近43年来“三江源”地区气候变化趋势及其突变研究

利用“三江源”地区14个气象台站1962-2004年气温、降水量资料,分析了该地区气候变化趋势及其突变情况。研究表明:近43年来,“三江源”地区气温普遍升高,年及夏、秋季降水量的变化呈微弱减少趋势,而冬、春季降水量呈现出显著增加趋势,气候暖湿变化表现出不同季性,四季及年蒸发量变化呈逐年增大趋势;气候变化具有显著的区域性差异;年平均气温在1987年出现了由冷到暖的突变,冬、春季降水量均在20世纪70年代中期和80年代出现了由少向多的突变,年蒸发量在1986-1988年间发生由少到多突变。全球升温并由此引起的海洋蒸发和陆地上的蒸散加强,地气水分循环加快,是“三江源”地区气候出现暖湿变化的主要原因。

Study on the Climate Change Trend and Its Catastrophe over "Sanjiangyuan" Region in Recent 43 Years

Using air temperature and precipitation data in 1962-2004 of 14 meteorological stations over "Sanjiangyuan"(head waters of three rivers) region,the changing trend of climate factors and its abrupt changes in evaporation and precipitation as well as air temperature are analyzed.The results show that the seasonal mean air temperature and annual mean over "Sanjiangyuan" region has been rising in recent 43 years,the rising of annual mean air tempera-ture is caused by the rising mean air temperature in summer and autumn;the variation of precipitation in a year,summer and autumn has been slightly decreasing,while the precipitation in winter,and spring has been increasing,and the warming and wet variation is featured in different seasons;the annual and seasonal variations of evaporation have been increasing under the condition of air temperature's rising,and precipitation is regarded as the main material resource of evaporation.Its variation trend,to some extents,causes the variation characteristics of evaporation.The climate change shows significant regional difference,the orographic factor of latitude,longitude and sea level has a significant influence upon the climate change,and annual mean temperature presented abrupt change in 1987 which is consistent with air temperature over the northwest region,but the abrupt change occurred earlier than that in northern hemisphere.The precipitation in winter and spring presented an increasing trend in the 1980s and the mid 1970s,and abrupt change in annual evaporation appeared in 1986-1988.Due to global warming,the evapotranspiration on land surface and evaporation on ocean has been increasing;as a result,the water-vapour cycle was accelerated,which is the main cause of warming/wet variation over the "Sanjiangyuan" region.