Troposphere-Stratosphere (Surface-55 km) Monthly Winter General Circulation Statistics for the Northern Hemisphere-Four Year Averages

Abstract

Monthly mean Northern Hemisphere general circulation statistics are presented for the four-year average December, January and February months of the winters 1978–79 through 1981–82. These calculations start with daily maps for eighteen pressure levels between 1000 and 0.4 mb of Northern Hemisphere temperature at 1200 GMT that are supplied by NOAA/NMC. Geopotential height and geostrophic wind are constructed using the hydrostatic and geostrophic relationships, respectively. Fields presented in this paper are zonally averaged temperature, mean zonal wind, and amplitude and phase of planetary waves with zonal wave-numbers 1-3. Diagnostic quantities, such as the northward fluxes of heat and eastward momentum by standing and transient eddies along with their wavenumber decomposition and Eliassen-Palm flux propagation vectors and divergences by the standing and transient eddies along with their wavenumber decomposition, are also given. The observations indicate that polar temperatures in the lower stratosphere are warmer in February than in December or January. Upper stratospheric mean zonal winds are also strongest in December and weakest in February, as is consistent with the thermal wind relationship. Stationary planetary waves are observed to have the largest amplitudes in January. Stationary eddy heat and momentum fluxes and the Eliassen-Palm fluxes from the standing eddies are largest in January. This is consistent with the large amplitude wavenumber 1 in January. The results of this paper are compared with those of several other works.