Calculating AODs from MODIS radiancesCalculating AODs from MODIS radiances

Easan DruryEasan DruryG4 - w/ Jacob group @ HarvardG4 - w/ Jacob group @ Harvard

July 22, 2004July 3, 2004

Inferring AODs from MODIS radiances ( and using MODIS radiances as the observational variable for constraining modeled aerosols )

αMOLECULAR αAEROSOLαSURFACE

Molecular scattering & absorbing

Aerosol scattering & absorbing

Surface reflectance

2nd assumption 1st assumptionWhat we want!

αMOLECULAR αSURFACEαAEROSOL

MODIS (visible) (visible/IR) MODIS (IR)

1 aerosol molecular

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T

Inferring Surface AlbedoInferring Surface Albedo

Visible to IR reflectances:

• Top of the atmosphere reflectance for the 1x1.25 degree bin.

• Regress the bottom quartile of visible to IR reflectance.

Reflectance ratios during July-August, 2004:

GEOS-Chem optical propertiesGEOS-Chem optical properties

MODIS & AERONET AODs

AERONET - MODIS AODs

Fraction of Pixels used

Difference in 10x10km2 MODIS and AERONET AODs