Indian Ocean Experiment [INDOEX]: An overview

30-39An overview of the Indian Ocean Experiment, INDOEX, the first comprehensive campaign to study aerosol and trace gas distribution in the Indian Ocean Region, is presented. The main phase of INDOEX was in 1999 with a field phase in 1998 and preliminary observations in 1996 and 1997 (mainly because of Indian initiative). This was a major international initiative with participation from many institutions and agencies of India, the USA, Europe, and from Maldives and Mauritius. It was a multi-platform campaign combining ground based, shipborne, satellite and aircraft observations and had the single objective of reducing uncertainties in radiative forcing of aerosols, both direct and indirect. The campaign covered both aerosols and trace gases (O₃, CO, NOx, SO₂ etc), although subsequent analysis has been concentrated more on aerosols than on trace gases. The surprising result of an extensive haze layer with an appreciable component of black carbon, evidence of long distances transport of both aerosols and trace species and possible impacts on climate, health and agriculture have created much interest and some controversy. We present here an overview of some of the results, the implications of these in climate forcing, the unresolved aspects of sources of these pollutants, and a few comments on policy implications