Correlation between black carbon aerosols, carbon monoxide and tropospheric ozone over a tropical urban site

Abstract

Black carbon aerosols plays an important role in the earth's radiative balance and little is known of their concentrations, distributions, source strength, and especially the aerosol chemistry of the developing world. The present study addresses the impact of back carbon aerosols on different atmospheric species like CO and tropospheric ozone over an urban environment, namely Hyderabad, India. Ozone concentration varies from 14 to 63 ppbv over the study area. Diurnal variations of ozone suggest that ozone concentration starts increasing gradually after sunrise, attaining a maximum value by evening time and decreasing gradually thereafter. Black carbon (BC) aerosol mass concentrations varies from 1471 to 11,175 ng m −3. The diurnal variations of BC suggest that the concentrations are increased by a factor of ∼2 during morning (06:00–09:00 h) and evening hours (18:00 to 22:00 h) compared to afternoon hours. Positive correlation has been observed between BC and CO ( r 2=0.74) with an average slope of 6.4×10 −3 g BC/g CO. The slope between black carbon aerosol mass concentration and tropospheric ozone suggests that every 1 μg m −3 increase in black carbon aerosol mass concentration causes a 3.5 μg m −3 reduction in tropospheric ozone. The results have been discussed in detail in the paper.