Sherin Hassan Bran, National Astronomical Research Institute of Thailand, Chiang Mai University, Thailand

Atmospheric aerosols are climate forcing agents that play an important role in regional and global climate change by modifying cloud properties, thus affecting optical and radiative properties through scattering and absorption of solar radiation (IPCC, 2013). In the present study, the temporal distribution of aerosol optical properties over northern Thailand were studied. The study was done during the warm dry season (March-May) of 2019. For the study, aerosol optical properties, such as aerosol optical depth (AOD) and single scattering albedo (SSA) were obtained from three AERONET stations over this region. The study stations are Chiang Mai (urban), Fang (rural) and Doi Ang Khang (complex terrain). To study the aerosol-radiation interactions and the influence of emission sources in the aerosol optical properties, we used a regional chemical transport model, the weather research and forecasting model coupled with chemistry (WRF-Chem). The model simulations were run from March to June, where May to June is considered as the transition phase of dry season to wet season. High values of AOD (0.5-2.8) were found during March-April over Fang, with the highest AOD of 2.8 observed on the 28th of March, 2019. The comparison statistics of AOD showed that, the index of agreement (IOA) between simulated and observed AOD was found to be 0.71 during the study period. The simulated AOD was able to follow the pattern of observations, though the model underestimated the observations. The detailed results of the spatio-temporal distribution of aerosol optical properties, aerosol mass concentrations and its effect on radiation over this region will be presented and discussed.