Report on the National Workshop on

Bay of Bengal Monsoon Experiment (BOBMEX)- Initial Results

Preamble:

The Bay of Bengal Monsoon Experiment (BOBMEX) is the first ocean-atmosphere field experiment conceived under the Indian Climate Research Programme (ICRP). The Earth System Science Division of the Department of Science and Technology (DST), Government of India has co-ordinated this first Indian national experiment involving several organisations, each contributing their physical infrastructure, expertise and interest. The Indian Institute of Science (IISc.), Bangalore, National Institute of Oceanography (NIO), Goa, Naval Physical Oceanographic Laboratories (NPOL), Kochi, India Meteorological Department (IMD) and Andhra University, Visakhapatnam provided the necessary scientific / technical leadership. The BOBMEX has the following major objectives:

• To study the organisation of the large scale convective systems over the Bay of Bengal and their intra-seasonal fluctuations under the changing environment of air-sea interactions.

• Fluctuations of surface fluxes and their relationship with atmospheric and oceanic characteristics during different phases of convection.

• Role of low-frequency intra-seasonal fluctuations in the circulation and thermal stratification of the waters over the Bay of Bengal.

• Atmospheric long-wave radiation and albedo fluctuations over the Bay of Bengal.

• Coupling between the atmosphere and the ocean during different weather episodes over the Bay of Bengal and adjoining coastal regions.

• Heat and fresh water balances of the Bay of Bengal.

• Variability of upper ocean currents in relation to changing wind and thermodynamic forcing on the Bay.

• Relation between marine Sulphur emissions (DMS & DMSP) and aerosols in the atmospheric boundary layer over the ocean.

Implementation of BOBMEX

The BOBMEX observations were designed to characterise the variability of the relevant thermodynamic parameters of the upper ocean and the atmosphere on time scales from hours to weeks. To facilitate the preparations for the BOBMEX, a pilot experiment was carried out during 23 Oct-12 Nov. 1998 in the south-central Bay of Bengal. Another 45 day’s long observational programme, namely BOBMEX-99 was organized during 15^th July to 31^st August 1999 within the established phase of the summer monsoon cycle over India. Observational period was focused on all aspects of the intra-seasonal variability of the monsoon, including the low frequency 30-40 days oscillation in the monsoon. Time series measurements of all components of atmosphere in the marine boundary layer,