The kinetic energy spectrum in the free atmosphere-1 second to 5 years

Abstract

An energy spectrum of wind speed at altitudes from 3 to 20 km is constructed from rawinsonde and aircraft data originating in the U.S.A. and the U.S.S.R. Most of the observations are concentrated near 40" N and cover periods from 1 sec to 5 year. The spectrum is subdivided into three major regions separated by gaps: a sharp annual maximum, a synoptic (or macroscale) maximum at periods from 1-2 months to 3-4 days, and a microscale maximum with periods of 1-3 min. It is shown that the micro-scale maximum is not a permanent feature of the spectrum. Usually high frequency turbulence is supressed by stable stratification in the free atmosphere and its energy is negligibly small. Spectra in the free atmosphere and near the ground are compared. An attempt is made to relate frequency and wave number spectra at synoptic scales.