TEMPORAL RECORD OF TROPOSPHERIC OZONE CONCENTRATION OVER PAKISTAN DURING THE TIME PERIOD OF 2004-2014

Abstract

This study uses the tropospheric ozone data derived from combined observations of OMI/MLS instruments by using tropospheric ozone residual (TOR) method. Main objective was to to study the spatial distribution and temporal evolution in the troposphere ozone columns in Pakistan during the time-period of 2004 to 2014. Results showed an overall increase of 3.2 ± 2.2 DU in tropospheric ozone columns in Pakistan. The spatial distribution showed high concentrations of ozone columns in the Punjab and southern Sindh consistent to high population, urbanization and extensive anthropogenic activities and exhibited statistically significant temporal trends. Similar seasonal variations of maximum in summer and minimum during winter months are observed in all regions of Pakistan. These variations are driven by various factors such as seasonality in UV-B fluxes, seasonality in ozone precursor gases such as NOx and VOCs and agricultural fire activities in Pakistan. A strong correlation of 96% was found between fire events and tropospheric ozone columns in Pakistan. Furthermore, the influence of UV-B radiations in the tropospheric ozone production in different regions of Pakistan is discussed.