receiver from a single polarisation fine beam image acquired on 11th January 2007 (6.25m pixels). A point target is visible in the expected location (in the centre of Figure 6.2.5).

Figure 6.2.5 Image of the Tromso ground station

(ALPSRP051461390_L1.5GER_20070111203444277) Figures 6.2.6 and 6.2.7 show the area around the expected location of the Tromso ground receiver from dual polarisation fine beam images acquired on 2nd July 2007 at 20:39 UT and 2nd October 2007 20:38 UT at (both 12.5m pixels). The IRF measurements are given in Table 6.2.4.

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Figure 6.2.6 Image of the Tromso ground station (HH) (ALPSRP076551390_L1.5GER_20070702203909557)

Figure 6.2.7 Image of the Tromso ground station (HH) (ALPSRP089971390_L1.5GER_20071002203851488)

Acq Date

X Y Inc Ang

Azi Res (m)

Range Res (m)

ISLR (dB)

PSLR (dB)

SSLR (dB)

RCS (dBm2)

11/01/07 2774.00 1415.00 37.62 12.03 7.87 1.57 -2.59 -6.21 34.00 02/07/07 1317.00 4389.00 39.90 15.69 16.08 8.18 -6.34 -9.10 41.70 02/10/07 1792.12 4345.00 39.85 18.02 15.36 8.67 -6.58 -3.02 42.74

Table 6.2.4 Tromso Point Target IRF Parameters

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Table 6.2.4 gives the IRF measurements for the three Tromso images. Note that the RCS from the single polarisation product (11/01/07) is quite different from the dual polarisation products. Also note that the rcs of the two dual pol. products are different by just 1dB. It is suggested that further single and dual polarisation products are analysed to compare the rcs values with those in the above table. Neustrelitz Three images of this ground station have been analysed but no IRF is visible in any of these. Matera Three images of this ground station have been received. Figure 6.2.8 and 6.2.9 shows the ground station complex from single polarisation fine beam images acquired on 5th January 2007 at 21:18 UT and 20th February 2007 at 21:18 UT (the pixel size is 6.25m). The point target to the right of the main complex could be a receiving dish. The Matera ground station from a dual polarisation product of 23rd August 2007 21:18 UT is shown in Figure 6.2.10 (12.5m pixels). Again the possible ground station point target is visible - no point target is visible in the cross-polarisation channel. The point target IRF analysis results for the three products are given in Table 6.2.5.

Figure 6.2.8 Image of the Matera ground station

(ALPSRP050590800_L1.5GER_20070105211807628)

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(ALPSRP057300800_L1.5GER_20070220211817725)


(ALPSRP084140800_L1.5GER_20070823211811601)

Acq Date

X Y Inc Ang

Azi Res (m)

Range Res (m)

ISLR (dB)

PSLR (dB)

SSLR (dB)

RCS (dBm2)

05/01/07 6054.00 4023.00 38.84 7.84 7.61 -1.26 -7.83 -8.36 33.03 20/02/07 5722.00 3989.12 38.71 8.53 7.74 -9.41 -7.88 -10.66 31.82 23/08/07 2806.75 2611.12 38.64 21.22 21.22 11.53 -0.79 10.92 28.36

Table 6.2.5 Matera Point Target IRF Parameters

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The results shown in Table 6.2.5 show that the rcs difference for the two single polarisation images (05/01/07 and 20/02/07) is about 1.2dB while the rcs difference of the dual polarisation products is quite larger of at least 3.5dB. It is suggested that further examples of both the single and dual polarisation products are analysed and compared with the above results. Note that JAXA report a radiometric accuracy of 0.64dB compared to a 1.5dB specification and a stability of 0.5-1.0dB from measurements over the Amazon [2].

6.3 Distributed Target Analysis No suitable candidate distributed targets analysed in this cycle. JAXA measurements indicate a stability of 0.5-1.0dB from measurements over the Amazon rainforest [2].

6.4 Noise Equivalent sigma zero Table 6.4.1 gives the noise equivalent sigma zero measures for the products analysed. The table includes all polarisations for which measurements are available. The values are averaged over different beams and product types

Product Mean Noise (dB) Wide swath HH -25.00 Wideswath HV -31.27±1.29 Fine mode HH -21.99±2.11 Fine mode HV -28.59 ±3.64 Fine mode VH -26.13±2.90 Fine mode VV -19.80±0.47

Table 6.4.1 PALSAR Noise equivalent sigma zero measurements by polarisation.

