AN ALGORITHM FOR RETRIEVING VERTICAL WIND PROFILES FROM SATELLITE-OBSERVED WINDS OVER THE INDIAN-OCEAN USING COMPLEX EOF ANALYSIS

With an aim to exploit current satellite observations for determining vertical wind profiles, the authors have carried out a complex empiric al orthogonal function (CEOF) analysis of a large number of radiosonde observations of wind fields over the Indian Ocean. This analysis sugg ests that the first two CEOFs explain more than 80% of the total varia nce. While the first principal component is highly correlated with the upper-level winds at 250 mb (r = 0.95), the second one is well correl ated with the 800-mb winds (r = 0.82). This analysis leads to a retrie val algorithm that ensures the retrieval of vertical profiles of winds , using satellite-tracked cloud motion vector winds. Assuming that acc urate measurements of wind are available at the above-mentioned levels , the rms error of retrieval for each component of wind is estimated t o range between 2 and 6.5 m s(-1) at different levels, which is much l ower than the natural variance of wind at these levels. To construct a better visualization of retrieval, the authors have provided retrieve d and true wind profiles side by side for three typical synoptic condi tions.