Snow Persistence Dynamics in the Indian North Western Himalaya (2000– 2024): A MODIS-Based Trend Analysis

Abstract. Snow persistence is a key indicator of cryospheric variability and strongly influences hydrological processes and water availability in mountainous regions. This study examines the spatio-temporal dynamics and long-term trends of snow persistence across the North-Western Himalaya (NWH), including Ladakh, Jammu & Kashmir, Himachal Pradesh, and Uttarakhand, during 2000–2024 using MODIS-derived snow cover products (MOD10A1F and MYD10A1F). Annual snow persistence was estimated by aggregating daily cloud gap-filled snow cover data, while elevation-dependent variability was analyzed using SRTM DEM data. Temporal trends and their statistical significance were assessed using the non-parametric Mann–Kendall test. Results reveal a strong altitudinal influence on snow persistence. High-elevation regions (>4500 m) exhibit near-perennial snow cover exceeding 150 days annually, whereas mid- and low-elevation zones show lower persistence and greater spatial fragmentation. Approximately 29% of the NWH displays statistically significant trends, predominantly negative, indicating a widespread decline in snow persistence at an average rate of ~3.2 days per year. Regionally, Ladakh shows the highest proportion of declining trends, followed by Uttarakhand, Himachal Pradesh, and Jammu & Kashmir. Spatio-temporal analysis of Snow-Covered Area (SCA) indicates a consistent seasonal cycle but also highlights earlier snowmelt, reduced snow retention duration, and increased intra-seasonal variability in recent years. The findings emphasize the vulnerability of mid-elevation zones (2000–4000 m) to climate variability and their implications for downstream water resources and climate adaptation planning.