INVESTIGATING CONTRIBUTIONS OF GASES, METEOROLOGICAL PARAMETERS, AND AEROSOLS TOWARDS TROPOSPHERIC OZONE VARIABILITIES OVER MEGACITY LAHORE (PAKISTAN)

We investigated contributions of some tropospheric gases, meteorological parameters, and aerosol burden measured as aerosol optical depth (AOD) towards Tropospheric Ozone (TropoO(3)) variabilities over Lahore by developing a stepwise multiple linear regression model. The tropospheric gases include; Methane (CH4), Carbon Monoxide (CO), Carbon Dioxide (CO2), and Sulphur Dioxide (SO2), whereas the meteorological parameters include; cloud fraction (CLF), outgoing long-wave radiation (OLR), relative humidity (RH), temperature (Temp), and surface wind-speed (WS). Data products of these parameters have been retrieved from various satellite sensors during October 2004 September 2015. Time series distributions of both observed and modeled TropoO(3) concentrations show similar increasing trends except for few months Moreover, monthly-means of these observed and modeled TropoO(3) concentrations indicate similar decreasing trends with maximum during spring and summer (monsoon) seasons. Based upon weighted contributions of standardized regression coefficients, modeled TropoO(3) concentration was found dependent upon OLR[0.458], WS [0.262], CLF [0.256] Tropo SO2[-0.097], Tropo CO [-0.231], and RH[-0.320] out of all parameters used in this study. Modeled TropoO(3) concentrations were validated against an independent source of TropoO(3) concentrations retrieved from original subtracted product of OMI-MLS over Lahore and the results were found in good agreement. The study is unique and would be helpful for further research investigations.