A study of the fluctuations of the wind field over the tropical Indian Ocean

Abstract

Using radiosonde data from six widely scattered stations in the Indian Ocean, an attempt was made to identify quasi-periodic wind oscillations during the 1973-197^ winter monsoon season. The data were analyzed using spectrum analysis and time cross-section analysis techniques. In general, the results of the power spectra computed show a seven-day peak which seems most significant. A fourfive day peak and a thirteen-day peak were also found at some stations. The cross-spectrum analysis shows little correlation of the peaks, indicating uncertainty in the significance of the spectral results. The results of the time cross-section analysis, done over two one-month periods, indicate a possible fluctuation time scale of 10-20 days at most stations; and in many cases, the fluctuations appear to propagate downward. Due to the low density of available stations and the poor quality of the data, the results are considered very tentative. Further study is suggested, but only after the quality of the data can be improved.