Observational evidence of solar dimming: Offsetting surface warming over India

Monthly mean surface reaching solar radiation ( S) measurements under all sky conditions have been evaluated for 12 stations, which are widely distributed over the Indian region, for the period 1981-2004. It is noteworthy that all the stations showed decline in S ranging from -0.17 to -1.44 W/m(2) per year. The average solar dimming observed over India for the period 1981-2004 is similar to -0.86 W/m(2) per year while during winter, pre-monsoon and monsoon seasons it is similar to - 0.94, similar to -1.04 and similar to - 0.74 W/m(2) per year, respectively. Decadal monthly mean S for the two decades 1981 - 1990 and 1991 - 2000 showed strong decline during the second decade with an average reduction of 5% per two decades. Despite the drastic decrease in S, the all India averaged surface maximum and minimum air temperatures have been increasing. But, the change in increase in maximum temperature from the first decade to second decade is only marginal under the present situation of drastic increase in greenhouse gas emissions, while the increase in minimum temperature has been doubled.