Earth, Atmosphere & Environment Sciences
Title : | Quantifying The Role Of Various Cloud/Rain Processes On The Variability Of Stable Oxygen And Hydrogen Isotopes Of Tropical Rainfall |
Area of research : | Earth, Atmosphere & Environment Sciences |
Focus area : | Atmospheric Science and Hydrology |
Principal Investigator : | Dr. Midhun M, Cochin University Of Science And Technology, Kochi, Kerala |
Timeline Start Year : | 2024 |
Timeline End Year : | 2027 |
Contact info : | midhun.ndr@gmail.com |
Details
Executive Summary : | Variations in the stable oxygen/hydrogen isotopic composition, usually represented by heavy isotopic content as δ18O or δD, are widely used as a tracer in hydrological and paleoclimatic studies. In the tropics, the observed negative relationship between climatological monthly δ18O and precipitation amount, called the amount effect, is widely used to infer the past climate. Such studies have enormous implications for Indian Summer Monsoon (ISM) studies as they provide a baseline for the monsoon’s natural variability. One of the primary sources of errors in paleoclimate studies is the reliability of the amount effect. During the last two decades, there have been many studies on the variability of ISM δ18O, and most of them challenge the reliability of the amount effect. Therefore, it is necessary to understand the present-day isotopic variability in the ISM region to improve the fidelity of paleoclimate reconstruction. Towards this goal, the current study addresses the isotopic variability associated with various types of rainfall in south peninsular India. The study will use direct measurements of rain and vapour isotopes and micro-meteorological and micro-physical parameters. This work will be the first such attempt to combine direct observations of sub-cloud layers and microphysical properties such as humidity, temperature, and droplet size distribution with high-resolution vapour and rain isotopic measurements. The proposed work also plans to characterize the Arabian sea vapour isotopic composition, a major source of rainfall over the western Ghat region, using in situ observations. After generating 2-3 years-long high-resolution vapour and rain isotope data, we will validate the latest generation of CMIP-6 class isotope-enabled General Circulations Models (GCM). The expected outcome from this study is the generation of a unique set of high-resolution isotopic and meteorological data. The new dataset would enable us to make more targeted paleoclimate reconstructions from the Western Ghats. The new dataset would also help climate modelers optimize the isotopic physics used in GCMs. The study will be carried over Kochi, where three-dimensional winds (zonal and vertical) are continuously tracked using CUSAT’s Stratosphere Troposphere Radar. Combining radar data with data generated during the proposed study can be utilized in understanding the isotopic variability associated with strong convective updrafts and downdrafts during monsoon rain and cyclonic storms. This is a challenging unresolved puzzle in the water isotope community, and it will be addressed in future studies. |
Co-PI: | Dr. Lekshmy P R, Cochin University Of Science And Technology, Kochi,Kerala-682022, Dr. Satheesan K, Cochin University Of Science And Technology, Kochi, Kerala-682022 |
Total Budget (INR): | 27,22,760 |
Organizations involved