TEMPERATURE CONTROLS ON SEASONAL SNOW VARIABILITY IN THE TUPALANG RIVER BASIN

Abstract

This study examines whether recent snow variability in the Tupalang River Basin is associated more strongly with temperature or moisture conditions. Daily MODIS snow data for 2001 to 2025 were summarized into annual, spring, winter, and persistent-snow indicators. ERA5-Land, CHIRPS, and TerraClimate supplied temperature, precipitation, maximum snow water equivalent, and runoff-proxy series. Snow-area slopes were negative in all four seasonal definitions, although none was statistically significant. Annual mean temperature increased significantly by 0.041 degrees C per year. Temperature had stronger relationships with snow area than precipitation: the coefficients were -0.6899 for annual conditions, -0.7631 for spring, and -0.7614 for winter. Maximum snow water equivalent was positively related to spring snow area at r equal to 0.6513. The mean elevation of detected spring snow also increased in slope terms and was positively associated with spring temperature. The results show a clear temperature sensitivity in year-to-year snow conditions, but they do not establish a significant long-term decrease in basin-wide snow area. For water planning, the indicators should be combined with measured discharge and station observations before they are used to infer changes in seasonal water supply.