【作者】 王欢；

【导师】 李栋梁；

【作者基本信息】 南京信息工程大学 ， 气象学， 2014， 硕士

【摘要】 本文采用黄河源区唐乃亥水文站实测逐月流量、源区8站气候资料,以及NOAA植被指数和欧洲中心环流场资料,运用线性趋势分析、回归分析及贡献率、边界水汽计算等方法,分析了近60a黄河源区流量变化特征,并在此基础上研究了气候因子变化对流量的贡献,进而分析高原夏季风、感热通量对源区边界水汽、温度、流量的影响,最后给出气候因子影响流量单、双峰型变化的概念模型,并得到了以下主要结论：1)近60a黄河源区流量呈现2个线性上升时段(1956～1967年、2002～2012年)、1个线性下降时段(1989～2002年)和1个振荡调整时段(1967～1989年),且在流量的上升阶段,其周期变化由8a的长周期转变为2～4a的短周期。2)流量变差系数Cv最大的是80年代,对应流量年内分配呈现7、9月双峰型,变差系数Cv最小的是50年代和90年代,流量年内分配呈现7月单峰型。秋季流量的增加使得流量年内分配出现第二个峰值点,秋季流量决定了年流量距平。3)在平水年流量年内分配主要是单峰型,而在偏丰和丰水年则以7、9月和7、10月双峰型为主,在偏枯和枯水年虽然也以双峰型为主,但是峰值点出现的月份比较随机,且峰值点的流量值也较小。4)近年来黄河源区气候逐渐趋于暖湿。降水量在21世纪以后呈现明显的上升趋势,且在上升阶段降水量也存在2a左右的显著短周期,而源区南部和中部是全区降水量大值集中区,降水量的年内分布形式与流量相对应,主要有7月单峰和7、9双峰双峰两种主要类型。源区温度、蒸发不论是时间上还是空间上都呈现上升趋势,气候倾向率分别为0.4℃/l0a和6.78mm/10a；源区温度、蒸发的年内分配形式为典型的单峰型,峰值点主要出现在7月,且二者之间有较好的同步和一个月的滞后相关性。黄河源区植被不论是时间上还是空间上,从20世纪80年代到21世纪都呈现一个恢复的趋势；源区植被的年内分布从80年代和90年代的8月单峰型转变为21世纪的7月单峰型。5)降水对流量的正贡献呈现逐年增大趋势,温度对流量的贡献则由正贡献逐渐转变为显著的负贡献；而植被对于流量的贡献则比降水和温度小一个量级。降水对流量年内变化的贡献呈现7、9月双峰型,温度对于流量年内变化为9月单谷型负贡献,二者相互作用造成流量多年平均7、9月双峰型。6)当黄河源区附近地面感热通量增加,而周围感热通量减少时,对应源区地面给大气的加热增强,其周围加热减少,引起源区大气上升运动加强,源区上空600hPa位势高度场降低,有利于黄河源区水汽辐合上升,同时高原热低压(高原夏季风)强度的加强,源区气候暖湿化,夏、秋季流量增加,形成流量年内分配的峰值点；当高原夏季风位置偏北时,黄河源区南边界输入水汽增加,东边界输出水汽减少,造成源区上空水汽通量增加,区域降水增加,流量增加,形成流量年内分配双峰型。更多还原

【Abstract】 Based on1956～2012monthly runoff data of Tangnag and climate data of8stations in Source Region of the Yellow River, also with NDVI and circulation field data from NOAA and ERA. Through trend analysis, calculated contribution of climate factor and boundary vapor transportation, analyzed the characteristics of the runoff in Source Region of the Yellow River for recent nearly60years. On the basis of the contribution of climate factors’ change to the runoff, than analyzed the influence of plateau summer monsoon and the surface sensible heat flux to boundary vapor, temperature and runoff. At last the conceptual models of the cause for bimodal pattern is given, also obtained the main conclusions are as following:1)There are2linear rise(1957-9167,2002-2012) periods,1linear decline period and1oscillation period of the variation of the runoff.During the rise periods, the periodicity of the runoff turned to2-4years from8years.2)The maximum coefficient of variation appeared in80’s,accordingly, the annual contribution the runoff take on bimodal. The minimum coefficient of variation appeared in50’s and90’s, the peak value is the least in the between several decades.3)The annual contribution of the runoff mainly have two types,one is the unimodal of July,anther is the bimodal of July and September. In normal years, the annual contribution mainly is unimodal type, in the high flow year, the annual contribution mainly is bimodal,in the low flow year, the annual contribution also is bimodal, but the peak value appears random.4)The climat became warm and wet. The precipitation takes on increase in the21st century. The precipitation in the south and middle region in Source Region of the Yellow River is stronger than other parts. The annual contribution of the precipitation mainly have two types,one is unimodal of July,another is bimodal of July and September The temperature and evaporation in Source Region of the Yellow River take on uptrend.The annual contribution of the temperature and evaporation are unimodal, the peak value appears on July. The vegetation in Source Region of the Yellow River takes on recover tendency from1980’s to21st century both in time and space. The annual contribution of vegetation is unimodal of August in1980’s and1990’s, and it turned into unimodal of July in21st century.5)The positive contribution of precipitation to runoff takes on rising trend, meanwhile, the contribution of the temperature turned from weak positive to notable negative. The precipitation contribution to the runoff annual distribution is bimodal, the peak value appears on July and September, also the temperature take on unimodal, the peak value appears on September, the precipitation and temperature work together, makes the annual runoff distribution takes on bimodal of July and September.6)When the surface sensible heat flux in Source Region of the Yellow River increase, the heat of atmospheric to the ground is enhanced, so makes the geopotential height field over the Source Region of the Yellow River decrease, the evaporation convergence and updraft. At the same time, the strengthen of the summer plateau monsoon makes the climate warm and wet, the Autumn runoff increase. And the position of the summer plateau monsoon just north, makes the input vapor of north boundary increase, the output vapor of east boundary decrease, caused precipitation increase, so the runoff increase, form the bimodal pattern.更多还原