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SMOS In flight system performances assessement avfeter 1 year in orbit

SMOS In flight system performances assessement avfeter 1 year in orbit. F Cabot, A. AlBitar, , P. Richaume, Y.H. Kerr. Reprocessed Data Quality and Stability. L1C assessment Geometry Radiometric accuracy Absolute accuracy Repeat with new antenna model. Reprocessed L1C.

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SMOS In flight system performances assessement avfeter 1 year in orbit

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  1. SMOS In flight system performances assessementavfeter 1 year in orbit F Cabot, A. AlBitar, , P. Richaume, Y.H. Kerr

  2. Igarss '11 - Vancouver Reprocessed Data Quality and Stability L1C assessment Geometry Radiometric accuracy Absolute accuracy Repeat with new antenna model

  3. Igarss '11 - Vancouver Reprocessed L1C The data analysed spans over 1 year of Data (2010) • Madagascar geometry • Dome Concordia • Radiometric accuracy • Absolute brightness temperature accuracy All data have now been processed up to level 2 (SM) and is also investigated over various validation sites  See Monday’s presentation

  4. Igarss '11 - Vancouver Geolocation assessment • Method developped and validated before flight with simulated data • Simple model fit across sharp transition gives access to shift assessment. • Madagascar coastline selected: long linear coastline. • Additional checking being conducted using Earth Horizon ceossing the field of view during external calibration manoeuvre.

  5. Igarss '11 - Vancouver Madagascar Coastline access

  6. Igarss '11 - Vancouver Model fitting results

  7. Igarss '11 - Vancouver Ascending - Descending • Alternate passes are used to constrain geolocation matrix. • Depending on the position of the coast within the swath, this constrain can change.

  8. Igarss '11 - Vancouver Temporal evolution of the geolocation over Madagascar Same technique used as during commissionning, gives less noisy results. All products being processed with same BFP (and correctly applied) std(Ascending) = 350m std(Descending) = 460m Trend is clearer than at the end of IOCPand slightly degradesfinal RMS

  9. Igarss '11 - Vancouver Acquisitions over DomeC Selection of closest DGG node and extraction from L1C products.

  10. Igarss '11 - Vancouver Radiometric Accuracy over Dome C Over 12 months of data, Dome C has been seen more than 200000 times in full pol, spanning the entire EAF Fov. Assuming the target has not changed, we can compute radiometric accuracy as the standard deviation of measured brightness temperature within the FoV. TX TY TX TY T3 T4 Estimated 2.5337 2.3503 4.1970 3.8349 2.8613 3.0761 Computed 2.1181 2.1696 3.4531 3.4724 2.9358 2.9358

  11. Igarss '11 - Vancouver Radiometric Accuracy over Dome C T3 and T4 show some inconsistencies. • Radiometric accuracy as expected • Average TB shows strange behavior

  12. Igarss '11 - Vancouver Tv Domex-2 operative 2009 Th Domex-2 operative 2009 Th Domex-2 Initial 2009 Tv Domex-2 Initial 2009 Tv domex2010 th domex2010 Polarisation signature Dome C only, Hallikainen model (one layer, Tsnow=-54) DomeX data, G. Macelloni

  13. Igarss '11 - Vancouver Absolute brightness temperature accuracy SMOS estimates of TB over Dome C although somewhat noisier, compare well with on-ground measurements

  14. Igarss '11 - Vancouver Bias variations within FoV Different behaviour observed within AF-FoV and EAF-FoV Clear change around april

  15. Igarss '11 - Vancouver Dielectric constants Antarctica: Re and Im *10 + 220 (magenta) ECMWF temperature (blue)

  16. Igarss '11 - Vancouver Stability and radiometric accuracy over Dome Concordia Request for additional statistics and analysis : • Within the field of view • With respect to differential long term drift • METRICS understood as linear temporal trend of average brightness temperature Analysis of reprocessed data set with new antenna model • 2010 from reprocessing • 2010 from selected subset

  17. Igarss '11 - Vancouver Analysis of acquisitions over Dome C

  18. Igarss '11 - Vancouver Long term stability Over 15 months, trends at 42° almost disappears. But only impact of January. Over 2010, drift was -0.22K/yr, now -0.72K/yr with new data set. Std(TB) slightly increase TBH shows signs of a seasonal effect, observed on ground

  19. Igarss '11 - Vancouver Long term stability

  20. Igarss '11 - Vancouver Long term stability in ground reference frame

  21. Igarss '11 - Vancouver METRICS TX TY T3 T4 TX TY T3 T4 TH TV T3 T4 TH TV T3 T4

  22. Igarss '11 - Vancouver Radiometric Accuracy over Dome C Over 15 months of data, Dome C has been seen almost 260000 times in full pol, spanning the entire EAF Fov. Assuming the target has not changed, we can compute radiometric accuracy as the standard deviation of measured brightness temperature within the FoV.

  23. Igarss '11 - Vancouver Radiometric performances

  24. Igarss '11 - Vancouver Radiometric performances 3/4

  25. Igarss '11 - Vancouver New antenna model summary Mixed results for biases correction. • Clear improvement in ground reference frame from may onwards. • Antenna reference frame results unconclusive. • T3/T4 rather unclear, mostly degrades. Marginal gain on radiometric accuracy

  26. Igarss '11 - Vancouver Conclusions • Still homework to be done with • Calibration • Stokes 3 and 4 • Variations within field of view still not totally mastered • But overall performances in radiometry and geolocation out performs specifications • Long term drift starting to be understood ( and thus correction within reach

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