Figure 6.4.1 shows the variation of noise with incidence angle, while Figure 6.4.2 shows the published JAXA results for HH and HV polarisations. A couple of the co-polarisation measurements are above the instrument specification of -23dB. This could be due to measurement of an inappropriate test site, but will continue to be monitored. The cross polarisation measurements are below -25dB.

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Noise measurements

-35

-30

-25

-20

-15

-10

-5

015.00 20.00 25.00 30.00 35.00 40.00 45.00

Incidence angle

Noi

se E

quiv

alen

t S

igm

a0 (

dB)

HVVHVVHH

Figure 6.4.1 Measured Noise equivalent Sigma0 variation with polarization and incidence

angle

Figure 6.4.2 The blue curve is the HH polarisation values and the red curve is the HV

polarisation values [2].

A noise profile in range across the dark mid section of the image in Figure 6.6.2 is shown in Figure 6.4.3, for HV polarisation. These values are compliant with the JAXA specification.

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Figure 6.4.3 Variation in the Noise Equivalent Sigma0 (dB) with range for HV polarisation

for data from orbit 7510, frame 500.

Figure 6.4.4 shows the Noise equivalent Sigma0 over the ocean (image from orbit 8181, frame 840) for HV and HH for FBD mode data. Note that the far range radiometric correction error is no longer present in this data (processed on 24th Jan 2008 at Tromso with processor version 4.02).

Figure 6.4.4. NE Sigma0 (dB) for HV polarisation for FBD mode data from beam 7 (orbit

8181, frame 840)

6.5 Radiometric Resolution and Equivalent Number of Looks Table 6.5 gives the radiometric resolution and the equivalent number of looks for a range of products. The measures quoted are averaged over different beams and polarisations. There are discrepancies between the predicted and measured number of looks for the FBS mode data. This could be due to the use of inappropriate data. Further examples of FBS imagery will be sought to measure the ENL and radiometric resolution. All other fine beam modes now show ENL values close to those expected. The wideswath geocoded products have ENL values a little under that predicted (around 5.4 compared to 8). These radiometric measures will continue to be monitored.

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Product Predicted ENL

Equ. No. Looks(ENL)

Rad Res (dB)

No results

P1.1 1 0.87±0.08 3.17±0.10 9 P1.5GU 4 4.23±0.20 1.72±0.03 4

H1.1(FBD) 1 0.82±0.02 3.24±0.04 2 H1.5(FBD) 4 3.58±0.01 1.84 2

H1.5GU(FBS) 4 1.28±0.34 2.79±0.29 5 H1.5GU(FBD) 4 3.23±0.23 1.92±0.06 4

H1.5U 4 1.02 2.99 1 W1.5P 8 9.62±1.76 1.22±0.10 2

W1.5GP 8 5.36±0.75 1.56±0.09 2 W1.5GU 8 5.44 1.55 1 W1.5P 8 9.69±1.25 1.21±0.07 3

Table 6.5.1 PALSAR measured equivalent number of looks and radiometric resolution.

6.6 Elevation Antenna Pattern Monitoring Fine mode data processed with processor versions prior to V4.02 have a radiometric fall off of around 7dB at far range (see earlier cyclic reports for examples and further details). Users should not use the far range pixels of such products for analysis. Analysis to date indicates that products processed with processor V4.02 are not affected by this problem. Full details of processor installation dates at each processing facility are given in section 3 (a more detailed processor history can be found on the PALSAR PCS website: http://earth.esa.int/pcs/alos/palsar/userinfo/ )

6.6.1 AFRICAN RAINFOREST ANALYSIS

Four PALSAR images of the African Rainforest have been selected to assess its suitability for the estimation of the elevation antenna pattern since a uniform target with isotropic backscattering characteristics is required, which are assumed for tropical rainforests. Since Amazon rainforest data is not available for PALSAR data within the ADEN node, the African rainforest might be a suitable alternative to the Amazon rainforest. The browse images of two ascending pass fine mode product acquired on (i) 21st February 2007, 21:48 UT at 2.909°N, 14.321°E, orbit/frame 5745/0040, mode 7 and polarisation HH and (ii) 9th Octrober 2007, 21:48 UT at 2.908°N, 14.321°E, orbit/frame 9100/0040, mode 7 and polarisation HH are shown in Figure 6.6.1. These two images are acquired exactly 5 repeat periods apart.

