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JPSS SST Team Telecon 11 April 2012

JPSS SST Team Telecon 11 April 2012. Analyses of IDPS NPP SST Quality Flags using 1 day of global data in SQUAM 20 March 2012 Prasanjit Dash, Sasha Ignatov with discussions and contributions from Yury Kihai, John Stroup, Boris Petrenko. All data presented here are available online at

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JPSS SST Team Telecon 11 April 2012

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  1. JPSS SST Team Telecon11 April 2012 Analyses of IDPS NPP SST Quality Flags using 1 day of global data in SQUAM 20 March 2012 Prasanjit Dash, Sasha Ignatov with discussions and contributions from Yury Kihai, John Stroup, Boris Petrenko All data presented here are available online at http://www.star.nesdis.noaa.gov/sod/sst/squam/HR/index_v2.html Go to Maps or Histograms on top select 2012 – 03 – 20 at the bottom Play with “#1 .. #7”; “Night-Day”; “Product”; and “Reference SST” buttons

  2. Objectives of this analysis • IDPS SST product analyses and presentation • Providing feedback to VCM Team • Adding IDPS SST in SQUAM Monitoring • Validation against in situ • Recalculation of SST coefficients • Advising users on SST product use • …. • These & many other tasks require settling on SST domain (i.e., defining Cloud Flags and SST Quality Flags)

  3. IDPS SST EDR Quality Flags tested in SQUAM • 10 QFs (Byte Arrays) available in IDPS files • 4 in VSSTO files (QF1-QF4) • 6 in IICMO files (QF5-QF10) • Some of IICMO QFs are reused in VSSTO (should check for consistency?) • Various combinations of the following QFs are considered SST QFs: - “High Quality” - “Degraded” CFs: - “Confidently Clear” - “Probably Clear” Additional QFs: - Adjacency test (8 adjacent pixels are “Confidently Clear”) - AOT<0.6 - Thin Cirrus test NB. All pixels with fill-values are excluded; only valid range kept

  4. Seven IDPS QF combinations tested in SQUAM • 1: ‘High Quality’ • 2: ‘High Quality OR Degraded’ • 3: ‘High Quality OR Degraded’ AND ‘Confidently OR Probably clear’ • 4: ‘High Quality OR Degraded’ AND ‘Confidently clear’ • 5: #4 AND 'adjacent cloud test (confidently clear adjacent pixels)’ • 6: #4 AND 'Remove pixels with AOT@550nm > 0.6' • 7: #4 AND 'Remove pixels detected with thin cirrus‘ • ACSPO VIIRS SST is shown first • (1 combination: clear sky) • followed by 7 combinations for IDPS

  5. Nighttime Maps

  6. ACSPO minus OSTIA Note residual Cloud/Aerosol(?) leakages in the Tropics

  7. IDPS minus OSTIA: #1: ‘High Quality’ Few Cloud leakages but Swath Truncated

  8. IDPS minus OSTIA: #2: ‘High Quality OR Degraded’ More Cloud leakages (including outside Tropics); and Limb Darkening/Cooling

  9. IDPS minus OSTIA: #3: ‘High Quality OR Degraded’ AND ‘Confidently OR Probably clear’ Cloud leakages and Limb Cooling reduced but still significant

  10. IDPS minus OSTIA: #4: ‘High Quality OR Degraded’ AND ‘Confidently clear’ Cloud leakages and Limb cooling reduced - Compares best with ACSPO for night time NB: HQ and D should be both Conf Clear?

  11. IDPS minus OSTIA: #5: ‘#4’ AND ‘Adjacent cloud: confidently clear’ Cloud leakages reduced but coverage reduced significantly - many good pixels are gone

  12. IDPS minus OSTIA: #6: ‘#4’ AND ‘Remove pixels with AOT@550nm > 0.6’ Little effect on leakages and coverage

  13. IDPS minus OSTIA: #7: ‘#4’ AND ‘Remove pixels detected thin cirrus’ Has some effect but removes good pixels

  14. Nighttime Histograms

  15. ACSPO minus OSTIA Close to a Gaussian shape & Narrow

  16. IDPS minus OSTIA: #1: ‘High Quality’ Fewer Cloud leakages but Swath Truncated

  17. IDPS minus OSTIA: #2: ‘High Quality OR Degraded’ More Skewed & Wider

  18. IDPS minus OSTIA: #3: ‘High Quality OR Degraded’ AND ‘Confidently OR Probably clear’

  19. IDPS minus OSTIA: #4: ‘High Quality OR Degraded’ AND ‘Confidently clear’ Per documentation and version of IDPS SST code we have, “HQ” or “D” SSTs must all be confidently clear – this is not the case

  20. IDPS minus OSTIA: #5: ‘#4’ AND ‘Adjacent cloud: confidently clear’ “slimmer” in central part but heavier tail; dramatically fewer NOBS

  21. IDPS minus OSTIA: #6: ‘#4’ AND ‘Remove pixels with AOT > 0.6@550nm’ Little effect on leakages and coverage

  22. IDPS minus OSTIA: #7: ‘#4’ AND ‘Remove pixels detected thin cirrus’ Little effect on leakages and coverage

  23. 20 March 2012 – Global Night Summary ΔT = “VIIRS minus OSTIA” SST (expected ~0) Recommend use combination #4 “High Quality” “Degraded” and “Confidently Clear” (no additional Adjacency screening) – 17% smaller domain, degraded performance statistics

  24. Daytime Maps

  25. ACSPO minus OSTIA Cloud/Aerosol (?) leakages in the Tropics; Some positive anomalies expected, due to diurnal warming

  26. IDPS minus OSTIA: #1: ‘High Quality’ Some Cloud leakages; Truncated Swath

  27. IDPS minus OSTIA: #2: ‘High Quality OR Degraded’ Significant Cloud leakages and Limb Cooling

  28. IDPS minus OSTIA: #3: ‘High Quality OR Degraded’ AND ‘Confidently OR Probably clear’ Cloud leakages & Limb Cooling somewhat reduced but still significant

  29. IDPS minus OSTIA: #4: ‘High Quality OR Degraded’ AND ‘Confidently clear’ Cloud leakages and Limb cooling reduced - Compares best with ACSPO NB: HQ and D should be both Conf Clear?

