Studies of trace gases and Aitken Nuclei at inland and coastal stations - A part of INDOEX programme

As a part of the Indian Ocean Experiment (INDOEX) programme, ground-based m easurements of trace gases (SO2, NO2, NH3 and O-3) and Aitken Nuclei (AN) w ere carried out at Pune during March-April 1998, Also, measurements of surf ace ozone and AN were made during 5-10 January 1998, the inter comparison c ampaign of various instruments at Thiruvananthapuram, The mean concentratio ns of SO2, NO2, NH3 and O-3 at Pune were 3.75, 5.81, 3.21 and 57.8 mu g/m r espectively and that of O-3 at Thiruvananthapuram was 44 mu g/m(3) The aver age concentration of AN was about five times higher at Pune (19,000/cm(3)) than that at Thiruvananthapuram (4,400/cm(3)), indicating more pollution at Pune than at Thiruvananthapuram. The diurnal variation of surface ozone sh owed high concentrations during the day and low concentrations during the n ight at both the locations, Diurnal variation of AN at Pune showed a daytim e maximum and a night-time minimum. Whereas, at Thiruvananthapuram night-ti me values were higher than the daytime values which can be attributed to th e influence of the land and sea breeze.