Title : Understanding daily/monthly scale variation in hydro-meteorological processes during Indian Summer Monsoon through observed and model water isotope data
Stable isotopic ratio (2H/1H and 18O/16O) of atmospheric vapour and rain change during various hydro-meteorological processes viz, evaporation, advection, condensation, moisture recycling, etc. The relationships between isotope ratio and various local meteorological parameters have long been used for climate reconstruction on different time scales. Several recent studies have further documented that the regional-scale atmospheric circulation primarily controls water isotope variability. Therefore, efforts have been made to simulate water isotope ratios constraining atmospheric circulation in various general circulation models (GCM). The historical simulations of these models are often compared with the isotope ratios of various natural archives to reconstruct past atmospheric circulation. These isotope-enabled GCMs depend on the parameterization of the processes mentioned earlier, which are often formulated with several simplifications. These simplifications may incorporate considerable biases and errors. Indian summer monsoon (ISM) is a prototype of complex monsoon dynamics involving considerable heterogeneity in moisture sources and rainout mechanisms. The talk will cover how this heterogeneity is reflected in observed and model water isotope values of ISM on a daily/monthly scale. The talk will further elucidate how quantitatively one can assess the role of various processes in region-specific water isotope biases. Hence, both users and modelers will be benefitted from the talk. While the users will get a scope to evaluate the models for ISM critically, the modelers may get a guideline on how to improve their models by incorporating the complexities of monsoon dynamics.