Estimation of Aerosol Radiative Forcing Over an Urban Environment Using Radiative Transfer Model

This study has been carried out to understand the effect of aerosols on the urban climate of Gandhinagar. As a part of it, we have carried out measurements of Aerosol Optical Depth at selected locations of Gandhinagar for winter, summer and post-monsoon seasons of 2017 and 2018, respectively. An analysis of short-wave Aerosol Direct Radiative Forcing (ADRF) is done using these measurements as inputs to the SBDART model. The hourly averaged ADRF of the atmosphere 73.6 Wm−2 in 2017 and 69.6 Wm−2 in 2018, indicates that a high amount of energy was trapped within the atmosphere by aerosols which results in the heating of the atmosphere. This model estimation indicates that atmospheric radiative forcing occurs in all the seasons, but much more strongly during the summer season. A large difference between SURF and TOA forcing in the summer season indicates large absorption of the radiant energy (~95.5 Wm−2) within the atmosphere. Correlation between AOD and aerosol radiative forcing has also been calculated as an attempt is made to estimate the dependency of ADRF on a very import optical property of aerosols.