Radar Polarimetry to Characterize Overshooting Convection in the Western Ghats of India

This study provides the first high-resolution polarimetric radar observations of Overshooting Convective Storms (OCS) over the Western Ghats (WG), India using the newly installed SSPA-based X-band Radar at HACPL, Mahabaleshwar. Three post-monsoon OCS events (15, 23, and 24 October 2025) were analysed using PPI, RHI, CFAD products and ERA5 Atmospheric fields. All storms exhibited strong vertical growth, with echo-top heights of 17.6–19.8 km (15 Oct), 16.5 km (23 Oct), and 17.8 km (24 Oct), and peak reflectivity values of 59.6, 63.3, and 52.1 dBZ, respectively. Notably, significant reflectivity (>40 dBZ) persisted above 16 km, confirming deep overshooting intrusions. Polarimetric signatures showed clear mixed-phase and ice-growth processes, including KDP up to 3–4° km⁻¹, enhanced ZDR in the rainy regions, and reduced ρhv (0.92–0.96) within convective cores, indicating liquid water content, riming, and graupel/hail production. ERA5 diagnostics revealed favorable conditions for deep convection, with strong mid-tropospheric ascent (–0.6 to –0.8 Pa s⁻¹), high moisture, and pronounced convergence over the WG. These results demonstrate intense post-monsoon overshooting convection in complex terrain and highlight the capability of X-band Polarimetric radar to reveal the storm microphysics and vertical structure in an orographically challenging environment.