Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB): An overview

Abstract

During March-May 2006, an extensive, multi-institution, multi-instrument, and multi-platform integrated field experiment 'Integrated Campaign for Aerosols, gases and Radiation Budget' (ICARB) was carried out under the Geosphere Biosphere Programme of the Indian Space Research Organization (ISRO-GBP). The objective of this largest and most exhaustive field campaign, ever conducted in the Indian region, was to characterize the physico-chemical properties and radiative effects of atmospheric aerosols and trace gases over the Indian landmass and the adjoining oceanic regions of the Arabian Sea, northern Indian Ocean, and Bay of Bengal through intensive, simultaneous observations. A network of ground-based observatories (over the mainland and islands), a dedicated ship cruise over the oceanic regions using a fully equipped research vessel, the Sagar Kanya, and altitude profiling over selected regions using an instrumented aircraft and balloonsondes formed the three segments of this integrated experiment, which were carried out in tandem. This paper presents an overview of the ICARB field experiment, the database generated, and some of its interesting outcomes though these are preliminary in nature.The ICARB has revealed significant spatio-temporal heterogeneity in most of the aerosol characteristics both over land and ocean. Observed aerosol loading and optical depths were comparable to or in certain regions, a little lower than those reported in some of the earlier campaigns for these regions. The preliminary results indicate: • low (< 0.2) aerosol optical depths (AOD) over most part of the Arabian Sea, except two pockets; one off Mangalore and the other, less intense, in the central Arabian Sea at ∼ 18 • N latitude; • HighÅngström exponent in the southern Arabian Sea signifying steep AOD spectra and higher abundance of accumulation mode particles in the southern Arabian Sea and off Mangalore; • Remarkably lowÅngström exponents signifying increased concentration of coarse mode aerosols and high columnar abundance in the northern Arabian Sea; • Altitude profiles from aircraft showed a steady BC level up to 3 km altitude with structures which were associated with inversions in the atmospheric boundary layer (ABL); • A surprisingly large increase in the BC mass fraction with altitude; • Presence of a convectively mixed layer extending up to about 1 km over the Arabian Sea and Bay of Bengal; • A spatial off shore extent of < 100 km for the anthropogenic impact at the coast; and • Advection of aerosols, through airmass trajectories, from west Asia and NW arid regions of India leading to formation of elevated aerosol layers extending as far as 400 km off the east coast.

Atmospheric pollutant outflow from southern Asia: a review

“…During the campaign, the elevated pollution layer was observed in various aerosol and trace gas measurements from several platforms, and it quickly became clear that for many components, the majority of the outflow (e.g., in terms of AOD or component mass) occurs in this elevated layer, rather than directly in the MBL (e.g., Manghnani et al, 2000;Lelieveld et al, 2001;Ramanathan et al, 2001;Léon et al, 2001;Reiner et al, 2001;Müller et al, 2001a, b;Sheridan et al, 2002;Chazette, 2003;Franke et al, 2003); similar observations have also been made since INDOEX, for example lidar aerosol vertical profile measurements clearly showing this phenomenon at Pune (Raj et al, 2008) and off both the east and west coasts during ICARB (Satheesh et al, 2009). Furthermore, although most of the studies of the elevated layers have been based on the INDOEX observations in the Arabian Sea, similar elevated pollution layers have also been observed off the east coast of India over the Bay of Bengal, especially during ICARB (e.g., Moorthy et al, 2008;Babu et al, 2008;Murugavel et al, 2008).…”

Aerosol black carbon characteristics over a high-altitude Western Ghats location in Southern India

“…Aethalometer is a field rugged instrument extensively used across the aerosol research community for continuous measurements of ambient BC mass concentration over a variety of environments (e.g. Hansen et al, 1984;Novakov et al, 2003;Moorthy et al, 2008;Babu et al, 2011a;Gogoi et al, 2014). The instrument measures attenuation of light beam at seven different wavelengths, namely 370,470,520,590,660,880 and 950 nm, transmitted through the aerosols deposited continuously on a quartz fibre filter tape (Hansen et al, 1984).…”

Atmospheric Fine Mode Particulates at Eastern Himalaya, India: Role of Meteorology, Long-Range Transport and Local Anthropogenic Sources

“…The regional and synoptic characteristics of size-segregated fine mode aerosol and their significance are required to be investigated (Moorthy et al, 1998(Moorthy et al, , 2007(Moorthy et al, , 2008, while this kind of study has been done at fewer stations over Himalayan regions of India (Sellegri et al, 2010). The anthropogenic activities such as increasing vehicular traffic due to increased tourism-related activities, biomass burning and fuel wood burning for cooking and heating are the causes of concern for most of the Himalayan high altitude hill stations in India which apparently look like pollution-free regions as situated far away from the Indian mega-cities.…”