The Mean Upper-Air Flow in Southern Hemisphere Temperate Latitudes Determined from Several Years of GHOST Balloon Flights at 200 and 100 mb

Abstract

Abstract Five years of constant-level balloon (GHOST) flights at 200 mb and three years of flights at 100 mb in Southern Hemisphere temperate latitudes furnish information on the mean variation with time of year and longitude of zonal and meridional winds. As found previously from one year of data at 200 mb, there is evidence of a large annual variation in mean meridional wind at these surfaces, with the GHOST balloons moving toward the South Pole at a mean speed exceeding 20 cm sec−1 in the Southern Hemisphere winter and toward the equator at a similar speed in summer. The poleward flow in winter is associated with relatively strong west winds. The semiannual variations in meridional wind are indicated to be out of phase at 200 and 100 mb, with the maximum poleward flow occurring near the equinoxes at 200 mb and near the solstices at 100 mb, implying the existence of meridional circulation cells with flows of opposite sense in the upper troposphere and lower stratosphere. The west wind is strongest over ...