横断山区干旱河谷气候变化趋势研究

Trend of the Climate Changes in Dry Valleys of Hengduan Mountains,China

利用横断山区干旱河谷内20个典型气象台站的长时序逐月气温、降水、相对湿度、日照时间、极端最高气温和极端最低气温等数据,采用线性倾向估计、Mann-Kendall趋势检验以及集中度和集中期等分析方法,研究了横断山区干旱河谷的气候变化趋势。结果表明:(1)全球变化背景下,横断山区干旱河谷平均气温总体呈现升高趋势,升幅为0.11℃·(10 a)-1,较整个横断山区的0.15℃·(10 a)-1略低,冬季升温幅度高于其他季节;(2)金沙江下游的元谋、东川和巧家段河谷呈现持续降温趋势,特别是春季降温较为明显;(3)横断山区干旱河谷降水量呈微弱减少趋势,为-1.48 mm·(10 a)-1,这主要是由于夏季降水减少量超过其他季节降水增加量所致;(4)多数河谷站点年降水量的集中度呈微弱下降趋势,而集中期则有所提前,但不明显;(5)干旱河谷相对湿度和日照时间在近几十年间均呈现减少趋势,相对湿度每10 a约减少0.16百分点,而日照时间则平均每10 a减少24.26 h。

A long period of meteorological data collected at 20 typical meteorological observation stations scattered in dry valleys of the Hengduan Mountains,including monthly air temperature,precipitation,relative humidity,sunshine hours,highest air temperature and lowest air temperature,were cited for analysis of trend of the climate changes in the region,using the linear tendency estimation,Mann-Kendall test,precipitation concentration degree （PCD） and precipitation concentration period （PCP） methods.Results show that （1） affected by the global climate change,the mean air temperature in the dry valleys presented generally a rising trend with a rate of 0.11 ℃ · （10 a）-1,a bit lower than the rate [0.15 ℃ · （10 a）-1] of the whole Hengduan Mountains and it was more obvious in winter than in other seasons; （2） the mean air temperature in Yuanmou,Dongchuan and Qiaojia Valleys in the downstreams of the Jinsha River displayed a declining trend,more obvious in spring; （3） the precipitation in the dry valleys dropped slightly,by 1.48 mm· （10 a）-1,which is mainly attributed to the reduction of precipitation in summer,which was more obvious than that in other seasons; （4） annual precipitation in most of the dry valleys weakened in PCD,but temporally advanced in PCP,though not so obvious; and （5） relative humidity and sunshine hours presented a declining trend in recent decades.The former decreased at a rate of 0.16% · （10 a）-1 and the latter at a rate of 24.26 h · （10 a）-1.