1. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 1 Prasanjit Dash 1,2, Alex Ignatov 1, Yuri Kihai 1,3, John Stroup 1,4, John Sapper 1, Boris Petrenko 1,3 1 NOAA NESDIS, NCWCP College Park, MD 2 Colorado State Univ, CIRA 3 GST, Inc, MD, USA 4 STG, Inc, VA, USA (Emails: FirstName.LastName@noaa.gov) The 15 th GHRSST 2014 meeting, ST-VAL Breakout session 2–6 Jun, 2014, Cape Town, South Africa Which VIIRS product to use? NOAA ACSPO vs. NAVO SEATEMP www.star.nesdis.noaa.gov/sod/sst/squam/HR/ SQUAM objective: A global, web-based, community, quasi NRT, monitor for SST producers & users ! AUS TAG and VIIRS breakout GHRSST XV, 2014 X Jun 2014, X:XX-X:XX AM

2. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 2 Major SST data providers: Projects and international group Acknowledgments Level-2 SST: VIIRS/AVHRR/MODIS -NESDIS SST Team : ACSPO (GAC: 5 platforms, FRAC: Metop-A & B, VIIRS: NPP, MODIS: Terra/Aqua) -D. May, B. McKenzie : NAVO SEATEMP -S. Jackson : IDPS (NPP) Level 4 SSTs: -M. Martin, J. R. Jones : OSTIA foundation, GHRSST Median Product Ensemble, OSTIA Reanalysis -B. Brasnett : Canadian Met. Centre, 0.2  foundation GHRSST support: Peter Minnett, Craig Donlon, Alexey Kaplan CMC

3. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 3 Outline 1. High-resolution (HR) SQUAM 2. Monitoring of VIIRS SSTs (ACSPO, IDPS, NAVO) in SQUAM Maps, Histograms, Time series, Dependence 3. Validation against QC’ed drifters 4. Persistent features in monthly maps 5. Closer look at ACSPO vs. NAVO: VZA dependence in Hovmöller space 6. Summary p: 4 p: 5-9 p: 10-11 p: 12-13 p: 14 p: 15 12 slides

4. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 4 Locate this website: Google: “SST + SQUAM + HR” The SST Quality Monitor (SQUAM), JTech, 27, 1899-1917, 2010 1. VIIRS SSTs in High-Res (HR) SQUAM

5. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 5 MapsHistogramsTime-seriesDependenciesHovmöller Night: VIIRS (IDPS) minus CMC L4, 15-May-2014 Initial product developed by private contractor, now discontinued and replaced by ACSPO Coverage is good but many cold spots indicate residual cloud/aerosol leakages 2. VIIRS SST in SQUAM: IDPS

6. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 6 MapsHistogramsTime-seriesDependenciesHovmöller Night: VIIRS (ACSPO) minus CMC L4, 15-May-2014 ACSPO is NOAA heritage SST product, now operational and replaced the IDPS Residual Cloud/Aerosol leakages reduced compared to IDPS 2. VIIRS SST in SQUAM: ACSPO

7. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 7 MapsHistogramsTime-seriesDependenciesHovmöller Night: VIIRS (NAVO) minus CMC L4, 15-May-2014 Reduced coverage (VZA<54°; 2×2 pixel processing; more conservative mask) Fewer leakages especially in the Tropics (on this particular day) 2. VIIRS SST in SQUAM: NAVO

8. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 8 MapsHistogramsTime-seriesDependenciesHovmöller ACSPO VIIRS – CMC NAVO VIIRS – CMC IDPS VIIRS – CMC 2. VIIRS SSTs in SQUAM: Example 15 May 2014, Night IDPS vs. ACSPO o Retrieval domain: Comparable o SST performance statistics: ACSPO superior NAVO vs. ACSPO o Retrieval domain: NAVO factor of ×2.6 smaller o SST performance statistics: Comparable

9. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 9 MapsHistogramsTime-seriesDependenciesHovmöller 2. Monitoring in SQUAM: VIIRS SSTs, Day o Mean and Std Dev of residuals (Sat SST – OSTIA) closely track each other o Similar observations for other references o NAVO: # of NAVO observations ~1/3 of ACSPO Day: very similar (this figure); Night: NAVO slightly but consistently better (see SQUAM-HR webpage) (for other products: see SQUAM-HR webpage) Monthly in situ val ---  NEXT SLIDE

10. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 10 o Mean and Std Dev of residuals (Sat SST – Drifters) closely track each other o Similar observations for other references o NAVO: # of NAVO observations ~1/3 of ACSPO Std Dev: NAVO slightly but consistently better MapsHistogramsTime-seriesDependenciesHovmöller 2. Validation: VIIRS SSTs (monthly, vs. drifters, Day)

11. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 11 3. NAVO/ACSPO Summary Statistics Products# of matches (%ACSPO)Min / Max (◦C) Mean / MedianStd Dev / RSDSkew / Kurt ACSPO NPP42,917 (night) 42,586 (day) -2.61 / 5.92 -2.82 / 4.12 -0.03 / 0.04 0.06 / 0.06 0.39 / 0.25 0.42 / 0.33 2.77 / 35.04 0.35 / 4.46 NAVO NPP12,912 (30.08%) 10,063 (23.62%) -2.58 / 2.20 -1.80 / 4.31 0.06 / 0.09 0.05 / 0.03 0.29 / 0.22 0.38 / 0.32 -0.97 / 7.51 0.58 / 5.89 IDPS NPP48,638 (113.33%) 46,208 (108.50%) -6.62 / 2.83 -8.04 / 6.43 -0.06 / 0.00 -0.07 / 0.02 0.42 / 0.26 0.65 / 0.42 -2.00 / 15.51 -1.68 / 11.23 * QC’ed drifters from iQuam: www.star.nesdis.noaa.gov/sod/sst/iquam/www.star.nesdis.noaa.gov/sod/sst/iquam/ Products# of matches (%ACSPO)Min / Max (◦C) Mean / MedianStd Dev / RSDSkew / Kurt ACSPO NPP117.10 million (night) 110.90 million (day) -4.52 / 9.35 -5.69 / 8.79 0.05 / 0.05 0.24 / 0.16 0.39 / 0.30 0.61 / 0.41 0.54 / 8.51 1.95 / 11.25 NAVO NPP45.29 mi (38.68%) 36.13 mi (32.58%) -8.12 / 5.55 -7.85 / 7.67 0.08 / 0.11 0.18 / 0.13 0.38 / 0.29 0.54 / 0.41 -0.92 / 7.61 0.67 / 8.14 IDPS NPP120.13 (102.58%) 111.96 (100.95%) -13.40 / 17.57 -27.40 / 13.96 0.01 / 0.04 0.17 / 0.21 0.47 / 0.32 0.79 / 0.45 -1.05 / 15.41 -0.56 / 10.11 Validation wrt. drifters, Feb 2014 Monitoring wrt. CMC, 15 May 2014

12. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 12 MapsHistogramsTime-seriesDependenciesHovmöller Day: VIIRS (ACSPO) minus CMC L4, Apr-2014 4. Looking for persistent features: Monthly aggregation Negative residuals in monthly maps suggest persistent cloud/aerosol leakages Positive residuals: Daytime diurnal warming? or NLSST algorithm artifacts?

13. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 13 MapsHistogramsTime-seriesDependenciesHovmöller Day: VIIRS (NAVO) minus CMC L4, Apr-2014 Some areas of the ocean are not covered even at monthly time interval Warm spots more pronounced: Differences in NAVO./ACSPO cloud screening? or SST algorithm? 4. Looking for persistent features: Monthly aggregation

14. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 14 5. VAL Statistics as a Function of Scan Angle ACSPO makes retrievals in full swath whereas NAVO at VZA<54° only Within the limited VZA domain, ACSPO and NAVO Std Dev values are close ACSPO STD Dev degrade towards swath edges Degradation is more complex than merely a function of VZA, and shows some seasonality

15. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 15  There are 2 global VIIRS products: NOAA ACSPO and NAVO SEATEMP. Both are archived at PO.DAAC / NODC in GDS2 format  IDPS product is being discontinued, due to suboptimal performance & lack of users. It is currently archived at CLASS in hdf5 and will be wiped off once complete record of ACSPO VIIRS from Jan 2012-on is archived  Relative merits of ACSPO and NAVO VIIRS SSTs o NAVO global coverage is about 1/3 of ACSPO. As a result, some areas of the ocean remain uncovered by the NAVO product for extended periods up to a month o Measured in their corresponding full retrieval domains, NAVO outperforms ACSPO, by a narrow (day) to moderate (night) margin. o However, in the “intersection” domain, both products show comparable performances THANK YOU! 6. Summary

16. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 16 Backup slides

17. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 17 MapsHistogramsTime-seriesDependenciesHovmöller 2. Monitoring in SQUAM: VIIRS SSTs, Night o Mean and Std Dev of residuals (Sat SST – OSTIA) closely track each other o Similar observations for other references o NAVO: # of NAVO observations ~1/3 of ACSPO slightly but consistently better (for other products: see SQUAM-HR webpage) Monthly in situ val ---  NEXT SLIDE

18. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 18 MapsHistogramsTime-seriesDependenciesHovmöller 2. Validation: VIIRS SSTs (monthly, vs. drifters, Night) o Mean and Std Dev of residuals (Sat SST – OSTIA) closely track each other o Similar observations for other references o NAVO: # of NAVO observations ~1/3 of ACSPO slightly but consistently better

19. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 19 MapsHistogramsTime-seriesDependenciesHovmöller 2. Monitoring in SQUAM: VIIRS SSTs, Day o Mean and Std Dev of residuals (Sat SST – OSTIA) closely track each other o Similar observations for other references o NAVO: # of NAVO observations ~1/3 of ACSPO Day: very similar (this figure); Night: NAVO slightly but consistently better (for other products: see SQUAM-HR webpage) Monthly in situ val ---  NEXT SLIDE

20. Which VIIRS product to use: ACSPO vs. NAVO GHRSST-XV, 2-6 June 2014, Cape Town, South Africa 20 o Mean and Std Dev of residuals (Sat SST – Drifters) closely track each other o Similar observations for other references o NAVO: # of NAVO observations ~1/3 of ACSPO Std Dev: NAVO slightly but consistently better MapsHistogramsTime-seriesDependenciesHovmöller 2. Validation: VIIRS SSTs (monthly, vs. drifters, Day)