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MODIS RGB. MODIS AOD. NAAPS “Natural”. Aerosol Data Assimilation Basics. MODAPS: L1b to MOD04_L2 MOD04_L2 to Assimilation-Ready AOD product. NAAPS = Navy Aerosol Analysis and Prediction System NAVDAS = Navy Variational Data Assimilation System Now operational at Navy. NAAPS + NAVDAS.
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MODIS RGB MODIS AOD NAAPS “Natural” Aerosol Data Assimilation Basics • MODAPS: L1b to MOD04_L2 • MOD04_L2 to Assimilation-Ready AOD product • NAAPS = Navy Aerosol Analysis and Prediction System • NAVDAS = Navy Variational Data Assimilation System • Now operational at Navy NAAPS + NAVDAS • J.L. Zhang et al., “A System for Operational Aerosol Optical Depth Data Assimilation over Global Oceans”, JGR 2008.
Example: AOD for Aerosol Data Assimilation • 6 hours of MODIS L2 aerosol product • ~72 files, ~1MB/file • ~200K retrievals • 10km resolution • 6 hours of AOD for Data Assimilation • 1 file, 150K • 2000-3000 data points • 1 degree resolution 2007110109-2007110115
Over Ocean Wind speed correction (uses NWP output) Microphysical correction Textural filtering Re-gridding Assignment of estimated uncertainty Over Land Albedo correction Snow filtering uses static 16-day climatology derived from 2001-2008 MOD43 snow/albedo Microphysical correction Textural filtering Re-gridding Assignment of estimated uncertainty Components of processing to make Assimilation-Ready AOD
Data Assimilation Produces Large Improvements in Aerosol Models • Cumulative Distribution of AOD Error vs AERONET from 5-year re-analysis • NO DATA ASSIMILATION OCEAN-ONLY DA OCEAN+LAND DA • “Gaps” between lines represent errors reduced • RMSE vs AERONET reduced 45% by MODIS AOD assimilation
