1. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 MODIS Sea-Surface Temperatures Peter J Minnett & Robert H. Evans With Guillermo Podestà Kay Kilpatrick (retired), Sue Walsh, Vicki Halliwell, Liz Williams Rosenstiel School of Marine & Atmospheric Science University of Miami.

2. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 Outline Atmospheric correction algorithms – Current – Latitude-band coefficients – Triple-band algorithms ECV CDR Community demand

3. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 Standard SST Retrieval Equation SST = a + b*T 11 + c*(T 11 -T 12 )*T ref + d*(sec( θ ) -1)*(T 11 -T 12 ) – where θ is the zenith angle of the instrument – T 11 and T 12 are the brightness temperatures Bands 31 and 32 – Two set of monthly coefficients are determined for T 11 – T 12 ≤ T switch (temperate to polar) T 11 – T 12 > T switch (equatorial to temperate) Quality Levels – Four quality levels (0-3) where 0 indicates the highest confidence Current Challenges – Mid-high latitude seasonal anomalies, – Dust aerosols and high water vapor

4. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 Next Generation SST Improvements Reduce High Latitude Seasonal Oscillation Approach: – Estimate Coefficients using 20 o zonal bands centered at the Equator, ± 2.5 o transition between bands – Coefficients estimated monthly and repeat for each year for a given sensor (volcano periods to be handled separately) – Reference SST: Reynolds ¼ o, daily. Uses AMSR, Pathfinder SST and in situ observations retains SST in high gradient regions

5. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 Application of LATBAND to MODIS AQUA 11 μ m SST Median of SST residuals by quarter (2002-2008). Upper panel corresponds to latitude-specific SST residuals; lower panel is current SST residuals Note high latitude seasonal oscillations Latband implementation reduces seasonal residual oscillations

6. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 Application of LATBAND to MODIS AQUA 11 μ m SST Latband σ ~0.4 K Current algorithm σ ~ 0.5 K

7. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 MODIS AQUA 2 and 3 band (8.6, 11, 12μ) Night - Latband SST- Quality 1 2 Band 02 Jul 06 Difference Field Reynolds V2- MODIS Yellow-Red: MODIS Cold Use of Q0 data removes cold retrievals 3 Band 02 Jul 06 3K -3K 3K -3K

8. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 Histograms of MODIS AQUA SST residuals Vertical lines: 5, 25, 50, 75, 95 percentiles. From MODIS satellite-in situ match-up database. Residuals: Satellite - Buoy Reynolds V2 –Q0 residuals MODIS AQUA Night SST 02 Jul 06 3 band algorithm reduces cold retrievals Current SST residuals. Latband SST residuals

9. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 AQUA MODIS Statistics referenced to buoys Current Algorithm σ: SST ~.45-0.50SST4 ~ 0.38 – 0.40 Data SetMin Q1MedianMean Q3Max σ N Latitude SST Training-2.509-0.399-0.164-0.1780.0562.1140.38775011 Validation-2.285-0.403-0.170-0.1810.0552.3480.38940391 3-band SST Training-2.454-0.432-0.186-0.1820.0411.6460.36275011 Validation-2.688-0.403-0.181-0.1800.0441.7420.36340391 Latitude SST4 Training-2.218-0.356-0.177-0.208-0.0172.2370.34681906 Validation-2.123-0.358-0.177-0.208-0.0182.1760.34644104 3-band SST4 Training-2.577-0.330-0.198-0.211-0.0720.9030.24081906 Validation-2.516-0.329-0.198-0.211-0.0710.9270.24244104

10. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 Next Generation MODIS SST algorithm Reference SST field will be the V2 daily, 0.25 o Reynolds OI analysis that incorporates AMSR-E SST, AVHRR Pathfinder SST and In Situ SST observations. Use of this higher spatial and temporal resolution field enables retention of MODIS retrievals in high gradient regions. A 3-band algorithm permits more accurate retrievals in regions of high water vapor and dust aerosols. The 3-band algorithm significantly minimizes the presence of cold fringes around clouds. For MODIS the use of the 3-4 μ m bands extends the available retrievals in the presence of high water vapor and dust aerosols relative to the coverage provided by the 11-12 μ m bands.

11. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 SST: ECV & CDR 3 rd Miami IR Radiometry Workshop

12. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 L2P SSTs from the JPL PO-DAAC MODIS SSTs are the most requested L2P SST data sets. Data from Ed Armstrong

13. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 Conclusions New algorithm approaches (Latband) result in a significant reduction of uncertainty in IR satellite SST retrievals S.D. reduced from ~0.5K to <0.4K for 11 μ m retrievals, ~0.4K to < 0.35 K for 4 μ m retrievals Future implementation of 3 band algorithm suggests that cold fringes around clouds and aerosols can be detected and correction in these conditions is significantly improved, S.D. ~0.36 K for 11 μ m, ~0.24 K for 4 μ m. Generation of SST CDRs continues to be facilitated by NIST, using TXR to provide traceability to National temperate and radiometric standards. The community demand for MODIS SSTs is demonstrable.

14. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 Next steps Improved algorithms and coefficients delivered to NASA GSFC OBPG for V6 MODIS reprocessing. Use radiative transfer simulations to understand the physics of the improvements Assess contributions to error budgets of validating measurements; and provide NIST traceability. Apply lessons learned to VIIRS…..

15. International GHRSST User Symposium Santa Rosa, California, USA 28-29th May 2009 Acknowledgments Funding over many years from NASA MODIS Characterization Support Team (Jack Xiong) NASA Ocean Biology Processing Group Stimulating discussions and data from colleagues Sea-going colleagues…..