Investigating the atmospheric energy spectra using ECMWF analysis: Regional dependence

The atmospheric turbulence energy spectrum has been a subject of active research for a long time. Beginning with Kolmogorov’s theory of three-dimensional turbulence, to Kraichnan’s two-dimensional turbulence and its extension to the quasi-geostrophic case by Charney, various theoretical models and hypothesis have tried to explain the energy spectrum slope. However, the success or failure of a theory can only be gauged by comparing its output with actual observational data. Nastrom and Gage were able to do just that by analyzing thousands of flight observation data and plotting the wave number spectra of wind and temperature in 1980’s. But, the flight data was confined only to the upper atmosphere and mostly mid-latitudes of northern hemisphere. We use the high-resolution ECMWF analysis data, as a part of Year of Tropical Convection (YOTC) to study the atmospheric energy spectra over a wide range of conditions. We compared and interpreted the differences of the atmospheric energy spectra in the tropics and mid-latitudes, in the winter (DJF) and summer (JJA), at the surface and in the upper troposphere. Our results conform to the previously observed -3 power law for mid-latitude data in the upper troposphere, but the slope of the energy spectrum from the surface wind data and for the tropics exhibited quite different shapes. The causes of these differences are discussed.