沈阳近百年的温度变化特征及其环流形势分析

SHENYANG TEMPERATURE CHANGE CHARACTERISTIC AND ITS CIRCULATION SITUATION ANALYSIS OF THE PAST ONE HUNDRED YEARS

沈阳地处全球温度变化的敏感带 ,在近百年的温度观测记录中 ,沈阳的温度变化呈逐渐上升之势 ,近百年增高约 1.7℃ ,这种上升趋势在冬季远比夏季明显。沈阳的年平均温度变化有一个 12a的周期 ,各周期温度基本呈阶梯状上升 ,2 0世纪末的周期冬季平均温度比世纪初的周期升温 2 .8℃左右。从近 5 0a的极端温度的变化趋势来看 ,极端最低温度明显升高 ,而极端最高温度并没有上升 ,变化趋势甚至略下降 ,以致冬、夏两季温差缩小。从沈阳的最低平均温度和最高平均温度变化来看 ,两者均随时间逐渐升高 ,说明沈阳市的增温不仅是最低温度升高造成的 ,最高温度的增温作用亦十分重要。从冬季环流形势分析来看 ,东亚大槽及其后弱脊和地面蒙古高压在上世纪 80年代、90年代明显减弱 ,使得冷空气向南侵袭的径向气流减弱 。

Shenyang locates in the sensitive region of global change. In past one hundred years, Shenyang temperature kept rising gradually by 1.7 Celsius degrees. This trend is more obvious in winter than in summer. Annual average temperature of Shenyang has a 12-years cycle, and temperature basically presents ladder form rise in every cycle. The cycle average temperature in winter of the end of 20th century rose about 2.8 Celsius degrees than that of the beginning of the century. According to variation tendency of the extreme temperature of the past 50 years, the minimum extreme temperature obviously rose; the maximum extreme temperature has not risen, but slightly dropped, so that the temperature difference reduced between winter and summer. The fact, the lowest average temperature and the highest average temperature of Shenyang both rise gradually with time, proves that not only the rise of minimum temperature leads to the increasing warm of Shenyang, but also the rise of maximum temperature is also important. Analysis of the winter circulation situation shows that: East Asia Trough, the weak ridge behind it, and Mongolian Ground High subsided obviously after the 80s of last century, and the cold air current passed Shenyang from the north is weakened consequently. This is one of reasons why Shenyang temperature is obviously increasing in winter.