Planetary Waves at 500 mb in the Southern Hemisphere

Kevin E. Trenberth Laboratory for Atmospheric Research, University of Illinois, Urbana 61801

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Abstract

The zonally asymmetric component of the 500 mb flow in the Southern Hemisphere has been analyzed into wavenumber space, and the annual cycle and interannual variability are documented for the period May 1972–January 1978. The planetary waves 1–3 account for most of the variance and all three waves make important contributions, especially to the interannual variability, although the mean fields are dominated by wave 1. The seasonal variation in all fields is small compared with that in the Northern Hemisphere. In the subtropics, the interannual fluctuations in the planetary waves are mainly coupled to the Southern Oscillation and the wave fluctuations are coupled to those in the mean zonal westerlies.

Abstract

The zonally asymmetric component of the 500 mb flow in the Southern Hemisphere has been analyzed into wavenumber space, and the annual cycle and interannual variability are documented for the period May 1972–January 1978. The planetary waves 1–3 account for most of the variance and all three waves make important contributions, especially to the interannual variability, although the mean fields are dominated by wave 1. The seasonal variation in all fields is small compared with that in the Northern Hemisphere. In the subtropics, the interannual fluctuations in the planetary waves are mainly coupled to the Southern Oscillation and the wave fluctuations are coupled to those in the mean zonal westerlies.

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