Dr. Prosenjit Ghosh (Assistant Professor)

Prosenjit Ghosh obtained his BSc (Geology) (1991) from Hansraj College, Delhi University and MTech in Applied Geology (1994) from University of Roorkee (Uttar Pradesh) and PhD (2000) from Devi Ahiliya Vishwa Vidhyalaya, Indore while working under the supervision of S.K. Bhattacharya at the Physical Research Laboratory (PRL), Ahmedabad. Subsequently, he was Postdoctoral Fellow (2001-2002) at PRL. He was WMO-IAEA post doctoral fellow at Max Planck Institute for Biogeochemistry, Jena with Willi Brand and Caltech postdoctoral fellow with John Eiler. He worked as an Assistant Professor at Tokyo Institute of Technology, Tokyo, Japan during 2006-2007. He joined as an Assistant Professor in the Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science in the year 2007 and became a core faculty at the Centre for Earth Sciences in the year 2008, soon after its creation. He is adjunct faculty in other departments which includes Centre for Atmospheric and Oceanic Sciences and Divecha Centre for Climate Change.
Academic and Research Achievements: Dr Prosenjit Ghosh's main research contribution include: stable isotope applications in the field paleo-climatology, hydrology, paleaoecology, marine, coastal and estuarine system. Alone, he established the first Stable Isotope Laboratory in IISc Bangalore and applied the stable isotope methodology to various fields such as meteorology, atmospheric chemistry, paleoclimatology, archeology, ecology, hydrology, geology and oceanography. His major emphasis is to develop proxies for seasonality reconstruction. Apart from probing various natural archives such as corals, speleothems, lake sediments, soil carbonates and marine sediments, his major objective of research is to decipher modern day seasonal variability and compare this with seasonality in the past, especially monsoons during past 20 Ma. His important discoveries include: clumped isotope technique for estimating past temperatures from measuring stable isotopolgues in carbonates from geological archives. Carbonate paleothermometer based on the ordering of 13C and 18O into bonds with each other in the carbonate mineral lattice is a major advancement in the field of isotope geochemistry and presents a new tool to the geochemical community for deriving temperature information from analysing carbonates of varied origin (ranging from tooth to reveal body temperature to a meteorite enabling determination of fluid interaction temperature). An important agenda of his research and scientific interests has been to develop and expand the knowledge of stable isotope geochemistry to quantify physical parameters responsible for isotopic variability in hydrological and carbon cycle. During his tenure as Assistant Professor at IISc, one of his important achievements was developing an experimental setup to measure small variation in the concentration and isotope ratio in atmospheric CO2, which is one of the prominent green house gases and found responsible for the rise in the global temperature. Along with the student he conducted routine experiments on air samples in flasks and analysed them for both concentration and isotope ratios. Based on variability in concentration and isotopic character, seasonal signatures in four distinct seasons were identified. In addition, based on analyses of air during the morning and afternoon time in a diurnal scale, the role of a nocturnal boundary layer on CO2 concentration build-up during the morning was realized in an urban area. The large range in CO2 concentration and isotope ratios allowed identification of the CO2 source and the average source value is indicative of the contribution from fossil fuel, coal and cement industries. His recent contribution is towards developing a new proxy for reconstruction of seasonal rainfall patterns in southern Indian stations namely, Bangalore, Chennai, Surathkal and Trivandrum. Recent papers from his group used stable isotopic ratios in the growth bands of Land Snail shells to reconstruct weekly and monthly rainfall patterns. This approach of using isotopic ratios in the gastropod growth bands for rainfall can serve as a substitute for filling gaps in rainfall data and for cases where no rain records are available. In addition, they can be used to determine the frequencies and magnitudes of dry spells from the past records. The laboratory he builds provides analytical facility for sample preparation and mass spectrometric analysis of air carbon dioxide, water, sediments and organic matters. Important to mention here his interdisciplinary research approach. Important in this context is his effort in relating the isotopic ratios of commercial bottled water to latitude, moisture source and seasonality in precipitation. The method provided in his contribution can also be used as an important forensic tool for exploring the source location of bottled water. Based on his research interest in understanding the interaction between lithosphere, hydrosphere, biosphere and atmosphere he designed a few new courses for undergraduate and postgraduate levels at IISc; the lists include Earth System Science, Earth Life and Sustainability, biogeochemistry and geochemistry.

Other Contributions: Prosenjit serves in team leader for stable isotope study for the project of IGCP -597, contributor to the CG99 scale (WMO-IAEA) for air CO2 isotopic measurement, served as a member of global COE at Tokyo Institute of Technology.