Global Brightness Temperature Spectra at High Wavenuinbers Utilizing Satellite Microwave Measurements

Abstract

Satellite microwave brightness temperature (radiance) measurements represent weighted mean temperatures in a certain atmospheric layer. The high density of measurements along a polar-orbiting satellite track allows estimates of the brightness temperature variance spectrum at high meridional wavenumbers. Global data from the Nimbus 6 SCAMS microwave instrument sensitive to the 100?300 mb layer have been analyzed for 30 days in August 1975. The results reveal that the brightness temperature variance spectrum can be fit to the form km over the range k=22 to 59 (horizontal wavelengths 1800 to 700 km). Using 95% confidence intervals, the fit yields m = ?3.1±0.3 These results appear to have significance for estimates of energy cascade between different motion scales in the very high wavenumber regime.