Latitudinal gradient in aerosol properties over the Indian and Southern Oceans during the austral summer

• Main Authors: Suresh Babu, S., Krishna Moorthy, K., Satheesh, S. K.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Current Science Association 2010
• Subjects: QE Geology; Austral; Indian; Southern Ocean
• Online Access: http://repository.ias.ac.in/69339/; http://repository.ias.ac.in/69339/1/69339.pdf; http://www.ias.ac.in/currsci/25nov2010/1384.pdf

Extensive measurements of columnar aerosol optical depth (AOD), composite (M T ) and black carbon aerosol mass (M B ) concentrations were made over the tropical Indian and Southern Oceans as a part of the Pilot Expedition to the Southern Ocean during the boreal winter. The AOD, M T and M B show large latitudinal gradient towards south up to ITCZ. Beyond ITCZ, up to 56°S, AOD and M B show very low and steady values. However MT shows large variations in the Southern Ocean due to the enhanced production of sea salt aerosols associated with high sea surface winds. The short wave aerosol radiative forcing at the surface over north of equator is in the range – 10 to – 23 W m –2 , whereas that over the Southern Ocean was in the range – 4 to – 5 W m –2 . The corresponding atmospheric forcing was in the range of 6–13 W m –2 and 0.8–1.4 W m –2 . This large north–south change in the aerosol radiative forcing has important implications to the meridional circulation and hence to climate.