1. Line-by-Line Radiative Transfer Model (LBLRTM) Calculations for Gas Corrections for MODIS Falguni Patadia, Rob Levy November 8, 2012 Aerosol Retreat

2. DERIVING MODIS GAS CORRECTION COEFFICIENTS - (for water vapor) (Or ) ρ L1B λ = ρ m λ / T gas λ

3. MODIS GAS CORRECTION COEFFICIENTS LBLRTM BASED GAS CORRECTION COEFFICIENTS

4. Transmittance (120 km) Wavelength (nm) Transmittance (120 km) Water Vapor (cm) Transmittance (120 km) Ln(AirMass_Factor*WaterVapor) LBLRTM FOR MODIS CHANNEL 1 - ONLY H20 ; NO RAYLEIGH Water Vapor = 0.25 cm Water Vapor = 10 cm The Black Line Curve is the Relative Spectral Response Function for MODIS CH7 VZA = Ln(ln(1/Transmittance (120 km))) Ln(AirMass_Factor*WaterVapor)

5. Transmittance (120 km) Wavelength (nm) Transmittance (120 km) Water Vapor (cm) Transmittance (120 km) Ln(AirMass_Factor*WaterVapor) LBLRTM FOR MODIS CHANNEL 2 - ONLY H20 ; NO RAYLEIGH Water Vapor = 0.25 cm Water Vapor = 10 cm The Black Line Curve is the Relative Spectral Response Function for MODIS CH7 VZA = Ln(ln(1/Transmittance (120 km))) Ln(AirMass_Factor*WaterVapor)

6. Transmittance (120 km) Wavelength (nm) Transmittance (120 km) Water Vapor (cm) Transmittance (120 km) Ln(AirMass_Factor*WaterVapor) LBLRTM FOR MODIS CHANNEL 5 - ONLY H20 ; NO RAYLEIGH Water Vapor = 0.25 cm Water Vapor = 10 cm The Black Line Curve is the Relative Spectral Response Function for MODIS CH7 VZA = Ln(ln(1/Transmittance (120 km))) Ln(AirMass_Factor*WaterVapor)

7. Transmittance (120 km) Wavelength (nm) Transmittance (120 km) Water Vapor (cm) Transmittance (120 km) Ln(AirMass_Factor*WaterVapor) LBLRTM FOR MODIS CHANNEL 7 - ONLY H20 ; NO RAYLEIGH Water Vapor = 0.25 cm Water Vapor = 10 cm The Black Line Curve is the Relative Spectral Response Function for MODIS CH7 VZA = Ln(ln(1/Transmittance (120 km))) Ln(AirMass_Factor*WaterVapor)

8. To Do List for Gas Corrections: -Different atmospheres (US Standard, Mid-latitude etc) -LBLRTM for Ozone, CO 2 -Same exercise for VIIRS

10. Transmittance (120 km) Wavelength (nm) Transmittance (120 km) Water Vapor (cm) Transmittance (120 km) Ln(AirMass_Factor*WaterVapor) LBLRTM FOR MODIS CHANNEL 3 - ONLY H20 ; NO RAYLEIGH Water Vapor = 0.25 cm Water Vapor = 10 cm The Black Line Curve is the Relative Spectral Response Function for MODIS CH7

11. Transmittance (120 km) Wavelength (nm) Transmittance (120 km) Water Vapor (cm) Transmittance (120 km) Ln(AirMass_Factor*WaterVapor) LBLRTM FOR MODIS CHANNEL 4 - ONLY H20 ; NO RAYLEIGH Water Vapor = 0.25 cm Water Vapor = 10 cm The Black Line Curve is the Relative Spectral Response Function for MODIS CH7

12. Transmittance (120 km) Wavelength (nm) Transmittance (120 km) Water Vapor (cm) Transmittance (120 km) Ln(AirMass_Factor*WaterVapor) LBLRTM FOR MODIS CHANNEL 6 - ONLY H20 ; NO RAYLEIGH Water Vapor = 0.25 cm Water Vapor = 10 cm The Black Line Curve is the Relative Spectral Response Function for MODIS CH7