Using MODIS derived aerosol optical depth to estimate ground-level PM(2.5 )concentrations over Turkey

Satellite based particulate matter (PM) pollution monitoring on a regional basis is of importance due in part to the adverse health effects of PM. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) derived aerosol optical depth (AOD) data at 3 km and 10 km resolutions from both Terra and Aqua satellites were used, in conjunction with the surface in situ data, to improve the regional distribution of ground-level PM2.5 over Turkey. Five years (2011-2015) of heating season's (15th October to 14th May) in situ PM2.5 measurements from 7 monitoring stations in Ankara and 3 years (2013-2015) of the same data from 13 monitoring stations in Marmara Region were used. Linear and non-linear regression models were used to find the relationship between PM2.5 and AOD data. To improve the correlations between PM2.5 and AOD, the data points affected by free tropospheric long-range transport were removed from the analysis via back trajectory modeling analysis since long-range transport affects AOD more readily than surface PM2.5 data. Using non-linear models with the addition of meteorological parameters such as height of planetary boundary layer, surface temperature and surface wind speed improved the correlations significantly. The best non-linear model can explain 61% (n = 37, R-2 = 0.61, p < 0.001, RMSE = 0.337 mu g/m(3)) of PM2.5 variations at the Edirne Kesan site. It was found that Terra worked better than Aqua. Furthermore, 10-km aerosol products gave better correlations with PM2.5 as compared to the 3-km products. With the aid of spatiotemporal model, PM(2.5 )distribution maps are created for the first time for Turkey.