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| Abstract Submission No. | ABS-2022-07-0140 |
| Title of Abstract | Spatio-temporal variation of atmospheric DMS over the Bay of Bengal during the post-monsoon season and the role of biological productivity |
| Authors | Mansi Gupta*, Nidhi Tripathi, Arvind Singh, L K Sahu |
| Organisation | Physical Research Laboratory, Ahmedabad; IIT Gandhinagar, Gujarat |
| Address | D-106, PRL staff residency, Navarangapura Ahmedabad, Gujarat, India Pincode: 380009 Mobile: 6303283421 E-mail: mansigupta@prl.res.in |
| Country | India |
| Presentation | Oral |
| Abstract | Dimethyl sulfide (DMS) is a biogenic volatile organic sulfur compound primarily present in the marine atmosphere at trace levels. DMS in seawater is primarily produced from the decomposition of the algal metabolites such as dimethylsulfoniopropionate (DMSP) which in turn is produced by phytoplankton. DMS is the major precursor of secondary Sulphur aerosols in the marine atmosphere. Therefore, DMS plays a significant role in modulating cloud coverage and the radiation balance of the Earth. The air-sea exchange is the main source of DMS in the marine atmosphere, which strongly depends on the biogeochemical processes in the surface seawater as well as physical and environmental parameters like wind turbulence, wave breaking, sea surface temperature, solar flux, etc. The biogeochemistry of carbon and nitrogen compounds are reasonably known, particularly in the northern Indian Ocean, our understanding of sulfur compounds is limited. Despite being critically important in chemistry-climate interactions, the in situ measurement-based studies of DMS in the marine atmosphere over the northern Indian Ocean are very limited. The In-situ, high spatio-temporal resolution measurements of DMS in the marine atmosphere over the Bay of Bengal (BoB) and Andaman Sea (AnS) were conducted using online sulfur trace gas analyzer during the post-monsoon season (September-October 2021) onboard ORV Sagar Kanya (SK) between 10-14oN and 80-95oS. The significantly elevated levels of DMS were observed over the central to southern AnS with concurrent dense bloom patches and extreme weather conditions (turbulent sea). These regions of AnS are upwelling zones and therefore, experience high biological productivity. Our measurements reveal distinct spatiotemporal variations in the atmospheric DMS, with strong diurnal patterns over the southern BoB and AnS. The biological parameters were also investigated to identify and classify the DMS producing species in the region. A detailed result and discussion on DMS distributions, including its latitudinal, meteorological dependence, role of biogeochemistry, and the estimation of the air-sea exchange flux will be presented over the Bay of Bengal and the Andaman Sea. |