蒙古高原积雪消融对气温的响应

Using MODIS snow product data, this study investigates the spatiotemporal variation characteristics of the snowmelt period over the Mongolian Plateau during the 2003-2022 hydrological years. The movement of the snowmelt line toward higher latitudes and its response to air temperature are tracked and analyzed at 15-day inter- vals. The results show that: (1) The proportion of snow-covered area to the total area of the Mongolian Plateau during the 2003-2022 hydrological years ranged from 55.59% to 87.61%, with the smallest snow cover in 2018 and the largest in 2009. Additionally, over the past 20 years, the snowmelt start time on the Mongolian Plateau ex- hibited a significant advancing trend at a rate of 0.18 days per decade (P<0.05); while the stable snow-cover area showed a delaying trend. (2) Spatially, snowmelt occurred significantly later in northern regions of the Mongolian Plateau compared to southern regions. Stable snow-cover areas were primarily concentrated in the western Mon- golia and northeastern, Inner Mongolia, where snowmelt times were generally later. Approximately 64.9% of these areas showed an advancing trend in snowmelt, while regions with delaying trends were mainly distributed in the northwestern part of the study area. (3) Observational analysis at half-monthly scales from January during the winter season revealed that the movement of the snowmelt line demonstrated successive synchronicity with the -5 and 0 isotherms. Correlation coefficients between snowmelt line positions and temperature, except for the year 2018 (with the least snow cover); generally fell within the higher range of 0.72 to 0.98, indicating that temperature is a key factor influencing the position of the snowmelt line.