Research Projects

The South Asian monsoon, delivering 80% of annual rainfall to the Indian subcontinent, is vital for the region's water needs but is also linked to extreme rainfall events and hydrological disasters. Most hydrological extreme events are caused by synoptic-scale low-pressure systems (LPS) originating over the Bay of Bengal and moving northwestward across central India. LPS-driven disasters are more intense than non-LPS events, highlighting the critical role of LPS in shaping rainfall/hydrological extremes. Thermodynamic factors significantly influence the intensity of LPS-related rainfall, with geographical features like the Himalayan foothills also playing a significant role. Extreme rainfall typically peaks in the southwest quadrant of the LPS vortex, but significant events also occur in the northern regions, which could be due to orographic lifting. Small changes in wind speeds can substantially impact rainfall intensity, yet studies on the orographic impacts of LPS remain limited. Moreover, operational Numerical Weather Prediction (NWP) models often fail to accurately predict LPS genesis, peak rainfall, and spatial distribution, underestimating rainfall intensity by at least 33%. Large-scale climate modes like the Boreal Summer Intraseasonal Oscillation (BSISO), Indian Ocean Dipole (IOD), and El Niño-Southern Oscillation (ENSO) play a vital role in modulating LPS activity. However, the influence of these modes on the frequency and intensity of LPS and their connection to hydrological extremes remains underexplored. To address these gaps, this research proposes a three-phase plan: (i) Thermodynamic and Geographical Analysis: Investigate LPS thermodynamics, interactions with large-scale conditions, and the influence of local topography on extreme rainfall events. (ii) Seasonal Projections: Using seasonal background states to predict interannual variations in LPS activity and hydrological extremes improves preseason risk assessments. (iii) Machine Learning-Based Predictions: Assign machine learning tools to forecast short-term extreme rainfall events by integrating LPS characteristics, large-scale conditions, and topographical influences. This study addresses three key questions: (i) How do LPS thermodynamics and geography influence the location and nature of extreme rainfall events? (ii) How does large-scale monsoon circulation affect LPS intensity, rain rates, and hydrological extremes? (iii) Can LPS-driven extreme rainfall events be reliably predicted in the short term? By enhancing the understanding of LPS dynamics, this research seeks to improve predictions of hydrological disasters, thereby boosting disaster preparedness and mitigation strategies.