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Radiative Coupling in the Oceans using MODIS-Aqua Ocean Radiance Data Watson Gregg, Lars Nerger Cecile Rousseaux NASA/GMAO Assimilate MODIS-Aqua Water-Leaving.

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Presentation on theme: "Radiative Coupling in the Oceans using MODIS-Aqua Ocean Radiance Data Watson Gregg, Lars Nerger Cecile Rousseaux NASA/GMAO Assimilate MODIS-Aqua Water-Leaving."— Presentation transcript:

1 Radiative Coupling in the Oceans using MODIS-Aqua Ocean Radiance Data Watson Gregg, Lars Nerger Cecile Rousseaux NASA/GMAO Assimilate MODIS-Aqua Water-Leaving Radiances to: 1) Improve understanding of the propagation of light in the surface layer Primary Production Heat transfer -- Changes in ocean density structure and circulation 2) Invert the radiance assimilation into new information on model phytoplankton groups, CDOM, and other internal model variables.

2 Chlorophyll, Phytoplankton Groups Primary Production Nutrients DOC, DIC, pCO 2 Spectral Irradiance/Radiance Outputs: Radiative Model (OASIM) Circulation Model Winds SST Shortwave Radiation Layer Depths IOP, E u E d E s Sea Ice NASA Ocean Biogeochemical Model (NOBM) Winds, ozone, humidity, pressure, precip. water, clouds, aerosols Dust (Fe) Advection-diffusion Temperature, Layer Depths Biogeochemical Processes Model E d E s

3 Ozone Molecules, aerosols Oxygen Water vaporCO 2 air sea EdEd EsEs (1 -  ) EdEd EsEs EdEd EsEs EuEu  E d, E s LwNLwN Total Surface Irradiance (direct+diffuse; spectrally integrated; clear/cloudy): bias=1.6 W m -2 (0.8%) RMS=20.1 W m -2 (11%) r=0.89 (P<0.05) OASIM Surface Clear Sky Spectral Irradiance (PAR wavelengths): RMS=6.6% Integrated PAR: RMS=5.1%

4 mW cm -2 um -1 sr -1 Modeling Water-Leaving Radiances (with assimilated chlorophyll) Tropical Rivers (CDOM) Cocco- lithophores

5 ΔLw N = LwN assim - LwN model or

6 450 475500600625650675 a( λ ), b b ( λ ) 525550575700350375400425 Chlorophyll components: diatoms chlorophytes cyanobacteria coccolithophores CDOM water a w ( λ ), b bw ( λ ) a CDOM ( λ ) a p ( λ ), b bp ( λ ) OASIM Upwelling Irradiance (Forward Model) detritus a d ( λ ), b bd (λ) 443 488412550 667 MODIS-Aqua Upwelling Radiance (Inverse Model) Objective 2: Invert the radiance assimilation into new information on model phytoplankton groups, CDOM, and other internal model variables.

7 Consistent Ocean Chlorophyll from NPP/VIIRS NPP Science Team for Climate Data Records Watson W. Gregg and Nancy W. Casey Investigate the ability of an established approach to improve the consistency of VIIRS ocean color data. Utilizes completely processed and gridded ocean color data (Level-3 Environmental Data Records): 1)applies in situ data for a posteriori correction, and then 2)applies data assimilation to correct sampling problems.

8 In situ Data NODC NASAAMT ESRID Empirical Satellite Radiance-In situ Data Assimilated Data ESRID-Assimilated VIIRS Ocean Color Data Derive statistical relationships to reduce bias Global coupled numerical model Assimilate to reduce sampling biases Standard processing Satellite Data VIIRS EDRs ESRID Reduces bias in satellite observations, and sensor-to-sensor differences. Including those due to: Radiometric calibration Band locations and widths Band misregistration Out-of-band effects/crosstalk (mostly) Algorithms Orbit Gregg, et al., 2009, Remote Sensing of Environment

9 BiasUncertainty w/h = withholding of in situ data log bias and uncertainty in parentheses ESRID Empirical Satellite Radiance-In situ Data Algorithm

10 Global Annual Median Chlorophyll circa 2007 Processing ESRID improves consistency between disparate data sets Unifies the representation of ocean biology from ships and satellites Gregg and Casey, Geophysical Research Letters, 2010

11 North Indian Antarctic Equatorial Atlantic mg m -3 Sampling Differences/Biases

12 Aerosol optical thickness limit = 0.4 globally = 0.3 North/ Equatorial Indian = 0.3 North Central/ South Atlantic Data eliminated Equatorial Atlantic Two-Step Process to Remove Sampling Differences: 1) Remove high aerosol regions and tropical river regions (Equatorial Atlantic)

13 ESRID-Assimilated Global Annual Median Chlorophyll for MODIS-Aqua mg m -3 Global Annual Median Chlorophyll for MODIS-Aqua Step 2: Assimilate to backfill missing regions/seasons


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