Abstract
The effect of the time change of static stability and wind shear on a two-level quasigeostrophic baroclinic wave is considered. First, by keeping the wind shear as a constant the effect of the increase of static stability is that the amplitude of the temperature wave reaches a maximum first while that of the stream field is still amplifying and, as that of temperature wave reaches a minimum, that of the stream field becomes a maximum, and both are in phase. Next, by keeping the static stability as a constant, a life cycle of disturbance associated with the time change of wind shear is obtained. In this case the maximum amplitude of the wave appears at about 6 days and the life cycle is about 11 days for reasonable values of the model parameters. Finally, both effects are considered. The results show that as the wind shear decreases, the static stability increases, and the percentage change of wind shear is larger than that of static stability.
This paper is not an entirely convincing analysis of the finite amplitude dynamics of an unstable wave in the two-level model, but rather a pedagogically useful approximate theory in which the retention of some terms rather than others is justified in view of the plausibility of the results.
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Tang, CM. The influence of the time change of static stability and wind shear on baroclinic waves. PAGEOPH 118, 706–719 (1980). https://doi.org/10.1007/BF01593024
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DOI: https://doi.org/10.1007/BF01593024