Computation of divergence and vorticity from observed winds over the Indian region during monsoon

Abstract

Grid point wind data at 1000,850,700,500,300 and 200mb derived from station observations by manual analysis are subjected to finite. Double Fourier analysis, to compute analytically the vorticity and divergence values from the amplitudes of the Fourier components. These are compared with the values obtained by the conventional central difference method. The truncation errors are round to be less than 30 per cent in 9.5 per cent of the cases. The vorticity values are generally ~10^-5 sec^-1 and are about twice that of divergence values. For vorticity values exceeding ~5 X 10^-5 sec^-l in the depression region, the divergence is round to be one order less. For low values of vorticity, i.e., less than ~'5 X 10^-5 sec^-l the divergence is of the same order.