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Figure 6.6.1 Browse image of African Rainforest products

ALPSRP057450040_L1.5GEC_ 20070221214839802

ALPSRP091000040_L1.5GER_ 20071009214817982

Although there is more structure visible within this scene than a typical C-band image of the Amazon rainforest image, it should be suitable for elevation pattern estimation. This is because there appears to be no large scale variations within the scene and the pattern is estimated using the whole image. Figure 6.6.2 shows the variation in gamma from near to far range for the two products. There is almost no trend from near to far range indicating that the elevation antenna pattern has been implemented correctly (assuming that gamma follows the same incidence angle variation as the Amazon rainforest). Note that there is no drop-off in gamma in far range as has been found in other PALSAR products. The mean gamma for these two scenes is -5.75dB and -5.81dB respectively. Thus the difference in gamma is just 0.06dB over the time span of just over 7 months, indicating that Palsar was radiometricaly stable over that period of time.

-6.0

-5.9

-5.8

-5.7

-5.6

-5.5

0 2000 4000 6000 8000 10000 12000

Pixels

Gam

ma

(dB

)

Figure 6.6.2(a). Range Gamma profile for the African Rainforest from 21/02/07

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-6.2

-6.0

-5.8

-5.6

-5.4

36 37 38 39 40 41

Incidence Angle (deg)

Gam

ma

(dB

)

Figure 6.6.2(b). Range Gamma profile for the African Rainforest from 09/10/07

Two wideswath images of the African rainforest have also been analysed – these extend the area of the African rainforest analysed above. These are shown in Figure 6.6.3 where the acquisition dates are 22nd June 2007, 09:24 UT (left) and 17th September 2007, 09:18 UT (right).

Figure 6.6.3 Browse image of African Rainforest products

ALPSRS075023550_L1.5GEC_20070622092449490

ALPSRS087713550_L1.5GEC_20070917091809106

Figure 6.6.4 shows the variation in gamma from the central azimuth portion of the 22nd June 2007 scene and from near to far range. There are some variations in gamma across the swath of about 0.5dB – this indicates an incorrectly implemented elevation antenna pattern for some of the sub-swaths. Note that the two bright peaks can also be seen in the full scene in Figure 6.6.3 (left). There also appears to be a drop off at near and far ranges. Overall there is an increase in gamma of about 0.7dB across the swath as indicated by the straight line fit.

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-7.5

-7.0

-6.5

-6.0

-5.5

0 500 1000 1500 2000 2500 3000 3500 4000

Pixels

Gam

ma

(dB

)

Figure 6.6.4 Range Gamma profile for the African Rainforest (HH polarisation)

Figure 6.6.5 shows the variation in gamma from the central azimuth portion of the 17th September 2007 scene and from near to far range. There are some variations in gamma across the swath of about 0.5dB – again this indicates an incorrectly implemented elevation antenna pattern for some of the sub-swaths. Note that the two bright peaks can also be seen in the full scene in Figure 6.6.3 (right). There also appears to be a drop off at near and far ranges. Overall there is an increase in gamma of about 0.7dB across the swath as indicated by the straight line fit. These results are similar to the previous wideswath image.

-7.5

-7.0

-6.5

-6.0

-5.5

0 500 1000 1500 2000 2500 3000 3500 4000

Pixels

Gam

ma

(dB

)

Figure 6.6.5. Range Gamma profile for the African Rainforest (HH polarisation)

Based on the limited analysis of this product, it is encouraging that the fine mode product gamma has no variation across-track indicting that a good elevation antenna pattern has been applied to the data. This appears not to be the case for the two wideswath images where there are variations in gamma for some of the sub-swaths and a gamma slope across the image.

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It is recommended that other fine mode products from different modes are also analysed to assess the applied elevation antenna patterns.

