Changes in Snow Cover and Snow Water Equivalent Due to Global Warming Simulated by a 20km-mesh Global Atmospheric Model

Abstract

Simulations under present (end of the 20th Century) and future conditions (end of the 21st Century with SRES A1B scenario) by using a 20 km-mesh atmos- pheric general circulation model (AGCM) over 10 years are conducted and the changes in snow due to global warming are investigated. The seasonal march of the snow cover in the present simulation is comparable to that of satellite-based obser- vational data. Distributions of the simulated snow cover and snow water equivalent (SWE) reflect the detailed geographical features. Due to global warming, the beginning of the snow- accumulating season (the end of the snow-melting season) will occur later (earlier) in most snow regions, and the snow cover will decrease except for very few ex- ceptions. SWE will also decrease in wide areas, but over the cold regions (Siberia and the northern parts of North America), SWE will increase due to increases of snowfall in the coldest season. In both the change and the percentage change of the SWE, we can find that the detailed geographical features effect on them. In Japan, the SWE will decrease over the heavy snow areas. However, the percentage changes are relatively smaller over the colder areas.