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CryoSat Interferometer
Performance after 5 years in Orbit
Michele Scagliola, Aresys
Marco Fornari, ESA
Jerome Bouffard, ESA
Outline
 Calibration of the CryoSat interferometer
 End-to-end performance and CryoSat requirement on across-track
accur...
Calibration of
CryoSat Interferometer
End-to-end calibration of CryoSat interferometer:
 in orbit calibration campaigns r...
Calibration of
CryoSat Interferometer
End-to-end calibration of CryoSat interferometer:
 in orbit calibration campaigns r...
Calibration of
CryoSat Interferometer
The end-to-end error on the AoA can be modeled as a linear function of the measured
...
End-to-end performance
and CryoSat requirements
The end-to-end performance of the CryoSat interferometer can be evaluated ...
Calibration campaigns:
BaselineC
Analysis of BaselineC CryoSat L1b SARin acquired during the roll campaigns
 below the re...
Calibration campaigns:
BaselineC
Analysis of BaselineC CryoSat L1b SARin acquired during the roll campaigns
 below the re...
Improving the end-to-end
performance
An activity was started aiming at verifying if the end-to-end performance in
the sens...
Calibration campaigns:
aberration correction applied
Analysis of BaselineC CryoSat L1b SARin acquired during the roll camp...
Calibration campaigns:
aberration correction applied
Analysis of BaselineC CryoSat L1b SARin acquired during the roll camp...
End-to-end performance:
operational acquisitions
The end-to-end performance evaluated
on roll campaigns data
The end-to-en...
End-to-end performance:
operational acquisitions
End-to-end performance of CryoSat Interferometer from a dataset of more t...
End-to-end performance:
transponder acquisitions
The improvement in the sense of interferometer performance given by the
a...
Conclusions
 The end-to-end performance of CryoSat interferometer have been within
system requirement from the beginning ...
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CryoSat Interferometer Performance after 5 years in Orbit