6.7 Localisation Accuracy The ESA ground station at Maspalomas (see section 6.2.1) has been used to assess the image localisation accuracy. For the fine mode image acquired on 6th January 2007, the range absolute localisation accuracy is 68m while the azimuth localisation accuracy is 246m (derived using the image corner coordinates, use of which can result in poorer localisation accuracy than use of the orbit state vectors). JAXA quote a nominal measurement of 9.2m for fine resolution data and 70m for scanSAR data (100m specification). [2]

6.8 Ambiguities JAXA [2] indicate that range ambiguities of -23dB have been observed, compared to a specification of -16dB. Azimuth ambiguities of -11dB have been observed (in both fine and wide swath imagery) in ADEN node data from the 17th May 2007 (compared to a specification of -16dB). Azimuth ambiguities have been measured up to -13.54dB in HV polarisation and up to -15.05dB in HH polarisation for orbit 5728, frame 6760 (acquired 20th February 2007). Further HH ambiguity measurements have been made in this cycle in the range -13.45dB to -14.3dB have been made for a product from orbit 11558, Frame 2800 from the 26th March 2008. Range ambiguities have also been observed in ADEN node data, to date only in fine mode data.

6.9 Dual and Quad Polarisation Calibration Where data is not well calibrated (i.e. residual channel imbalances or high cross talk is measured) there will be an impact on the validity of retrieved geophysical parameters from the data. In this section the polarimetric calibration of the data is assessed.

6.9.1 CO- REGISTRATION

For Level 1.1 polarimetric data the mean channel registration in range is 0.92m (standard deviation 0.8m) and 0.87m in azimuth (standard deviation 1.02m) (i.e. sub-pixel).

6.9.2 CHANNEL COHERENCE, BALANCE AND SYMMETRY

In the following, parameters that may indicate problems with the data calibration are provided in Table 6.9.1. The coherence measures are calculated for level 1.1 polarimetric products only. The measures have been calculated using the Calix tool.

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HV-VH coherence is used for the signal to noise ratio (SNR) calculation. The phase of the HVVH correlation (see Appendix B equ. (2)) is expected to have a zero mean distribution. Deviations from zero mean phase indicate a non compensated phase imbalance in the data calibration. The HV/VH amplitude ratio (see Appendix B equ. (3)) is also expected to have a zero mean distribution. Deviations from zero mean indicate an uncompensated amplitude imbalance. The HHHV and VVVH coherence values should be zero, if greater than 0.3 they indicate the presence of uncorrected cross talk and/or Faraday rotation. If the values are not similar, they indicate a non reciprocal cross talk. A HH-VV (see Appendix B equ(4)) mean phase deviation from zero may indicate uncorrected phase imbalance, depending on the scattering surface. Orbit Frame HVVH

phase Mean

HV/VH amplitude Mean (dB)

SNR

Mean (dB)

VVVH coherence

Mean

HHHV coherence

Mean

HHVV phase. Mean

6940 1260 23.06±24.55° 3.20±5.50 6.14±3.82 0.26±0.11 0.23±0.11 19.26±9.61° 7072 1020 2.17±22.64° -0.16±6.55 1.35±5.76 0.14±0.08 0.17±0.11 6.17±27.69° 6321 2640 3.04±33.07° 0.21±6.53 1.11±6.20 0.20±0.10 0.22±0.11 6.05±26.61° 5650 2640 2.11±21.11° 0.15±5.77 5.31±5.69 0.14±0.08 0.15±0.09 -4.62±23.68° 7024 800 3.12±15.17° -0.09±6.66 1.77±4.51 0.21±0.11 0.23±0.12 3.94 ±10.71° 6474 1080 26.52±22.84° -0.97±7.41 -3.31±2.59 0.19±0.08 0.19±0.07 4.32±7.41° 6575 1380 1.21±2.39° 0.09±4.77 9.80±2.62 0.12±0.06 0.14±0.07 0.02±3.90° 6327 1370 0.91±2.79° 0.05±4.99 8.01±2.65 0.11±0.61 0.14±0.07 -2.04±5.21° 7189 100 24.01±2.00° 3.35±3.96 11.67±1.57 0.10±0.05 0.11±0.06 21.01±10.61° 7233 100 0.90±1.22° 0.25±3.50 12.23±1.81 0.09±0.05 0.09±0.05 -1.58±14.80° 7261 100 3.29±15.28° 0.18±4.39 11.78±4.61 0.10±0.06 0.11±0.06 0.55±6.66° 7276 100 1.08±1.34° 0.05±3.64 11.73±2.07 0.09±0.05 0.1±0.05 7.14±9.55° 6248 2690 4.79±11.6° 0.03±6.33° 3.65±3.72 0.19±0.12° 0.22±0.14° 3.72±14.7°

