Analysis of Climate Trends in the Altai Mountains Between 1988 and 2012

Abstract:

We investigate climatic change trends in a region of the Altai Mountains located on the western edge of Mongolia using the Weather Research and Forecasting (WRF) model. This region, which lies on the southern border of the Eurasian cryosphere, includes glaciers and discontinuous permafrost areas. Therefore, the region is especially useful for understanding the influence of arctic warming on the mid-latitudes. In addition, the preservation of snow and ice on the mountains is crucial to neighboring communities, especially in Mongolia. Analyses of data for the 25-year period between September 1987 and August 2012 revealed that a decrease in precipitation began to accelerate around the year 2000 regardless of the season. The rate of precipitation decline reached more than 40 mm per year near the mountain ridge where the average annual precipitation was about 500 mm. Moreover, the projected winter temperature has been decreasing annually despite warming in other seasons. Further analysis that focused on winter temperature variation found that the hemispheric atmospheric circulation was fluctuating. This slows the zonal wind speed, decreases the temperature by permitting southing of cold air, and decreases precipitation by restraining the inflow of water vapor. Water vapor reduction also contributes to temperature decline through the radiation cooling effect. Extreme cold winter weather events in Eurasia have been reported with increasing frequency in recent years. In this region, winter temperatures are declining continuously while desiccation is spreading simultaneously.