Abstract
An analysis was made of zonal stationary waves in the Southern Hemisphere midlatitude zone (20°S-60°S) by the use of 3-monthly (90 day) average brightness charts for the two extreme seasons (summer and winter) and one intermediate season of 1969, produced from daily satellite cloud pictures.
Harmonic analyses of average brightness along the four latitude circles reveal the predominance of stationary waves of wavenumber 1, 2, 3, and 4. At the main westerly zone (40°5-50°S), the maximum brightness, which corresponds to the trough of pressure wave, of wavenumber 1 stays in the eastern Atlantic through Indian Ocean, and at the subtropical latitudes (20°S-40°S), it stays in the central Pacific. Wavenumber 2 may be the fundamental mode through the mid-latitude zone with its maxima in the western Indian Ocean and the central Pacific. Wavenumber 3 is superior in the main westerly zone, and its maxima are located in the eastern parts of the three ocean. At the subtropical latitudes, wavenumber 4 is prominent, whose maxima are located in the extremely eastern parts of the three oceans and the central Pacific. These stationary waves (wavenumber 1 to 4) generally show NW-SE tilt. The features of wavenumber 1 and 3 are in good agreement with those depicted from 500mb monthly mean charts by van Loon and Jenne (1972), but the predominance of wavenumber 2 and 4 is also confirmed by the present analysis.
