Improvements in the degree-day model, incorporating forest influence, and taking China’s Tianshan Mountains as an example

Abstract

Study regionKunes River Basin in the western Tianshan Mountains, China. Study focusThe study used atmospheric meteorological data such as temperature, radiation and snow melt rate for areas with different degrees of openness. The climatic parameters, snow melt process, and major environmental controls were studied. By analysing an improved degree-day model that simulated the forest subcanopy, a subcanopy snowmelt model was constructed. New hydrological insights for the regionThe net shortwave radiation of snowy subcanopy surfaces is lower than that of open sites, whilst the net longwave radiation is higher. This suggests that the influence of longwave radiation on the snowmelt process in the subcanopy is greater than that of shortwave radiation. Furthermore, due to the relatively high night-time temperatures in the subcanopy, the influence of the water recession process was significant. In this study, net longwave radiation and water recession were added to a traditional degree-day model. The simulation showed that the improved degree-day model responded well. The R2 of each station was > 0.88, the Ens was > 0.87, and the PBIAS was 0.63 %− 8.44 %, providing a simple and feasible method for the simulation of snowmelt runoff.