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

30-Day Periodicity in Sunspot Activity & Rainfall

215-216An attempt is made to examine short term periodicities, if any, in the sunspot activity and rainfall. The daily mean relative sunspot numbers for July-Sep. during 1961-70 and the daily sunspot means for July-Sep. 1889-1938, as well as the rainfall series of Tamil Nadu for July-Sep. during 1961-70 have been analyzed by power spectrum. The study has suggested that the sunspot activity and the rainfall contain a concurrent 30-day periodicity which is highly significant during the southwest monsoon period (July-Sep.) when the sun remains at all times in the northern hemisphere