The aerosol characterization studies were initiated during the IMAP time initially at two locations of Trivandrum and Ahmedabad. The AOD measurements over these regions have provided understanding on the intra annual and inter annul variability and size distribution of aerosols.

During the last one-decade the development of MWR and establishment of MWR observational net work at 10 locations have been made and are being operated on a continuous mode. With the available long term observational data it is found that across various latitudes the Intra and inter annual variability of AOD are noted. The long-term database however would provide better understanding for use in climate modeling of radiative forcing and Aerosol Climatology Effects (ACE).

The Participation of ISRO in the multi country / institutional campaign in the INDOEX during 1999-2000 have provided valuable insights on the aerosol chemistry and characteristics over the Indian region. The prevalence of " Atmospheric Brown cloud "(ABC) over the Indian region and radiation perturbing constituents like Black Carbon (BC) are the new findings as part of combined campaign results. The contributions of ISRO-GBP have countered the UNEP report on the occurrence of ABC and possible climate impacts due to aerosols.

The high altitude balloon launch studies during the years 1992-93 have confirmed the decline of Ozone depleting Halons in the lower Stratosphere at 38 KM heights as the single most quantitative measurements made from the ISRO-GBP supporting Montreal protocol.

NEW THRUST:

The ISRO-GBP planned to enhance the MWR network of Observations across the country to cover various latitudes and to provide as a basis for ground validation to augment the satellite based retrieval of spectral optical depths and eventually to develop the Aerosol Index Map of Indian on a periodic basis.

The aerosol characterization studies have been given further impetus to study the " Aerosol Radiation Budget Studies"(ARBS) as the constituents have differential radiative and absorbing properties potentially alter the Radiation reaching the surface. Towards this carefully reviewed and identified projects are being proposed to undertake from this current RE 2003-2004.

As a base station for the studies related to aerosols, chemistry and climatology for the long-term observational purpose an ISRO-Laboratory for Aerosols, Radiation and Chemistry (I-LARC) has been proposed to operate from the Port-Blair with the fully autonomous mode of some specific instrumentation well calibrated for making continuous observations on aerosols and chemistry. The center has been strongly recommended and suggested at a national debate and as well by the PMB. Many Institutions are going to utilize the facility for scientific understanding of aerosols and other related climate observations.

The natural and anthropogenic sources of aerosols and their constituents are highly debated and in order to understand the sources and background concentrations a systematic Land Based campaigns on aerosols through Road network and Rail are planned with the multi agency participation.