Some Dynamic and Aerological Aspects of Meteorology over Indo-Pakistan

Chaudhury, Abdul Matin

     The steady flow of air horizontally eastward across the Himalayas and the Tibetan plateau is studied in this dissertation. A single infinite family of patterns in terms of first and second kind Bessel solutions is possible. Over this non-unique pattern an infinite number of arbitrary free oscillations whose amplitudes are not determined by the boundary conditions, may be superimposed. The plateau can thus introduce a very complicated flow pattern, particularly in its immediate vicinity. This complex pattern is quasi-harmonic in the vicinity of the plateau but becomes sinusoidal at a large distance from the plateau. The amplitudes of the wave patterns decrease inversely as the square root of the distance.
     Only the position of the first trough of a particular solution coincides almost exactly with the mean observed positions of the Caspian Sea trough upstream and the Asiatic trough downstream off the coast of Indo-China. This particular pattern is one with first order Bessel solution of the second kind. The computed flow pattern over Indo-Pakistan agrees well with that observed, especially for the winter half of the year when the effect of the plateau is greatest. The free air circulation over Indo-Pakistan is thus to a large extent the result of the mechanical effect introduced by the Himalayas and the Tibetan Plateau north of Indo-Pakistan.
     The effect of the plateau on the east wind . . . [is] also . . . studied. A unique solution in terms of modified Bessel function of second kind (first order) . . . [is] obtained. The character of the modified solution is hyperbolic and decreases exponentially from the plateau, showing that the east wind in a non-divergent barotropic atmosphere when disturbed, cannot execute oscillations but that the disturbance dies down exponentially.
     A mean cross-section over Indo-Pakistan along the meridian 76