DIURNAL VARIATIONS OF SEASONAL RAINFALL OVER THE STATE OF HIMACHAL PRADESH AS OBSERVED BY SATELLITE DATA

摘要

Diurnal variations of precipitation during Indian summer monsoon over northwestern Himalayan state are investigated using TRMM 3B42V7 from 1998 - 2013. This paper deals with the spatial and diurnal variations of seasonal rainfall, seasonal extremes and the examination of their trends. A pronounced maxima occurs during late night to early morning hours (0230 - 0530 LT) for elevations up to 2 km whereas secondary maxima peaks during afternoon (1430 - 1730 LT) at regions having altitude 2-4 km. The minimum mean 3-hourly rainfall, intensity -frequency of heavy and very heavy rainfall events is registered at 2030 LT. Precipitation occurs most frequently with high intensity over the western regions of the state. Further, trend analysis did not show any significant trend in mean 3-hourly rainfall and intensity-frequency of very heavy rainfall events. Only significant increasing trend (at 5% significance level) was found in intensity of heavy rainfall events for morning hours. The dominant intensity -frequency peak for heavy rainfall events is at 0530 LT whereas for very heavy rainfall events, it is at 0230 LT.