Table 6.9.1 PALSAR polarimetric coherence measures. The greyed out values are from the previous cycle

6.9.3 CROSS TALK ANALYSIS

Table 6.9.2 gives the cross talk values calculated using SARCON, where: A is the channel reciprocity W is the transmit H to V cross talk U is the receive H to V cross talk V is the transmit V to H cross talk Z is the receive V to H cross talk The cross talk is calculated for polarimetric level 1.1 products only. In general the values are consistent with those measured by JAXA [2] and are as good as or better than the instrument specification of -30dB. Using this technique, areas within the image are selected to perform the cross talk calculation.

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Calculated values (mean) Orbit Latitude Frame A U(dB) Z(dB) W(dB) V(dB)

7072 51.077 1020 0.966 -32.69±4.98 -31.11±0.96 -35.65±2.57 -36.08±4.89 6940 62.286 1260 0.923 -29.68±0.00 -30.24±0.03 -30.81±0.10 -31.64±2.32 6321 48.137 2640 0.862 -21.19±2.38 -25.83±1.51 -23.66±0.54 -31.75±5.07 5650 48.136 2640 0.976 -33.03±0.10 -33.26±1.84 -34.77±2.82 -36.94±0.64 7204 40.248 800 0.829 -26.19±8.43 -31.75±5.71 -25.29±5.76 -29.33±2.89 7189 5.5 100 1.19 -48.57±0.81 -34.44±0.51 -32.43±8.14 -31.25±2.53

Table 6.9.2 Cross talk measured using SARCON for selected image regions

Cross talk measurements are also performed using the CALIX software tool, which uses the entire image to calculate cross talk. These measurements are given in Table 6.9.3

Calculated values (mean) Orbit Latitude Frame

A U(dB) Z(dB) W(dB) V(dB) 7204 40.248 800 0.99 -25.76±6.22 -23.63±6.13 -24.34±6.01 -23.39±5.92 6474 54.004 1080 1.16 -26.98±5.79 -27.43±6.22 -27.75±6.53 -27.83±6.52 6575 68.546 1380 0.94 -28.44±5.66 -27.84±5.47 -27.98±5.5 -27.92±5.55 6327 68.053 1370 0.98 -29.95±5.57 -29.72±5.54 -29.62±5.52 -29.59±5.52 7189 5.500 100 0.75 -24.35±5.47 -24.35±5.48 -24.09±5.44 -24.23±5.45 7233 5.499 100 0.77 -25.10±5.42 -24.99±5.42 -24.99±5.42 -25.16±5.42 7261 5.495 100 0.87 -27.57±5.59 -27.54±5.62 -27.16±5.54 -27.29±5.56 7276 5.500 100 0.9 -26.44±5.45 -26.65±5.43 -25.66±5.43 -26.77±5.43 6248 45.36 2690 1 -25.66±6.27 -23.58±5.86 -24.88±6.12 -23.84±5.64

Table 6.9.3 Cross talk measured using Calix over the entire image.

The mean and standard deviation for the product cross talks measured using the whole image are perhaps slightly worse than those measured from selected sites. In addition the alpha value for product 6474 again indicates that there is a channel imbalance issue with this product.

6.10 Faraday rotation analysis For any given point in the solar cycle, Faraday rotation (FR) is expected to be greatest at mid latitudes, at around 1-2pm local time, and at the equinoxes. Conversely, FR can be expected to be a minimum just before dawn, at polar and equatorial locations and at solstices. These generalisations can be used as a guide to assess whether the calculated FR and FR trends are plausible for a given location and time. Faraday rotation has the effect or rotating the plane of polarisation of the transmitted and received signal. This can result in a much lower return than expected in the co-polarisation channels and a much higher return than expected in the cross-polarisation channel. This reduces the dynamic range of the co-polarised channels and drives the cross-polarised channel to resemble the co-polarised channels. This also reduces sensitivity to ground parameter variations and, for large values of FR, effectively turns a multi-polarisation radar

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into a single-channel system. Information products relying on the classification of L-band HV SAR data, such as crop and forest inventory or land cover maps, are likely to be affected by FR levels exceeding 10°. The accuracies of retrieved geophysical parameters such as soil moisture or vegetation biomass, which require good calibration and data accuracy, will be adversely affected once FR exceeds 5-8° (depending on land cover) [3]. The following measures have been calculated using the Calix tool. Only level 1.1 polarimetric products are used to calculate Faraday rotation.

