Estimation of Winds at Different Isobaric Levels Based on the Observed Winds at 850 hPa Level Using Double Fourier Series

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Estimation of winds at different isobaric levels based on the observed winds at 850 hPa level using double fourier series

A technique based on the double Fourier series is developed to estimate the winds at different isobaric levels for the limited area domain, 35oE to 140oE and 30oS to 40oN, using the observed winds at 850 hPa level for the month of June. For this purpose the wind field at a level under consideration is taken in the ratio form with that of 850 hPa level and the coefficients of the double Fourier series are computed. These coefficients are subsequently used to compute the winds which are compared with the actual winds. The results of the double Fourier series technique are compared with those of the polynomial surface fitting method developed by Bavadekar and Khaladkar (1992). The technique is also applied for the daily wind data of 11, June, 1979 and the validation of the technique is tested for a few radiosonde stations of India. The computed winds for these radiosonde stations are quite close to observed winds.