Temporal Evolution of Diurnal Cycle of Rainfall Using Rain Gauge Data Over India

Hourly rainfall data from 81 Self Recording Rain Gauge stations were analyzed to study the temporal change of the diurnal cycle of rainfall across India between the two periods: 1969-1991 (past) and 1992-2014 (recent). Except east and northeast (ENE) and west India (WI), majority of the stations showed delayed phase of the diurnal cycle of rainfall in recent period.Both frequency and intensity diurnal cycle contributes to the delayed phase over central India (CI) whereas only the intensity diurnal cycle is responsible for advanced phase over WI. Decrease in the number of heavy rainfall events in the past phase contributes most to the delayed phase in CI while increase in the intensity of heavy rainfall events in the recent phase primarily contributes to the advanced phase over WI. Besides, increase in the number of break days over CI is also responsible its delayed phase. The decrease (increase) in CAPE over WI (CI) is responsible for advanced (delayed) phase.