Orbit Latitude (deg)

Longitude (deg)

Frame Acq. Date UT Local time1

Calculated FR

(deg) 7072 51.077 11.017 1020 23/5/07 21:21 21:50 1.20±0.53 6940 62.286 23.88 1260 14/5/07 20:13 21:26 3.02±0.34 6321 48.137 11.276 2640 2/4/07 10:06 11:06 2.54±1.14 5650 48.136 11.285 2640 15/2/07 10:05 11:06 1.13±1.03 7204 40.248 -3.475 800 01/06/07 22:29 22:00 1.95±0.32 6474 54.004 8.294 1080 12/4/2007 21:28 21:50 0.76±0.24 6575 68.546 27.594 1380 19/4/2007 19:43 21:05 0.95±0.17 6327 68.053 28.538 1370 2/4/2007 19:41 21:18 0.90±0.18 7189 5.500 14.496 100 31/5/2007 21:38 22:26 0.7±0.29 7233 5.499 8.597 100 3/6/2007 22:02 22:26 0.59±018 7261 5.495 37.564 100 5/6/2007 20:06 22:26 0.35±0.2 7276 5.500 27.374 100 6/6/2007 20:47 22:26 0.41±0.16 6248 45.36 11.92 2690 28/3/2007 10:00 11:06 2.5±0.34

Table 6.10 Calculated Faraday rotation. The FR values measured are consistent with those expected for the time of year, day and solar activity. The measures are also within the FR tolerance, hence these images data do not need to be corrected for FR before use in geophysical retrieval. The four equatorial products (Frame 100) provide a baseline mean FR value of 0.51degrees. This provides a measure of the uncertainty in the FR measurement process (the equator is unaffected by Faraday rotation). The non equatorial day time products from around the vernal equinox provide a consistent FR measure of around 2.5 degrees

��

1 Calculated for 22:30 hrs ascending node crossing time and spacecraft nadir at latitude of scene.

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7 DISCLAIMERS During the cycle no disclaimers were issued.

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8 EVENTS The following section details events that may be of interest to ALOS data users.

� The second ALOS PI Symposium will be taking place from the 3rd to the 7th of November in Rhodes, Greece. For more information, please see http:/earth.esa.int/ALOS2008.

o Note that the deadline for abstract submission is June 1st 2008.

� The submission of request files for ALOS simulation number 9 was due by March 21, 2008

8.1 Past Events:

� 29 January 2008: Users are now able to submit orders for ALOS future acquisitions via EOLI-SA (email [email protected] for more information)

� The ALOS PCS Site is now available at:

http://earth.esa.int/pcs/alos/

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APPENDIX A PALSAR PRODUCT TYPES Product identifier Meaning P High resolution polarimetric data W Low resolution wideswath mode data H High resolution single (FBS) or dual (FBD)

polarisation data 1.0 Level 0 – raw data 1.1 Level 1 SLC data 1.5 Level 1 multi-look data G Geocoded P Polar Stereographic projection U Universal Transverse Mercator projection A/D Ascending/Descending

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APPENDIX B COHERENCE MEASURES Cross polarisation coherence measure

1)(11||

: −∗∗

∗

− −=

>><<><=

HVVHVHHVHV

VHHVVHHV SNROOOO

OOγ (1)

Cross polarization phase Imbalance: )OOarg(:� VHHV)VHHV(

∗= (2)

Cross polarisation amplitude imbalance |O||O|

:AVH

HV)VHHV( = (3)

Co polarization phase Imbalance: )OOarg(:� VVHH)VVHH(∗= (4)

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APPENDIX C INSTRUMENT ANOMALIES Below is a list of PALSAR anomalies that may have an impact on image quality, radiometric calibration or localisation accuracy (from 24th October 2006).

