Diurnal Variations in Rainfall over Indian Region Using Self Recording Raingauge Data

Diurnal variation of rainfall of different intensities using self-recording raingauge data of about 150 stations spread across India is presented here. Analysis of annual average number of rainfall hours revealed that the highest number (>900) is realized over northeast India, followed by west coast (700-800). Lowest incidence (<100) was found over west Rajasthan. Distribution was nearly similar for hours with rainfall >10, >20 and >30 mm. A zone of less number of hours with different intensities extended from west Rajasthan to west Uttar Pradesh; and another one to south Tamil Nadu through Gujarat, west Madhya Pradesh and the rain shadow zones of Maharashtra, Karnataka and Andhra Pradesh. The percentage of contribution to total annual rainfall by intense rainfall of >20 mm and >30 mm, however, was found to be higher in the low rainfall zones and northwest India. Diurnal variation of rainfall showed prominent maxima in the early morning over northeast India; and in the afternoon/evening over northwest India and interior Peninsula. Coastal areas on east and west coast, however, did not exhibit any significant diurnal variations, but a tendency of higher frequency in the early morning was noticed.