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Lps16 scagliola interf_cal

  1. 1. CryoSat Interferometer Performance after 5 years in Orbit Michele Scagliola, Aresys Marco Fornari, ESA Jerome Bouffard, ESA
  2. 2. Outline  Calibration of the CryoSat interferometer  End-to-end performance and CryoSat requirement on across-track accuracy/precision  Improving the end-to-end performance of Cryosat Interferometer by on-ground processing  Conclusions
  3. 3. Calibration of CryoSat Interferometer End-to-end calibration of CryoSat interferometer:  in orbit calibration campaigns rolling left and right the spacecraft of about ±0.4 deg  the purpose is to deternine the across-track slope of the ocean surface First arrival Right antennaLeft antenna q χ P Satellite velocity vector Boresight direction    )/())0(( 0 BkArg  Rh /1 the angle of the first arrival from SARin L1b roll mispointing angle from Star Tracker a geometric factor Ocean surface slope
  4. 4. Calibration of CryoSat Interferometer End-to-end calibration of CryoSat interferometer:  in orbit calibration campaigns rolling left and right the spacecraft of about ±0.4 deg  the purpose is to deternine the across-track slope of the ocean surface  slope of ocean surface is known from geoid The error between the measured angle of arrival (AoA) and the expected AoA from geoid First arrival Right antennaLeft antenna q χ P Satellite velocity vector Boresight direction       geoid m error on the AoA coming from the SIRAL and the IPF1 error on roll coming from star tracker and on ground processing Measured error
  5. 5. Calibration of CryoSat Interferometer The end-to-end error on the AoA can be modeled as a linear function of the measured AoA, so that the interferometer calibration function results in -0.01 -0.005 0 0.005 0.01 -2.4 -2.3 -2.2 -2.1 -2 -1.9 -1.8 -1.7 -1.6 x 10 -3 Measured AoR [rad] ErroronAoR[rad] (q) = -0.025472q -0.0019043  m (q) 0)(   a phase departure [1] roll bias [1] [1] Galin, N.; Wingham, D.J.; Cullen, R.; Fornari, M.; Smith, W.H.F.; Abdalla, S., "Calibration of the CryoSat-2 Interferometer and Measurement of Across-Track Ocean Slope," in Geoscience and Remote Sensing, IEEE Transactions on , vol.51, no.1, pp.57-72, Jan. 2013 By analysis of the data acquired during the roll calibration campaign, the interferometer calibration parameters are computed Interferometer Calibration function ErroronAoA[rad] Measured AoA [rad] 3996.1)588.9()(  ee 
  6. 6. End-to-end performance and CryoSat requirements The end-to-end performance of the CryoSat interferometer can be evaluated on the residual error on the measured AoA after that the calibration function has been applied    0  ammr Residual error  r  rSTD  CryoSat System req. on interferometer Value E2E performance figure Symbol Residual across-track accuracy @2000km 141 μrad absolute average of the residual error on AoA Residual across-track precision @1Hz 60 μrad standard deviation of the residual error on AoA
  7. 7. Calibration campaigns: BaselineC Analysis of BaselineC CryoSat L1b SARin acquired during the roll campaigns  below the requirements  highly dependent on the Star Tracker that provides the roll mispointing information 09-2010 04-2011 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 0 50 100 150 Time [mm-yyyy] Abs.err.[10 - 6rad] 09-2010 04-2011 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 0 10 20 30 40 50 60 70 Time [mm-yyyy] STD[10 - 6rad] 09-2010 04-2011 10-2011 05-2012 11-2012 06-2013 01-2014 0 0 50 100 150 Time [mm-yyyy] Abs.err.[10- 6rad] EECFI STR average EECFI STR1 EECFI STR2 EECFI STR3 End-to-end requirement Residual across-track accuracy Residual across-track precisions  below the requirements  independent of the Star Tracker that provides the roll mispointing information 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 Time [mm-yyyy] EECFI STR average EECFI STR1 EECFI STR2 EECFI STR3 End-to-end requirement
  8. 8. Calibration campaigns: BaselineC Analysis of BaselineC CryoSat L1b SARin acquired during the roll campaigns  below the requirements  highly dependent on the Star Tracker that provides the roll mispointing information  below the requirements  independent of the Star Tracker that provides the roll mispointing information  comparable to Instrument noise at L1B 09-2010 04-2011 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 0 50 100 150 Time [mm-yyyy] Abs.err.[10 - 6rad] 09-2010 04-2011 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 0 10 20 30 40 50 60 70 Time [mm-yyyy] STD[10 - 6rad] 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 Time [mm-yyyy] EECFI STR average EECFI STR1 EECFI STR2 EECFI STR3 End-to-end requirement 09-2010 04-2011 10-2011 05-2012 11-2012 06-2013 01-2014 0 0 50 100 150 Time [mm-yyyy] Abs.err.[10- 6rad] EECFI STR average EECFI STR1 EECFI STR2 EECFI STR3 End-to-end requirement Residual across-track accuracy Residual across-track precisions Instrument noise at L1b
  9. 9. Improving the end-to-end performance An activity was started aiming at verifying if the end-to-end performance in the sense of residual across-track accuracy can be still improved. Following possible improvements have been identified 1. During on-ground processing of Star Tracker data, the aberration of the light can be (properly) corrected: accuracy of the mispointing angle is increased 2. A calibration function different for each Star Tracker can be computed and then applied to SARin L1b data
  10. 10. Calibration campaigns: aberration correction applied Analysis of BaselineC CryoSat L1b SARin acquired during the roll campaigns  much below the requirements  independent on the Star Tracker that provides the roll mispointing information  No degradation applying aberration corr.  independent of the Star Tracker that provides the roll mispointing information 09-2010 04-2011 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 0 10 20 30 40 50 60 70 Time [mm-yyyy] STD[10 - 6rad] 09-2010 04-2011 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 0 50 100 150 Time [mm-yyyy] Abs.err.[10 - 6rad] Residual across-track accuracy Residual across-track precisions 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 Time [mm-yyyy] EECFI STR average EECFI STR1 EECFI STR2 EECFI STR3 End-to-end requirement 09-2010 04-2011 10-2011 05-2012 11-2012 06-2013 01-2014 0 50 100 150 Time [mm-yyyy] Abs.err.[10- 6rad] EECFI STR average EECFI STR1 EECFI STR2 EECFI STR3 End-to-end requirement
  11. 11. Calibration campaigns: aberration correction applied Analysis of BaselineC CryoSat L1b SARin acquired during the roll campaigns  much below the requirements  independent on the Star Tracker that provides the roll mispointing information 09-2010 04-2011 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 0 50 100 150 Time [mm-yyyy] Abs.err.[10 - 6rad] Residual across-track accuracy 09-2010 04-2011 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 0 50 100 150 Time [mm-yyyy] Abs.err.[10 - 6rad] Aberration correction not applied 10-2011 05-2012 11-2012 06-2013 01-2014 07-2014 02-2015 Time [mm-yyyy] EECFI STR average EECFI STR1 EECFI STR2 EECFI STR3 End-to-end requirement
  12. 12. End-to-end performance: operational acquisitions The end-to-end performance evaluated on roll campaigns data The end-to-end performance evaluated on operational BacelineC SARin L1b products achievable end-to-end performance of CryoSat Interferometer Residual error minimized by computation of the Calibration Function operational end-to-end performance of CryoSat Interferometer The accuracy/precision of the SARin L1b that are made available to science users
  13. 13. End-to-end performance: operational acquisitions End-to-end performance of CryoSat Interferometer from a dataset of more than 200 BaselineC SARin L1b products: all SARin L1b products acquired over a SARin patch in Indian ocean, that has been active in operations from Nov. 2010 to May 2012 (about 17 months) Definition E2E Accuracy on AoA [rad] E2E Precision on AoA [rad] Contribution to height error [mm] End-to-end requirement 141 60 14.6 BaselineC SARin L1B 105 32 6.8 Aberration correction applied 57 32 2.9 Aberration correction applied Roll bias function of Star Tracker 21 32 1.0
  14. 14. End-to-end performance: transponder acquisitions The improvement in the sense of interferometer performance given by the application of the aberration correction and by using a roll bias different for each Star Tracker has been verified also by analysis of acquisitions over Transponder Paper 303 - Session title: Cryosphere Posters CRYO-6 - CryoSat-2, SIRAL Calibration with Transponder Garcia-Mondejar, Albert (1); Fornari, Marco (2); Mertikas, Stelios (3); Bouffard, Jerome (4); Roca, Mònica (1) 1: isardSAT Ltd.; 2: ESTEC, ESA; 3: Technical University of Crete; 4: ESRIN, ESA
  15. 15. Conclusions  The end-to-end performance of CryoSat interferometer have been within system requirement from the beginning of the mission  The residual across-track accuracy and precision for BaselineC SARin L1B products has been assessed for science products  Towards BaselineD, the residual across-track accuracy and precision for the SARin L1B products can be still improved during on-ground processing - More accurate mispointing angles can be obtained by applying the aberration correction - A proper roll bias for each Star Tracker can be compensated

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