� Orbit manoeuvres conducted on 4th April 2008.

� Orbit manoeuvres conducted on 26th January and 2nd, 15th, 29th February 2008.

� YAW steering was suspended on 28th January 2008

� Orbit manoeuvres conducted on 15th December 2007, 4th, 11th & 18th January 2008.

� Observation, yaw steering, and precision attitude system suspended on 31st October

2006 between 03:50 and 15:50 UT due to change AOCS on-board orbit model to that of 15th order.

� Yaw steering suspended during 23rd February 00:12 UT to 24th February 2007 23:01

UT (yaw steering suspended due to calibrating operations for Star Tracker (STT) and Precision Attitude Determination).

� Yaw steering suspended during 22nd March 00:24 UT to 23rd March 2007 23:17 UT

(yaw steering suspended due to calibrating operations for Star Tracker (STT) and Precision Attitude Determination).

� Yaw steering on/off switching on 10th April 2007:

Yaw steering on to off: 12:57 – 13:22 UT (data unavailable) No yaw steering operation: 13:22 – 14:42 UT (data available) Yaw steering off to on: 14:42 – 15:45 UT (data unavailable)

� Orbit manoeuvres on 25th, 27th and 29th April 2007.

� Orbit manoeuvres on 8th and 22nd June 2007.

� Orbit manoeuvres conducted on 7th and 20th July 2007.

� Yaw steering on/off switching on 31st July 2007:

Switching in progress: 00:00 – 00:30, 21:57 – 22:46 UT (Observation suspended) No yaw steering observation: 00:30 – 21:57UT (Data available)

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� An anomalous operation found in PALSAR observations on 23rd March, 12th July, 6th August, 17th August, 21st August, and 23rd August 2007. PALSAR shifted into Standby mode in the middle of the observations. Some of PALSAR data observed during the anomaly are corrupt.

� Orbit manoeuvres conducted on 3rd and 25th August 2007.

� An anomalous operation found in PALSAR observations on 5th September and 8th

September 2007; PALSAR shifted into standby mode in the middle of its observation.

� Orbit manoeuvres conducted on 6th, 12th and 26th October 2007.

� Orbit manoeuvres conducted on 10th and 23rd November 2007.

� Orbit manoeuvres conducted on 7th and 15th December 2007.

� Orbit manoeuvres conducted on 4th, 11th, 18th and 26th January 2008.

� Orbit manoeuvres conducted on 2nd, 15th and 29th February 2008.

� Orbit manoeuvres conducted on 8th March 2008.

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APPENDIX D NATURAL POINT TARGET ANALYSIS Until cycle 16 no point targets (transponder or corner reflectors) with known NRCS have been identified in the PALSAR products analysed at the ADEN Node, natural point targets have been used instead. Table C.1 gives the natural point target NRCS values for a range of PALSAR products analysed during the cycle. Table C.1 gives measurements for the HH polarisation per product type only. This allows measurements from all beams and products to be compared. Table C.2 gives the polarimetric measurements averaged for all beams.

Product/ swath

B3 B7 B9 B18 B21

P1.1 47.76 ±3.87

W1.5P 40.87 W1.5GP 49.39

±5.28 W1.5GU 55.83 52.77

±0.51 H1.1 (FBD)

49.18 ±6.14

H1.5U (FBS)

34.39 ±2.36

H1.5GU (FBS)

34.40 ±2.92

H1.5GU (FBD)

41.04

Table C.1 Average PALSAR Image Radar Cross-Sections per product and beam in HH polarisation.

Table C.2 gives RCS results per polarisation. As there is high NRCS variation across the various polarimetric channels, the results in the table are for strong point targets in each polarisation (i.e. the same point target is not necessarily used to obtain measurements in all four polarisations). Note the polarimetric mode data are all from Beam 3, while the fine mode data are all from beam 7.

NRCS (dB) Product VV

Mean dB HH

Mean dB VH

Mean dB HV

Mean dB P1.1 49.30±6.31 47.76±3.87 41.13±5.91 44.38±5.51 H1.1(FBD) 49.18±6.14 39.18±6.30

Table C.2 Average PALSAR Image RCS per product and polarisation.

