High-level Summer Warmings & Their Possible Association with Monsoon

39-41The stratospheric and mesospheric warming’s reported in literature refer to winter and spring periods. Seldom there is mention of the occurrence of such warming’s in summer. It is considered that the thermal behaviour of stratosphere and mesosphere over tropical stations in summer may have a bearing, at least on gross scale, on the activity of summer monsoon. With this end in view, the available Soviet rocket data for Thumba (8o32'15”N; 76°51'48”E), of the three summer periods commencing from 1971, are examined. The study revealed the phenomenon of high-level warming’s over the station. The behaviour of the monsoon, when such phenomenon occurred, differed from that of the monsoon when it did not occur. Similar feature was also inferred from analysis of radiosonde data. The problem was further examined througl1 analysis of the rocket data of the pre-summer periods. The possibility of such data reflecting the behaviour of the approaching monsoon was indicated

Singularities in Northeast Monsoon Rainfall of Tamil Nadu

277-280A comprehensive programme of work on the singularities of Indian rainfall, region wise and season wise, making use of time series analysis, has been undertaken. The results of analysis under this programme are now available for rainfall of northeast monsoon in Tamil Nadu. Though periods of peak rainfall on calendar dates which bear association with known periods of occurrence of meteor showers have been identified the study does not support Bowen's meteoric shower hypothesis. The analysis suggested periodicities in the rainfall and these may be responsible for the observed singularities. The influence of localized cyclones contributing to the suggested periodicities cannot be ruled out