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MODIS Preprocessing (before L1B) Changes over the Last Year (and looking forward)

Explore the recent changes in MODIS preprocessing and look at future adjustments to improve data quality and calibration processes for remote sensing applications.

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MODIS Preprocessing (before L1B) Changes over the Last Year (and looking forward)

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  1. MODIS Preprocessing (before L1B) Changes over the Last Year (and looking forward) Chris Moeller and others CIMSS; Univ. Wisconsin July 13, 2004 Thanks to MCST for their help

  2. MODIS L1B Issues/Changes • Terra RSB Calibration using SD screen down (since June 2003). • DSM RVS implemented for Terra (since 04059) in Collect 5. • Detector/Mirror side TEB destriping. Applied in MOD06, MOD35. No plan for applying to L1B at this time. • Terra MODIS RSB calibration based on trend instead of discrete in Collect 5.

  3. MODIS L1B Issues/Changes • Detector failures in PVLWIR (B28 Det 1, 10). May need to stop using B28 for 5um leak surrogate. • RSB m1 values changing after Day 04158 (mswg040616.ppt). • Change to Terra 5um leak correction (offset forced to zero) for SWIR bands 5,6,7,26. Small impact flows down into B26 correction, causing B26 to be slightly more negative (0-1.4%) after correction for OOB and striping. May be “fixed” by adjusting correction coefficients.

  4. May 6, 2003: the Terra MODIS Solar Diffuser (SD) door telemetry showed an anomaly, indicating the door was not operating. This was found not to be true; however it caused concern about the future operability of the SD door and associated 8% transmission screen. July 2, 2003: decided to operate Terra MODIS with the SD door open and transmission screen in place for remainder of the mission. Courtesy of MCST

  5. The effects are: The SD plate is exposed to sun light on every orbit, hastening degradation of the Spectralon coating. Degradation will be greatest in the blue spectral region; it will be small in longer wavelengths. The degradation will be monitored by SDSM. The RSB calibration is limited to the low signal end by the screen being in place. This accommodates ocean color band calibration at the expense of high signal calibration. Low signal calibration is being used to track calibration change for those bands that previously used high signal calibration.

  6. Courtesy of MCST

  7. Terra MODIS Day 04153 0025 UTC Band 5 1km aggregated Striping appears to be a function of signal. Suggests a calibration slope error. Striping in this image is ~10% of scene signal

  8. RSB calibration (m1) in Terra Collect 5 will be based on trends in SD calibration, not discrete Courtesy of MCST

  9. MODIS Scan Mirror Reflectance Measurement Scan mirror reflectance depends on angle of incidence (AOI) on the mirror Response Vs. Scan (RVS) of Terra MODIS

  10. Terra MODIS Day 03094 1740 UTC Band 35 Old RVS

  11. Terra MODIS Day 03094 1740 UTC Band 35 DSM RVS

  12. Terra MODIS Day 03094 1740 UTC Band 36 Old RVS

  13. Terra MODIS Day 03094 1740 UTC Band 36 DSM RVS

  14. Mirror side “1”

  15. Mirror side “1”

  16. Mirror side “2”

  17. Mirror side “2”

  18. Mirror side “1”

  19. Mirror side “1”

  20. Mirror side “2”

  21. Mirror side “2”

  22. DSM RVS impact on MWIR bands is very small as expected. Brightness Temperature (K) Mirror side “2” Cross Track Frame Number

  23. Mirror side “2” Brightness Temperature (K) DSM RVS impact on PVLWIR bands is typically small except for B29. A scene temperature dependence is also apparent. Cross Track Frame Number

  24. DSM RVS impact on PCLWIR bands is large in atmospheric bands, and small in window bands. Brightness Temperature (K) Mirror side “2” Cross Track Frame Number

  25. Terra MODIS Clear Sky Radiance Bias (MODIS – model prediction) Band 25 (4.54 um) Old RVS

  26. DSM RVS Terra MODIS Clear Sky Radiance Bias (MODIS – model prediction) Band 25 (4.54 um)

  27. Old RVS Terra MODIS Clear Sky Radiance Bias (MODIS – model prediction) Band 34 (13.2 um)

  28. DSM RVS Terra MODIS Clear Sky Radiance Bias (MODIS – model prediction) Band 34 (13.2 um)

  29. Old RVS Terra MODIS Clear Sky Radiance Bias (MODIS – model prediction) Band 35 (13.9 um)

  30. DSM RVS Terra MODIS Clear Sky Radiance Bias (MODIS – model prediction) Band 35 (13.9 um)

  31. Old RVS Terra MODIS Clear Sky Radiance Bias (MODIS – model prediction) Band 36 (14.2 um) The biases have a distinct dependence on scan angle

  32. Terra MODIS Clear Sky Radiance Bias (MODIS – model prediction) Band 36 (14.2 um) DSM RVS Using DSM RVS largely removes the bias dependence on scan angle

  33. MODIS TEB destriping impact • Destripe all MODIS thermal bands using Empirical Distribution Function (EDF). Destriping is done on a granule by granule basis (no knowledge from one granule to next). • Look at change in radiances, including at granule interfaces.

  34. B 22

  35. B 27

  36. B 29

  37. B 34

  38. B 36

  39. Before Destriping

  40. After Destriping

  41. Before Destriping

  42. After Destriping

  43. Figure 1 Red: Median restore on Blue: Median restore off

  44. Brightness Temperature (K) MODIS Scan Line Counter

  45. Brightness Temperature (K) MODIS Scan Line Counter

  46. Brightness Temperature (K) MODIS Scan Line Counter

  47. Brightness Temperature (K) MODIS Scan Line Counter

  48. Brightness Temperature (K) MODIS Scan Line Counter

  49. Brightness Temperature (K) MODIS Scan Line Counter

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