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The above measurements indicate typical NRCS values of non-saturated natural point targets that can be derived from PALSAR products. It is not possible to comment on the radiometric accuracy or stability of the natural point target results. Note that JAXA report a radiometric accuracy of 0.64dB compared to a 1.5dB specification and a stability of 0.5-1.0dB from measurements over the Amazon [2]. Tables C.3 & C.4 give the impulse response function (IRF) results for a variety of PALSAR products. In this table results for different polarisations are not segregated. For comparison, the predicted resolution values are also indicated. For fine and polarimetric mode, the resolutions are generally as expected. An exception is the dual polar ground range products where the azimuth resolution is double that predicted. It should be noted however that these products have 12.5 meter pixels. For wide swath mode, the azimuth resolution is higher than the nominal value by about 25-30m while in range the measurements are higher than the predicted values by up to 60m. However, it should be noted that the wide swath pixel size is 100m and thus these differences are not excessive.

Product Azimuth res (m)

Range res (m)

Predicted Azimuth res (m)

Predicted range res

(m)

No. results

P1.1 5.74±1.35 9.97±0.40 4.48 10.71 40 W1.5P 132.2 125.2 100 Fig 6.2.1 1 W1.5GP 126.38±1.20 126.24±4.20 100 Fig 6.2.1 2 W1.5GU 133.50±9.81 124.23±5.61 100 Fig 6.2.1 11 H1.1(FBD) 4.87±0.35 9.75±0.47 4.52 10.71 8 H1.5U(FBS) 9.31±1.11 11.03±2.71 9.04 Fig 6.2.2 7 H1.5GU(FBS) 9.83±0.07 10.56±3.35 9.04 Fig 6.2.2 4 H1.5GU(FBD) 19.38±2.37 19.97±4.14 10.0 Fig 6.2.3 9

Table C.3 Average PALSAR resolution per product type. Note that the wide swath azimuth bandwidth is not available in the product headers therefore the nominal resolution from [2] is quoted.

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WB1

020406080

100120140160180

15 25 35 45

incidence angle

grou

nd r

ange

res

olut

ion

(m)

predictionmeasurements

Figure C.1 Ground range resolution for wide swath mode (WB1) data.

single polarisation- FBS

0

5

10

15

20

25

30

35

0 20 40 60

incidence angle

grou

nd r

ange

res

olut

ion

(m)

predictionmeasurements

Figure C.2 Ground range resolution for FBS data.

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dual polarisation

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60

incidence angle

grou

nd r

ange

res

olut

ion

(m)

Figure C.3 Ground range resolution for FBD data.

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Product ISLR (dB)

PSLR (dB)

SSLR (dB)

No. results

Specification -8.0 -10.0 - - JAXA measure -8.6 -12.5 - - P1.1 -6.25±3.13 - - 31 W1.5P -9.95 -7.76 -13.55 1 W1.5GP -7.15±3.54 -8.03±0.49 -13.11±0.34 2 W1.5GU - -8.28±1.80 -10.89±3.28 5 H1.1(FBD) -5.26±1.84 - 8 H1.5GU(FBS) -2.19±1.38 -7.85±0.17 -5.93±3.71 2 H1.5GU(FBD) -1.16 -12.06±7.79 -11.07±4.52 5 H1.5U(FBS) -3.21±1.55 -8.96±1.59 -13.55±1.77 7 H1.5GU(FBS) -2.19±1.37 -7.85±0.17 -5.93±3.71 2

Table C.4 Average PALSAR sidelobe measures per product type. Note that it has not been possible to measure some of the IRF parameters using natural points. For comparison, the commissioning phase corner reflector measurements [1] are given in Table C.5. In general, the natural point target IRF measurements are as expected.

Product Azimuth res (m)

Range res (m)

ISLR (dB)

PSLR (dB)

SSLR (dB)

1.5(FB) 7.67: 10.5

7.76: 11.23

-9.55 : -1.77

-14.2: -4.99

-15.15: -12.28

1.1(FB) 4.71: 4.78

4.72: 4.78

-8.47 : -5.49

-13.37: -10.84

-20.45: -18.82-

Table C.5 Corner reflector measurement ranges from the commissioning phase [1].

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APPENDIX E BEAM NUMBERS This table has been extracted from [4].