1 / 28

Sea-Surface Temperature from Suomi-NPP VIIRS: Algorithm Development and Uncertainty Estimation

Sea-Surface Temperature from Suomi-NPP VIIRS: Algorithm Development and Uncertainty Estimation Peter J. Minnett, Robert H. Evans, Guillermo P. Podestá , Katherine A. Kilpatrick Rosenstiel School of Marine and Atmospheric Science, University of Miami. Outline.

kedma
Download Presentation

Sea-Surface Temperature from Suomi-NPP VIIRS: Algorithm Development and Uncertainty Estimation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Sea-Surface Temperature from Suomi-NPP VIIRS: Algorithm Development and Uncertainty Estimation Peter J. Minnett, Robert H. Evans, Guillermo P. Podestá, Katherine A. Kilpatrick Rosenstiel School of Marine and Atmospheric Science, University of Miami SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  2. Outline Focus on possible contribution to the SST Climate Data Record. Overview of VIIRS characteristics relevant for SST retrievals Form of the atmospheric correction algorithms. Uncertainties: • comparisons vs drifting buoys. • comparisons vs ship radiometers. Future directions. SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  3. Introduction VIIRS is the first of a new class of satellite radiometer, using design elements from MODIS and SeaWiFS. At least two more VIIRS will be flown on the NOAA JPSS satellites replacing the AVHRRs on the NOAA-n polar orbiters. The European radiometer to replace the AVHRRs on MetOp-A and MetOp-B, called METimage, will have a similar optical design, but will have SST channels more similar to MODIS. SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  4. Suomi NPP • Launched on 28 October, 2011. • Equator crossing - 1:30 p.m. • Altitude of 824 km. • 16-day repeat cycle • Five key instruments: • Advanced Technology Microwave Sounder (ATMS) • Cross-track Infrared Sounder (CrIS) • Ozone Mapping and Profiler Suite (OMPS) • Clouds and the Earth's Radiant Energy System (CERES) • Visible Infrared Imaging Radiometer Suite (VIIRS) Photo courtesy Ball Aerospace. SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  5. VIIRS • Rotating telescope with “Half-Angle Mirror” fore-optics. • Spectral Bands: – Visible/ Near IR: 9 plus Day/Night Band – Mid-Wave IR: 8 – Long-Wave IR: 4 • Imaging Optics: 18.4 cm Aperture. • 114 cm Focal Length. • Scan Range of earth view: ±56º from nadir. • Swath width: 3000 km. SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  6. VIIRS Components SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  7. VIIRS spectral bands SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  8. VIIRS SST RSRs Green - MODIS Red -VIIRS Purple lines are the VIIRS broad-band imaging bands with nadir resolution of 0.375km. Moeller, C., et al. VIIRS F1 "best" relative spectral response characterization by the government team. in SPIE 8153, 2011. SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  9. VIIRS pixel aggregation HSI: Horizontal Sampling Interval Schueler, C. F., Lee, T. F. and Miller, S. D., "VIIRS constant spatial-resolution advantages". International Journal of Remote Sensing, 34(16): 5761-5777 (2013). SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  10. VIIRS vs MODIS spatial resolution From http://www.ipo.noaa.gov/ams/2010/posters/AGU_AMS-RAY_NGAS-VIIRSHeritageSystems-SNODGRASS_GUENTHER_ANDREAS-WE_PRINT-PR.pdf

  11. SST retrieval • Cloud screening – required to identify all pixels with contamination by cloud (or aerosols) • Atmospheric correction – required to correct for the effect of the intervening atmosphere

  12. Miami decision-tree cloud mask

  13. Effect of the atmosphere Temperature deficit VIIRS M15 (λ=10.76µm) Temperature deficit VIIRS M16 (λ=12.01µm)

  14. VIIRS Atmospheric Correction Algorithms Miami V6: • SST2b = a0 + a1T11 + a2(T11 – T12) Tsfc + a3(T11-T12)Sq • SST3b = a0 + a1T11 + a2(T3.7 – T12) Tsfc + a3Sq Miami V7: • SST2b = a0 + a1T11+ a2(T11– T12) Tsfc+ a3(T11-T12)Sq+ a4Sq+ a5Sqχ χ = fn(lat) • SST3b = a0 + a1T11+ a2(T3.7– T12) Tsfc+ a3Sq+ a4Sqχ χ = 0.1 for |lat| ≤ 40°; 2.0 for |lat| > 40° Sq= sec(θ)-1 SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  15. SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  16. Spatial distribution of errors Comparisons with buoys SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  17. Simple Global Statistics Statistics of the differences between the VIIRS skin SST retrievals and the subsurface temperatures measured from drifting buoys. SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  18. Zenith angle dependence SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  19. Spatial comparisons – WindSat SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  20. Time dependences SST 2b day SST 2b night SST 3b night Comparisons to buoy temperatures SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  21. Time dependences – in latitude bands Comparisons to buoy temperatures SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  22. Ship radiometers: M-AERIs M-AERIs, new and old, on R/V Knorr. Transit from Woods Hole to Cape Town, and an Agulhas mooring recovery cruise. Mean 0.024K, stdev = 0.201K, n = 78 VIIRS v7.0 algorithm Reference SST WindSat 5day average. Skin SST measurements from R/V Knorr. January – March 2013. M-AERIs are Fourier Transform Infrared interferometers with two internal blackbody calibration targets. Pre- & post-deployment lab calibration against NIST-traceable calibrators. SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  23. Ship radiometers: ISARs M/V Andromeda Leader M/V Horizon Spirit Mean -0.058 K, stdev = 0.417K, n = 337 ISARs are autonomous filter radiometers with two internal blackbody calibration targets. Pre- & post-deployment lab calibration against NIST-traceable calibrators. Data relayed in real-time by Iridium. SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  24. Spatial distribution of errors - radiometers Comparisons with ship radiometers SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  25. Summary • VIIRS is a good SST radiometer. • Errors are pleasingly stable in time. • Spatial comparisons with WindSat microwave SSTs give more uniform agreement than with infrared OI SSTs. • Full swath retrievals are improved by the use of additional zenith angle terms. • Form of algorithms provides continuity with heritage sensors. • Comparison with ship-board radiometers provides mechanism for contributing the SST Climate Data Record. SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  26. Future directions • Continue to populate matchup data base, leading to error hypercube. • Continue refinement of atmospheric correction algorithm. • Compare with AMSR2 microwave SSTs. • Continue matchups with ship radiometers – provide pathway to contributing to the SST CDR. • Continue to work with NOAA STAR VIIRS Team. SPIE Ocean Sensing and Monitoring. Baltimore, May 6, 2014

  27. Acknowledgements Funding from NASA and NOAA JPSS Thank you.

More Related