东北地区近40年干燥指数变化趋势及其气候敏感性

Long-term trends of aridity index and its sensitivity to climate factors in Northeast China:1971-2008

基于东北地区91个站点1971～2008的常规气象资料,应用Mann-Kendall方法分析了区内近40年干燥指数的变化趋势,并基于Penman-Monteith公式计算了干燥指数对各气象要素的敏感性系数,分析了气候变化影响下,干燥指数气候敏感系数的变化规律。研究表明:(1)东北地区近40年来干燥指数以0.06/10a的趋势增加,2000年以来为近40年最干燥的时期;(2)东北地区干燥指数对实际水汽压的敏感性仅次于降水,而对平均风速的敏感系数最小;(3)干燥指数对气温变化的敏感性由北向南增加,对水汽压变化的响应以东部地区最为强烈,对太阳辐射变化的敏感响应区域为长白山山麓一带,而对风速变化响应较为敏感的区域则为东北大平原的西部和大兴安岭的南段;(4)近40年来东北地区干燥指数对于气温、风速以及太阳辐射敏感程度呈增加趋势,而对水汽压的敏感程度明显减弱。气温升高和降水减少是东北地区干燥程度加深的主要原因,但水汽压的增加、太阳辐射的减少和风速的减少缓解了这一趋势。

Northeast China plays an important role in food production and ecological conservation in China.Changes of wetness accompanying with global climate change could have significant impacts on food security and ecosystem health in the area.In this paper,the long-term trends of the aridity index are detected using Mann-Kendall approach for the period 1971-2008.The results of the trend test show that there was an insignificant increase of the aridity index in the region.To explore the cause of the trend,the sensitivity coefficients of aridity index in relation to climate factors including precipitation,temperature,vapor pressure,solar radiation and wind speed were calculated based on the Penman-Monteith method.It is shown that the coefficients related to actual vapor pressure were only slightly lower than those of precipitation,followed by those of temperature,solar radiation and wind speed.The sensitivity of aridity index to temperature decreased from south to north of Northeast China,while that for vapor pressure and solar radiation was largest in the eastern part of the region and the Changbai Mountains respectively.Under the impacts of climate change,the sensitivity coefficients related to temperature,wind speed and solar radiation increased,while the coefficient related to actual vapor pressure decreased.During the past 40 years,the increasing temperature and decreasing precipitation were the main reasons for increased aridity index,but increased vapor pressure,decreased solar radiation and wind speed had alleviated the increase of drought risk in the region.