摘要
利用中国西北地区135个测站1961-2009年历年逐日地面最低气温和NCEP/NCAR再分析资料,采用线性趋势分析、Mann-Kendall分析、子波分析、功率谱分析和合成分析等方法,分析了近49年中国西北地区极端低温事件的演变特征。结果表明:(1)西北地区极端低温的低值主要出现在北疆和青海高原,这些地方的阈值在-20℃以下;(2)西北地区年极端低温频率以-3.7d.(10a)-1的速率显著下降,大多数地方则以3～5d.(10a)-1的速率显著下降,突变出现在1985年,低温频数有显著的3年周期。(3)西北地区极端最低气温介于-49.8～-8.6℃之间,最低值出现在新疆的富蕴。低温强度与极端低温在地域上有相同的分布,极端低温越强,持续的日数就越多;极端低温频发的时段也是低温最强的时段,气候变暖导致极端低温事件减少,强度减弱。(4)环流特征量分析表明,新疆极端低温与纬向环流、极涡特征量和大西洋欧洲环流型有关,而其余地方主要与副热带高压和青藏高原高度场有关。合成分析表明,极涡偏于东半球,极区为正距平,中纬度为带状负距平,新疆脊偏西,东亚大槽深厚,中国西北地区处于新疆脊前,西北气流强,易出现低温天气;乌拉尔山低槽、新疆脊和东亚大槽中高层位置稳定,大气为准正压状态,在新疆脊控制下,西北地区不利于产生大范围持续性低温天气。
The low temperature events were analyzed based on the NCEP/NCAR data and the daily minimum temperature observation data from 135 meteorological stations in the Northwest China during 1961-2009,using the methods of linear regression analysis,Mann-Kendall,running T-test,wavelet analysis,power spectrum and composite analysis.The results show that：（1） The spatial distribution of the extreme minimum temperature in Northwest China presents the distributed tendencies of two high and low interactions.The areas with minimum temperature value are located in northern Xinjiang and Qinghai Plateau.And the threshold value of extreme minimum temperature in these places are below-20 ℃;（2） The frequency of annual extreme minimum temperature has obviously reducing at a rate of 3.7 d·（10 a）-1,majority places remarkably reduced at a rate of 3~5 d·（10 a）-1.There is an abrupt change in 1985,the minimum temperature frequency has the remarkable 3 year periods.（3） The values of extreme minimum temperature are between-49.8 to-8.6 ℃,the maximum value appears in Fuyun of Xinjiang.There is a same geographic distribution between minimum temperature intensity and extreme minimum temperature. The intenser the extreme minimum temperature is,the longer the day number of duration is. The phase of frequently occurring of minimum temperature is also the phase of the strongest minimum temperature.The global warming causes the extreme minimum temperature events reducing and intensity weakening.（4） From the circulation characteristic quantity analysis, the extreme minimum temperature in Xinjiang related with zonal circulation,polar vortex characteristic quantity and Atlantic-Europe circulation,but the extreme minimum temperature in other places related with subtropical high and QinghaiXizang Plateau height field.The composited analysis indicated that the polar vorticity center is located the Eastern Hemisphere.The Arctic region is the positive anomalous.The middle latitude is belt-shaped negative anomaly.Xinjiang high ridge is located to the west.The East Asian trough is deep.The northwest arid area is in front of the Xinjiang high ridge.The northwest air current is easy to appear the minimum temperature weather. The positions of Ural mountain minimum trough,Xinjiang high ridge and East Asia big trough from 500 hPa to high-level are stable.The atmosphere is the quasi-barotropic state,Northwest China region is controlled by the Xinjiang high pressure ridge,which is unfavourable to the wide range and duration minimum temperature weather.
出处
《高原气象》
CSCD
北大核心
2011年第5期1266-1273,共8页
Plateau Meteorology
基金
国家自然科学基金项目(40975054)资助
关键词
西北地区
极端低温
气候变化
Northwest China
Extreme minimum temperature
Climatic change
