Satellite Determinations of the Relationship between Total Longwave Radiation Flux and Infrared Window Radiance

Abstract
Nimbus-7 satellite observations are used to determine the relationship between the total longwave radiation flux and the radiance in the 10-12 μm infrared window. The total longwave fluxes are obtained from the earth radiation budget (ERB) narrow-field-of-view (NFOV) observations of total radiance; the IR window radiances are those measured by the Temperature Humidity Infrared Radiometer (THIR). Regression equations are obtained relating the total flux equivalent brightness temperatures to the radiance equivalent brightness temperature of the IR window. These empirical equations are compared to similar regression equations based on radiative transfer calculations for a large sample of atmospheric soundings. The latter theoretical equations are used by NOAA in the processing of IR window observations from operational polar orbiting satellites to obtain total longwave flux estimates. The observational results indicate that there is a very high correlation between the flux equivalent brightness temp... Abstract Nimbus-7 satellite observations are used to determine the relationship between the total longwave radiation flux and the radiance in the 10-12 μm infrared window. The total longwave fluxes are obtained from the earth radiation budget (ERB) narrow-field-of-view (NFOV) observations of total radiance; the IR window radiances are those measured by the Temperature Humidity Infrared Radiometer (THIR). Regression equations are obtained relating the total flux equivalent brightness temperatures to the radiance equivalent brightness temperature of the IR window. These empirical equations are compared to similar regression equations based on radiative transfer calculations for a large sample of atmospheric soundings. The latter theoretical equations are used by NOAA in the processing of IR window observations from operational polar orbiting satellites to obtain total longwave flux estimates. The observational results indicate that there is a very high correlation between the flux equivalent brightness temp...