The Behavior of Stationary Waves and the Summer Monsoon

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  • 1 Department of Atmospheric Sciences, University of Washington, Seattle 98195
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Abstract

A linear primitive equation model has been used to simulate the behavior of summer stationary waves in the Northern Hemisphere. Many basic features of the observed summer stationary waves have been reproduced quite well with this model. The role of different forcing mechanisms for the summer stationary waves has been compared. It is found that latent heating plays the dominant role for the formation and maintenance of the summer monsoon circulation in the subtropics, but in high latitudes, where advective processes become more important, topography and sensible heat flux from the surface produce more realistic surface wave patterns than does the latent heating. The performance of the model for different latitude domains is discussed in some detail.

The effects of the mean wind structure on the behavior of stationary waves, especially on horizontal propagation, have been examined. It is found that in summer the latitudinal propagation of stationary waves is mainly northward and hence the influence of low latitudes on high latitudes is more significant than the influence of high latitudes on low latitudes. The mean wind structure, especially the zero wind line in high latitudes, has significant effect on the northward propagation of stationary waves.

Abstract

A linear primitive equation model has been used to simulate the behavior of summer stationary waves in the Northern Hemisphere. Many basic features of the observed summer stationary waves have been reproduced quite well with this model. The role of different forcing mechanisms for the summer stationary waves has been compared. It is found that latent heating plays the dominant role for the formation and maintenance of the summer monsoon circulation in the subtropics, but in high latitudes, where advective processes become more important, topography and sensible heat flux from the surface produce more realistic surface wave patterns than does the latent heating. The performance of the model for different latitude domains is discussed in some detail.

The effects of the mean wind structure on the behavior of stationary waves, especially on horizontal propagation, have been examined. It is found that in summer the latitudinal propagation of stationary waves is mainly northward and hence the influence of low latitudes on high latitudes is more significant than the influence of high latitudes on low latitudes. The mean wind structure, especially the zero wind line in high latitudes, has significant effect on the northward propagation of stationary waves.

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