A MERIDIONAL AEROLOGICAL CROSS SECTION IN THE SOUTHWEST PACIFIC

Abstract

From recent aerological information a meridional section has been drawn through the southern hemisphere in the region of longitude 150°E. Its most striking feature, the coldness of the extratropical troposphere, is mainly ascribed to the higher albedo of the southern hemisphere. A break in the height of the southern troposphere between 30°S and 40°S is established statistically. In winter the average tropopause descends very little between 35°S and 55°S. The poleward slope of the mean isobars, and consequently the westerly component of the mean geostrophic wind, is stronger in summer than in the northern hemisphere summer; in the winter seasons the difference between the hemispheres is less. The bulk of the southern troposphere in temperate and subpolar latitudes is marked by small differences between summer and winter. The jet stream appears clearly in the seasonal wind fields for both summer and winter. Its intensity and low latitude in winter is surprising; but the latter feature is confirmed by the available radar wind observations. In winter a somewhat problematical minimum of the zonal wind component is found in temperate latitudes.