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GERB/CERES Shortwave and Longwave/Day Comparisons

GERB/CERES Shortwave and Longwave/Day Comparisons. Pamela E. Mlynczak 1 G. Louis Smith 2 Z. Peter Szewczyk 1 1 SAIC Hampton, VA 2 National Institute of Aerospace Hampton, VA. Objectives.

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GERB/CERES Shortwave and Longwave/Day Comparisons

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  1. GERB/CERES Shortwave and Longwave/Day Comparisons Pamela E. Mlynczak1 G. Louis Smith2 Z. Peter Szewczyk1 1SAIC Hampton, VA 2National Institute of Aerospace Hampton, VA 24th GIST MeetingDecember 14-16, 2005

  2. Objectives • To date, we have conducted studies of four major campaigns when CERES was viewing scenes that were coaligned with GERB’s view. • Both pixel-by-pixel and gridded comparisons will be shown of SW unfiltered radiances. • I will also present our comparison of the CERES LW unfiltered radiances with those from GERB. 24th GIST MeetingDecember 14-16, 2005

  3. GERB/CERESSpecial Operations • December 2003/January 2004 15 days • June/July 2004 27 days • December 2004/January 2005 26 days • June 2005 21 days 24th GIST MeetingDecember 14-16, 2005

  4. Criteria for SW Matches – Detector-Based Comparison • Use GERB L1.5 NANRGs for time. • Use RMIB’s unfiltered SW radiances, angles, and geolocations for GERB. • Use CERES Edition 2 Revision 1 ES8s. • View zenith and relative azimuth angles within 5°. • Near GERB subsatellite point, accept matches within 10° angle between GERB & CERES rays. • Shows the ratio of mean GERB SW to mean CERES SW at each GERB detector. 24th GIST MeetingDecember 14-16, 2005

  5. CERES Matches for June 11, 2004 24th GIST MeetingDecember 14-16, 2005

  6. Latitude Coverage 24th GIST MeetingDecember 14-16, 2005

  7. Number of Matches for Each DetectorWinter Campaigns 24th GIST MeetingDecember 14-16, 2005

  8. GERB SW Mean/CERES SW MeanWinter Campaigns 24th GIST MeetingDecember 14-16, 2005

  9. Number of Matches for Each DetectorSummer Campaigns 24th GIST MeetingDecember 14-16, 2005

  10. GERB SW Mean/CERES SW MeanSummer Campaigns 24th GIST MeetingDecember 14-16, 2005

  11. GERB SW Mean/CERES SW MeanAll Campaigns – GERB V001 24th GIST MeetingDecember 14-16, 2005

  12. GERB SW Mean/CERES SW MeanGERB V999 Campaigns 24th GIST MeetingDecember 14-16, 2005

  13. Criteria for SW Matches – Gridded-Based Comparison • Use GERB L1.5 NANRGs for time. • Use RMIB’s unfiltered SW radiances, angles, and geolocations for GERB. • Use CERES Edition 2 Revision 1 ES8s. • View zenith angles within 5° and relative azimuth angles within 1° (due to hardware GERB mode). • Grid boxes are 1° x 1°. Need at least 4 GERB points and at least 8 CERES points in a box. • Shows the mean difference between GERB and CERES radiances for each latitude bin. 24th GIST MeetingDecember 14-16, 2005

  14. GERB SW – CERES SWDecember 2003/January 2004 24th GIST MeetingDecember 14-16, 2005

  15. GERB SW – CERES SWDecember 2004/January 2005 24th GIST MeetingDecember 14-16, 2005

  16. GERB SW – CERES SWDecember 2004 w/ GERB V999 24th GIST MeetingDecember 14-16, 2005

  17. GERB SW – CERES SWJune/July 2004 24th GIST MeetingDecember 14-16, 2005

  18. GERB SW – CERES SWJune/July 2004 w/ GERB V999 24th GIST MeetingDecember 14-16, 2005

  19. GERB SW – CERES SWJune 2005 24th GIST MeetingDecember 14-16, 2005

  20. Criteria for LW Matches • Use GERB L2.0 ARGs for LW radiances & time • Use RMIB’s geolocations for GERB • Use CERES Edition 2 ES8s • View zenith angles within 5° • Now comparison is based on the row in the ARG array, not GERB detector number 24th GIST MeetingDecember 14-16, 2005

  21. Number of Matches for Each ARG RowWinter Campaigns 24th GIST MeetingDecember 14-16, 2005

  22. GERB LW Mean/CERES LW MeanWinter Campaigns 24th GIST MeetingDecember 14-16, 2005

  23. Number of Matches for Each ARG RowSummer Campaigns 24th GIST MeetingDecember 14-16, 2005

  24. GERB LW Mean/CERES LW MeanSummer Campaigns 24th GIST MeetingDecember 14-16, 2005

  25. Conclusions • CERES has been operated in 4 campaigns (2 NH winters & 2 NH summers) to measure radiances which are co-aligned with GERB . • CERES serves as a transfer radiometer in comparing the 256 GERB detectors. • Conclusions apply to detectors 49-174. For detectors 1-48 and 175-256, the sampling is insufficient. • GERB detectors vary by ±2% among themselves. • Between adjacent detectors for SW, there is a random uncorrelated change of ~½% and a long range structure (over a score or more) of ±2%. • This structure is seen in V999 also. 24th GIST MeetingDecember 14-16, 2005

  26. Conclusions (cont.) • Differences between SW radiances are consistent between both comparison methods. • For detector-based, GERB/CERES ratio is in range of 0.93 to 0.97 for V001 and 1.03 to 1.08 for V999. • For gridded-based, relative difference is in range of –5.2% to –6.2% for V001 and 4.7% to 5.7% for V999. • For LW radiances, GERB/CERES ratio is in range of 1.00 ± 0.01. • Comparisons are reproducible within ±1% among campaigns. 24th GIST MeetingDecember 14-16, 2005

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