【摘要】 选取1981年7月-2006年12月美国国家海洋和大气局(NOAA)系列卫星观测的归一化植被指数(NDVI)资料和Ch-INDV参数化关系式,计算了我国西北干旱区84个测站历年各月的地表热力输送系数Ch值和地面感热通量序列,得到如下主要结论:(1)西北干旱区地面感热通量实际计算值与ERA-40再分析感热资料相比,两者在数值大小、分布形势和年际变化趋势上均较一致,感热实际计算值的空间分布更明显地突出了各气象站所在区域的局地特征。(2)西北干旱区地面感热输送呈单峰型年变化特征,春、夏季非常强,秋、冬季较弱;大部分区域全年均为正值,地表为感热源。(3)以97.5°E为界,西北干旱区东、西部具有不同的年际变化趋势,东部的地面感热四季均有逐年增加的趋势,而西部秋、冬季逐年略有增加,春、夏季逐年减弱明显,气候倾向率分别为-1.15 W.m-2.(10a)-1和-2.08W.m-2.(10a)-1。(4)西北干旱区地面感热输送具有明显的年代际变化特征,1980年代总体偏强,1990年代总体偏弱,2000年以来,西北地区中部的感热输送偏弱,东、西部除个别测站外均偏强。(5)西北干旱区的感热变化并不只由地气温差的变化来决定,它与地面风速和地表状况的变化也有较强的依赖关系。在冬季,主要响应地气温差的变化,春季地面风速和地气温差的影响作用同等重要,夏季以地面风速的影响为主,地气温差的影响次之,秋季与夏季相反。另外,夏季地表状况对感热的影响作用也不容忽视。更多还原

【Abstract】 The monthly surface thermal transfer coefficients at 84 meteorological stations in the arid region of northwest China are calculated using the normalized difference vegetation index(NDVI) data from July 1981 to December 2006 observed by National Oceanic and Atmospheric Administration(NOAA)remote sensing satellites and Ch-INDV parametric relational expressions,then the monthly surface sensible heat fluxes are calculated by bulk transfer method with the observations of meteorological stations.The obtained conclusions are as follows:(1) The surface sensible heat fluxes calculated by the observation of conventional meteorological station and ERA-40 reanalysis data are uniform on magnitude and in both distribution situation and the interannual change tendency.But the spatial distribution of the calculated values can obviously reveal the local climate characteristics of the surface sensible heat flux in the regions where the weather stations were located.(2)Annual variation characteristic of the surface sensible heat flux appears unimodal change,the surface sensible heat transfer is extremely strong in spring and summer and weak in autumn and winter.The surface sensible heat fluxes in most arid region of northwest China are positive in whole year,so the surface presents as sensible heat source.(3) Taking 97.5°E as the boundary,there are different interannual variation trends in the eastern and western parts of arid region northwest China.The surface sensible heat transfer in the eastern part of the arid region of northwest China increases gradually year by year in four seasons,that in the western part is similar to that of eastern in autumn and winter,but it is contrary in spring and summer and the climate tendency are-1.15 W·m-2·(10 a)-1 and-2.08 W·m-2·(10 a)-1 respectively.(4) The surface sensible heat transfer has an obvious interdecadal change.the surface sensible heat transfer is strong(weak) in 1980s(1990s),that in middle part of arid region of Northwest China is weak since 2000,but strong in its eastern and western parts except for individual stations.(5) The change of surface sensible heat in arid region of northwest China is not only decided by the change of ground-air temperature difference,it also has a close relationship with the changes of ground wind speed and surface condition.In winter,its change is mainly in response to the change of ground and air temperature difference.In spring,the change of ground ground-air temperature difference and surface wind speed play an equally important role.Contrary to autumn,it is prior to the change of surface wind speed and the ground-air temperature difference takes the second place in summer.Furthermore,the influence of surface condition on the sensible heat should not be neglected in summer.更多还原