Horizontal wavenumber spectra of winds, temperature, and trace gases during the Pacific Exploratory Missions: 1. Climatology

Aircraft-based meteorological and chemical measurements from NASA's Pacific Exploratory Missions provide a suitable database for studying;the climatology of horizontal wavenumber spectra in the troposphere overlying an ocean. The wavenumber spectra of trace gas and meteorological quantities aid in identifying the physical processes producing atmospheric structures as well as provide diagnostics for general circulation models. Flight segments were distributed over altitudes ranging from about similar to 50 m to 13 km and 70 degrees S to 60 degrees N in latitude. The spectra were averaged according to altitude and latitude regions. The wavelength range covered was typically similar to 0.5-100 km. Quantities processed in this way were horizontal velocity, potential temperature, specific humidity, and the mixing ratios of ozone, methane, carbon monoxide, and carbon dioxide. Spectral power and slope tin log-log coordinates) corresponding to the wavelength regime of 6-60 km were tabulated for those measured quantities. The spectral slopes of horizontal velocity and potential temperature were generally close to -5/3 with no transition to a steeper slope at short wavelengths. as seen,in some other studies. Spectral slopes of the tracer species also ranged around -5/3. This agreement in form of the dynamical and tracer spectra is consistent with both the gravity-wave advection and quasi two-dimensional turbulence models. In the upper troposphere the spectral power for all quantities except specific humidity tended to be greater at latitudes higher than 30 degrees compared to latitudes lower than 30 degrees. This latitudinal trend confirms the earlier results of the Global Atmospheric Sampling Program.