Aitken nuclei measurements over the sea region during INDOEX IFP-99

A portable gardner counter was used on board ORV Sagar Kanya to obtain Aitk en nuclei (AN) data over the Arabian Sea and the Indian Ocean during 20 Jan uary-12 March 1999, The study revealed that the number concentration of AN gradually decreased as the ship moved away from the coast and the trend con tinued up to 20 degreesS where the minimum value was observed. To the north and south of ITCZ, the concentrations were higher and inside the ITCZ the concentrations were very low. The diurnal variation of AN indicated high co ncentrations during day time and low concentrations during night time.