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VIIRS Product Evaluation at the Ocean PEATE Frederick S. Patt Gene C. Feldman

VIIRS Product Evaluation at the Ocean PEATE Frederick S. Patt Gene C. Feldman. IGARSS 2010 July 27, 2010. Introduction. The NPP Mission will support the continuation of climate records generated from NASA sensors and missions.

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VIIRS Product Evaluation at the Ocean PEATE Frederick S. Patt Gene C. Feldman

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  1. VIIRS Product Evaluation at the Ocean PEATEFrederick S. PattGene C. Feldman IGARSS 2010 July 27, 2010

  2. Introduction • The NPP Mission will support the continuation of climate records generated from NASA sensors and missions. • The VIIRS instrument will generate (among with many other products) the Ocean Color and Chlorophyll (OCC) and Sea Surface Temperature (SST) Environmental Data Records (EDRs). • The NASA Science Teams will perform evaluation of the NPP data products generated by the Interface Data Processing Segment (IDPS) and recommend improvements to the algorithms. VIIRS Product Evaluation at the Ocean PEATE

  3. SDS and the PEATEs • The NASA Science Data Segment (SDS) is a distributed facility that will support the product evaluation activities of the Science Teams. • The Product Evaluation and Analysis Tool Elements (PEATEs) support data acquisition and archive, data processing, tool development and algorithm testing for the Science Teams. • The Ocean PEATE is supported within the Ocean Biology Processing Group (OBPG) at NASA Goddard Space Flight Center (GSFC), using the existing Ocean Data Processing System (ODPS). VIIRS Product Evaluation at the Ocean PEATE

  4. Product Evaluation Strategies • Comparisons between the VIIRS Ocean EDRs and current OBPG products will be performed in stages, in order to isolate the causes of differences. • The primary source of “truth” products will be the MODIS instrument on the Aqua satellite. VIIRS Product Evaluation at the Ocean PEATE

  5. VIIRS EDR Evaluation – Step 1 VIIRS EDR MODIS Level-2 COMPARE If SAME = OK If Different L1B (SDR) or Level-2 (EDR) Processing Problem VIIRS Product Evaluation at the Ocean PEATE

  6. VIIRS EDR Evaluation – Step 2 VIIRS EDR MODIS Level-2 Bin to Global Grid VIIRS Level-3 MODIS Level-3 COMPARE If SAME = OK If Different L1B (SDR) or Level-2 (EDR) Processing Problem

  7. VIIRS EDR Evaluation – Step 3 VIIRS SDR MODIS Level-1b L2Gen VIIRS Level-2 MODIS Level-2 COMPARE EDR Processing Problem If SAME = If Different VIIRS L1B (SDR) Processing Problem VIIRS Product Evaluation at the Ocean PEATE

  8. Evaluation Vs. Product Level • Level-1 (SDR) Evaluations • Onboard calibration analyses • Vicarious calibration • Level-2 (EDR) Evaluations • Matchup analyses • Residual detector (striping) and scan (RVS) dependence • Level-3 Product Evaluations • Sensor cross-comparisons • Algorithm comparisons • Temporal anomaly evaluations VIIRS Product Evaluation at the Ocean PEATE

  9. Onboard Calibration Analyses • NICSE has primary responsibility for radiometric calibration of VIIRS. • The VIIRS Ocean Science Team will provide supplemental analyses of onboard calibrator (solar diffuser and lunar) data to achieve radiometric accuracy needed for Ocean products. • Temporal radiometric stability has been achieved for SeaWiFS over the nearly 10 year mission using lunar calibrations. VIIRS Product Evaluation at the Ocean PEATE

  10. Vicarious Calibration • Vicarious calibration using surface measurements (e.g., MOBY) gives constant gain correction to TOA radiances over the mission • Analyses of calibration results provide insight into temporal and geometric sources of variation. VIIRS Product Evaluation at the Ocean PEATE

  11. Matchup Analysis • Ocean data granules in ODPS catalog are automatically matched with in situ data • SeaWiFS Bio-optical Archive and Storage System (SeaBASS) stores and manages in situ holdings from field programs and supported investigators. • Ocean staff acquire, QC and analyze new data samples. • Over 60,000 in situ profiles stored covering SeaWiFS/ MODIS time frame. VIIRS Product Evaluation at the Ocean PEATE

  12. Matchup Process Flow Chart VIIRS Product Evaluation at the Ocean PEATE

  13. Residual Detector Dependence • Level-3 multi-day products (same or different sensor) are resampled to generate values at Level-2 resolution. • Comparisons are performed by detector and mirror side to evaluate residual detector response errors VIIRS Product Evaluation at the Ocean PEATE

  14. Residual Scan Dependence • Level-3 multi-day products (same or different sensor) are resampled to generate values at Level-2 resolution. • Comparisons are performed by pixel number and mirror side to evaluate residual RVS errors VIIRS Product Evaluation at the Ocean PEATE

  15. Level-3 Product Generation • Sensor cross-comparisons and interannual comparisons require Level-3 binned (equal-area) products. • The Ocean PEATE has implemented software to process VIIRS EDRs to Level 3 binned products in current OBPG (SeaWiFS-like) format. • This will automatically provide the additional capabilities to produce multi-temporal composites, standard mapped image (SMI) products and Level-3 browse files. VIIRS Product Evaluation at the Ocean PEATE

  16. Sensor/Algorithm Cross-Comparisons • Level-3 parameters (e.g., nLw) compared for common spectral bands • Common bins extracted and compared over the period of overlap between the sensors • Comparisons are performed globally (deep water, oligotrophic, mesotrophic, eutrophic), zonally and for specified regions. VIIRS Product Evaluation at the Ocean PEATE

  17. Zonal Cross-Comparisons VIIRS Product Evaluation at the Ocean PEATE

  18. Chlorophyll Image Comparisons SeaWiFS Deep-Water Chlorophyll 2002 193 MODIS Deep-Water Chlorophyll 2002 193 SeaWiFS Deep-Water Chlorophyll 2006 365 MODIS Deep-Water Chlorophyll 2006 365 VIIRS Product Evaluation at the Ocean PEATE

  19. Temporal Anomaly Evaluations • Level-3 global averages for the entire mission are fit to a periodic function to remove natural annual variability. • The differences between the global averages and the annual cycle are then plotted over the mission. • The results show both geophysical variations and any unexpected changes due to uncharacterized instrument effects or algorithm artifacts. VIIRS Product Evaluation at the Ocean PEATE

  20. Temporal Anomaly Example VIIRS Product Evaluation at the Ocean PEATE

  21. Conclusion • The Ocean PEATE will be supported using the proven capabilities of the ODPS, which will support EDR evaluation strategies successfully employed on current missions. • Our approach provides progressive stages of evaluation for Level-1B (SDR), Level-2 (EDR) and Level-3 products. • Evaluation methodologies and tools are already established for data sets cataloged within the ODPS. • The hierarchy of methods will provide for rigorous evaluation of the VIIRS Ocean products. VIIRS Product Evaluation at the Ocean PEATE

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