Temperature changes before and after precipitation in Mongolia

抄録

Drastic temperature decreases after precipitation events in the cold season in Mongolia can harm livestock, often leading to high stock mortality. We investigated seasonal and regional temperature changes before and after precipitation in Mongolia. We conducted a time-series analysis of changes of temperature relative to daily mean temperature at 25 weather stations before, on, and after days of precipitation. We categorized the relative temperature time series into three types: peak shaped (P), valley shaped (V), and gradually decreasing (D), which characterized spring-summer, winter, and autumn, respectively. We produced 11-day time series of relative temperature centered on precipitation days for each precipitation event at each station from 1961 to 2007 and applied principal component analysis to the relative temperature time series. Our results show that the first principle component (PC1) pattern is V-shaped, and the principal component analysis scores tended to be negative in winter and positive in spring. The PC2 pattern was closely related to the D-shaped trend of relative temperature, and the scores were positive from autumn to early winter and negative from spring to summer. Synoptic weather pattern analysis before and after precipitation days showed that, in general, both the P- and V-shaped trends accompanied the passage of a cold front; whether were patterns are P- or V-shaped was determined by the thermal conditions of the background air mass into which the contrasting air mass invaded to produce a precipitation-bearing front.