A Time Dependent Model of the Atmospheric Response to Midlatitude Heating with Various Zonal Structures

[摘要] The transient atmospheric response to midlatitude heating is examined analytically by means of a time dependent, zonally periodic, two level model (with and without surface friction). A Fourier series technique is used to find the solutions corresponding to segmented cosine and segmented sine zonal heating structures, both with cosly meridional dependence.The height at which the thermodynamic equation is applied is found to be crucial in determining the response of the model. When the heating is entered into the model near to the surface (Model 2), unstable modes are prevalent sooner than they would be when the heat forcing is applied at a higher level (Model 1).For both Models 1 and 2, two cases dependent on the meridional wavenumber 1 and independent of the tonal width of the heating structure x0, emerge. For small scale meridional heating structures (case 1; large 1), the response consists of an upper level high and a lower level low which propagate eastward with time. For large scale meridional heating structures (case 2; small 1) the response essentially consists of a zonal wavenumber 3-4 perturbation superimposed on the solution for case 1.An analysis of the baroclinic instability observed in the solutions is presented for each model and case described above.

[学科分类] 大气科学