  30. IDPS minus OSTIA: #5: ‘#4’ AND ‘Adjacent cloud: confidently clear’ Fewer Cloud leakages; Smaller Coverage

  31. IDPS minus OSTIA: #6: ‘#4’ AND ‘Remove pixels with AOT > 0.6@550nm’ Small effect on leakages and Coverage

  32. IDPS minus OSTIA: #7: ‘#4’ AND ‘Remove pixels detected thin cirrus’ Small effect on leakages and Coverage

  33. Daytime Histograms

  34. ACSPO minus OSTIA Close to a Gaussian shape; Narrow

  35. IDPS minus OSTIA: #1: ‘High Quality’ Wider; Skewed; Much fewer NOBS

  36. IDPS minus OSTIA: #2: ‘High Quality OR Degraded’ Wider; Much Larger NOBS

  37. IDPS minus OSTIA: #3: ‘High Quality OR Degraded’ AND ‘Confidently OR Probably clear’ About same as #2

  38. IDPS minus OSTIA: #4: ‘High Quality OR Degraded’ AND ‘Confidently clear’ As close to ACSPO as one can get with QFs NB: HQ and D should be both Conf Clear?

  39. IDPS minus OSTIA: #5: ‘#4’ AND ‘Adjacent cloud: confidently clear’ Significantly smaller domain; However, Some improvements in statistics

  40. IDPS minus OSTIA: #6: ‘#4’ AND ‘Remove pixels with AOT > 0.6@550nm’ Small effect on leakages and Coverage

  41. IDPS minus OSTIA: #7: ‘#4’ AND ‘Remove pixels detected thin cirrus’ Small effect on leakages and Coverage

  42. 20 March 2012 – Global Day Summary ΔT = VIIRS minus OSTIA SST (expected ~0) Recommend use a combination of “High” & “Degraded” (no additional screening) – 10% larger domain compared to ACSPO, significantly degraded performance statistics

  43. Observations and Suggested Initial Selection of QFs - 1 • Sensitivity of IDPS SST to selection of QFs, and comparisons with ACSPO were performed for one full day of global data - 20 March 2012 • IDPS SST retrieval domain and performance statistics is closest to ACSPO for the following combination of QFs: • “High Quality or Degraded” and “Confidently Clear” • We plan to use this combination for all IDPS analyses – Team agrees? • Will continue working with VCM Team to ensure that this domain, and SST performance in it, are comparable to ACSPO’s • Currently • Night • VCM more conservative than ACSPO  17% less SST retrievals • In this smaller domain, VCM still shows more leakages than ACSPO • Daytime • VCM more liberal than ACSPO  10% more SST retrievals • In this larger domain, much more cloud leakages than in ACSPO

  44. Observations and Suggested Initial Selection of QFs - 2 • After settling on SST domain, need to recalculate SST coefficients. Current coefficients show significant Limb cooling during both day and night • According to the documentation and version of IDPS code available at STAR: Both “High Quality” and “Degraded” must only be set for “Confidently Clear”. Our analyses show this is not the case • Using only “high quality pixels” truncates swath & significantly reduces data volume, with disproportionately small improvement in SST statistics • Requirement that all 8 adjacent pixels are all confidently clear, results in significant good data loss, with marginal improvement in SST statistics • AOT and thin cirrus flags do not statistically significantly affect the global retrieval domain & SST statistics in it • The thin cirrus domain appears suspiciously correlated with AOT condition – checking on that • AOT and thin cirrus flags do not statistically significantly affect the global retrieval domain & SST statistics

  45. Back-Up Slides • B. Petrenko recommendations from 3/28/2012 Telecon

  46. Preliminary recommendation from individual images analyses (SST Telecon 2012/03/28, B. Petrenko) As the 1st step, we suggest to preliminary validate SST EDR with the following conditions: a combination of “0.4K” and “0.7K” uncertainty (see slide 5) but without limitation on Sat Zen Angle (ACSPO uses full scan): AOT < 0.6; and VCM indicated “Confidently Clear” for that horizontal cell; and VCM indicated “Confidently Clear” for the 8 adjacent cells; and VCM does not indicate Thin Cirrus clouds for that cell; and Retrieved SST < 305K

  47. Conditions under which SST Performance (Uncertainty?) Requirements should be met (Ref: 474-00012 JPSS EDR Production Report for NPP) QF=“High Quality” (+ Condition for adjacent pixels ?) 0.4K Performance Requirements: AOT < 0.6; and VCM indicated “Confidently Clear” for that horizontal cell; and VCM indicated “Confidently Clear” for the 8 adjacent cells; and VCM does not indicate Thin Cirrus clouds for that cell; and Retrieved SST < 305K; and VIIRS Sat Zen Angle < 40°. 0.7K Performance Requirements: Same as above but for 40°<= Sat Zen Angle <53° range

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