内蒙古地区近四十年极端天气气候事件变化研究

Study of Extreme Daily Temperature and Precipitation in Recent Forty Years of Inner Mongolia

内蒙古地区作为对全球气候变化敏感的典型区域,在全球暖化背景下,了解和掌握该区域极端气候频发的原因及特定的周期性规律,对于制定草原区资源可持续利用战略具有极其重要的现实意义.利用1970-2012年的49个气象站点数据对内蒙古地区近四十年极端气候事件进行了研究,结果表明:极端高温在2000年之前波动性较小,之后呈大幅增温趋势,在呼伦贝尔草原区和森林区增加幅度较大;极端低温则在2000年前增幅较大,之后波动性较大,极端低温的增幅要大于极端高温;霜冻日数(Fd0)呈显著减少趋势;结冰日数(Ido)在2000年前显著降低,之后显著增加,炎热夜数(Tr20)和夏季日数(Su25)则是显著增加,Fd0、Id0、Tr20和Su25在空间格局上的变化是一致的;有效积温显著增加.年总降水量、降水强度、大雨日数都在20世纪90年代有略微增加,近十几年的值均低于平均水平,单日最大降水量在20世纪80、90年代大于其平均水平,说明极端降水事件有增大趋势,与极端温度相比,极端降水指数的空间分布一致性较差,在草原区和东北部森林区普遍减少,而在荒漠区普遍增加.

Since Inner Mongolia is a typical sensitive region to global climate changing, study on the reason and periodicities of the extreme climate events and their frequency in this region will be very important for developing a sustainable resource use strategies for the grassland under the background of global warming. In current study, the data of 49 meteorological stations during 1970 2012 were collected to analyses the extreme climate events in this forty years. The results showed that,the maximum temperature （Txx） had small fluctuation before 2000 but increased dramatically after that, especially in the forest and steppe in Hulun Buir region. The minimum temperature （Tnn） increased a lot before 2000 then had a big fluctuation. At the same time,the increasing level of Tnn frequency was significant higher than Txx. Significant decreasing of annual frost days were detected, along with a decreasing of annual ice days before 2000. Meanwhile,annual tropical days and summer days were increased significantly. These trends in extreme temperatures show a considera- ble consistency across the region. The effective accumulated temperature （EAT） also displayed a significant increased trend. The annual precipitation （Prep）, extreme precipitation intensity （SDII） and the days of rain （r20） had a slight increase in 1990s but the numbers in the past decade was be low the average line. The 1-day extreme rainfall in 1980s and 1990s were higher than average line, indicates the frequency of extreme rainfall events had an increase trend. Compared to the extreme temperature,the Prcp,SDII and the r20 showed a decreasing trend in forest and steppe but an increasing in the desert region.