A Two Level Model of the Steady State Response of the Atmosphere to Midlatitude Heating with Various Zonal Structures

[摘要] The effect of the horizontal structure of midlatitude oceanic heating on the stationary atmospheric response is examined by means of two simple two level quasigeostrophic β-plane channel models. Solutions are obtained for three non-periodic zonal heating structures (line source, segmented cosine, and segmented sine), and these are compared with the results for a continuously stratified model. Little difference is observed between the solutions for these two different models.There are two cases which emerge in obtaining analytic solutions. In case 1, for large meridional wavenumbers, there exists a large local response and a constant downstream response. In case 2, for small meridional wavenumbers, the far field response is now sinusoidal. A critical wavenumber separating these two cases is obtained.The effect of oceanic heating on the atmosphere over the Kuroshio region is examined in an attempt to explain the large correlations observed between winter Kuroshio oceanic heat flux anomalies, and the winter atmospheric surface pressure and 500 & 700mb geopotential heights, both upstream and downstream of the heating region. It is found that the model response is consistent with the observed correlations. When western North Pacific heating and eastern North Pacific cooling are introduced into the model, a large low pressure response is observed over the central North Pacific. This feature is in excellent agreement with the observed correlations.

[学科分类] 大气科学