INDOEX IFP-99 was undertaken as part of the international experiment in the Indian Ocean to take observations pertaining to aerosols, radiation, cloud physics and other related meteorological parameters. The important-aim of the INDOEX was to quantify radiative forcing due to natural and anthropogenic aerosols and their feedback on regional and global climate systems. Since prevailing circulation features transports aerosols, it is essential that important synoptic patterns during the expedition phase, i.e. 20 January to 10 March 1999 be examined. Based on the synoptic features it was noticed that crossequatorial flow in lower levels from western Arabian Sea to southern Indian Ocean was significantly higher than the eastern Arabian Sea. Two cyclonic storms, one in the south Bay of Bengal during 1-3 February and another in the south Indian Ocean during 4-13 March were observed. Significant changes in the cross-equatorial flow in the lower/upper tropospheric levels and ITCZ locations were noticed