On the surface air temperature variation in relation to chlorofluorocarbons over the Indian region

Chlorofluorocarbons (CFCs) are among the greenhouse gases in the atmosphere that contribute to warming. Therefore, an attempt is made in the present study to examine the variation in the surface temperature in relation to CFCs over the Indian region during 1992–2007. Space-time distribution of correlation coefficients (CCs) between CFCs and monthly temperature show positive CCs except pre-monsoon months. From April onwards up to onset of monsoon over the country, CCs are negative. It clearly indicates that higher (lower) temperature values are associated with the lower (higher) values of CFCs in these months. This may be because of convection occurred over the country playing some role in association with CFC. Interannual variation of CFCs has contrasting behavior in the two epochs (1) 1992–1997 and (2) 1999–2007 where the CFCs increase and decrease respectively. It is seen that during increasing phase of CFCs, trends in temperature are also increasing except pre-monsoon months which show negative CCs. Trend magnitudes over the northern latitudes are higher. Though decreasing phase of CFCs show similar features, trend magnitude of temperature have substantially decreased. Regional analysis with temperature homogeneous regions, show positive CCs between CFCs and minimum temperature during most of the months. Analysis with regional maximum temperature shows negative trends starting from the month of May up to the month of July. Though further studies may be needed, the results observed in the present analysis show that the variation in surface air temperature indeed has a certain link with the changes in CFCs over Indian region.

► We examine the temperature variation in relation to changes in CFCs over India.
► It show positive CCs with all-India CFCs except the pre-monsoon (MAM) months.
► Increase in all-India CFCs is seen from 1992 to 1997, afterward decreases continuously.
► During increasing phase of CFCs, temperature show increasing trends except MAM.
► During decreasing phase similar features seen but trend magnitudes decreased.