Influence of the Western Disturbance on Winter Precipitation: Observations over the Central Himalayas using VHF Radar

This study investigates the influence of the Western Disturbance (WD) on atmospheric wind patterns and associated precipitation over the Himalayan region utilizing observations carried out using the ARIES ST Radar (ASTRAD) at Nainital [29.36° N, 79.46° E, 1800 m] during March 2024. The observations reveal that during the WD events, the wind direction was predominantly south westerly/westerly with varying speeds, reaching up to 67 m/s. The HYSPLIT model back-trajectory analysis confirmed that the moisture-laden air masses originated from the Atlantic Ocean. Vertical wind measurements indicated significant atmospheric instability and convection, characterized by updraft and downdraft motions in three distinct height regions between 8 km and 10 km, an updraft between 6 km and 7 km, and another downdraft between 4.5 km and 5 km. The core height region of the subtropical westerly jet (SWJ) embedded in WD and shift in height with maximum wind speed are also identified.