Decoding the precipitation dynamics at an East Himalayan glacier using Spectral Bin Classification and Boosted Regression Trees
Year: 2026
Type: preprint
Abstract: The Himalayan high-altitude region exerts a crucial impact on downstream hydrology, where meteorological conditions decisively govern glacier mass balance at sites like the Yala glacier. Because glacier mass is highly dependent on precipitation type, snowfall enhancing accumulation and rainfall accelerating reduction which indicates that the understanding atmospheric drivers is critical. Across all four seasons, relative humidity ( RH ) acts as the most immediate and dominant driver of snowfall, requiring high-moisture states ( RH > 80%) and varying by temperature range: lower temperatures (T1: -18 o C to -5.1 o C) require a mean RH of 86.5 ± 0.9%, while near-freezing temperatures (T2: -5 o C to 0 o C) demand a higher mean RH of 94.5 ± 0.3%. While solar incoming radiation S inc consistently suppresses snowfall due to daytime heating, dew point temperature ( T d ) serves as a steady positive background predictor, and ambient temperature transitions from a negligible factor in winter to a strong inhibitor during the monsoon. Boosted Regression Trees (BRTs) modeling indicates that these temperature variations are overwhelmingly driven by outgoing longwave radiation ( L out , 65–80% importance), whereas RH dynamics are dictated by incoming longwave radiation ( L inc ) and precipitation type, with L inc becoming the solo dominant driver (≈ 70%) during the monsoon and post-monsoon periods. Ultimately, seasonal snowfall distribution between the T1 and T2 ranges shifts from a T2 dominance in winter to a T1 dominance by post-monsoon, establishing a balance where normal days experience strong diurnal cycles that increase glacier mass, while anomalous "Special day" warming events shift temperatures above freezing and accelerate glacier mass reduction.
Source: Research Square
Author: Nilamoni Barman
Institution: Central Ground Water Board
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: green
OpenAlex ID: W7204262102