【作者】 何毅；

【导师】 王飞；

【作者基本信息】 西北农林科技大学 ， 地图学与地理信息系统， 2012， 硕士

【摘要】 气候变化是地球科学目前研究的热点之一，认识气候变化的过程与特征是分析其对资源、环境、经济和生态过程影响的前提。渭河流域地处我国西北黄土高原东南部干旱半干旱地区，生态环境脆弱，旱涝灾害多发，面临许多生态和环境问题。本文基于渭河流域及其周边45个气象站点1951-2009年逐年实测气温、降水量和应用联合国粮食及农业组织（FAO）推荐的Penman-Monteith公式计算的潜在蒸散量，采用趋势分析、空间插值、Mann-Kendall突变检测法、经验函数正交分解、Morlet小波分析、距平累积等方法，研究了渭河流域主要气象要素变化过程、突变点和空间分布特征等，取得如下主要结论：（1）在研究时段内，渭河流域年均气温逐年升高趋势明显。1951-2009年渭河流域的年均气温增温速率0.252℃/10a，年平均最低气温的上升趋势（0.261℃/10a）大于年平均最高气温（0.255℃/10a）。流域内年均温和年平均最低温突变点集中出现在1980s末及1990s初期；而年平均最高温在1994年前后发生突变。采用小波分析方法，分析了流域年平均气温、年平均最高气温和年平均最低气温的周期性，结果表明：渭河流域气温均存在19a、33a，尤以33a周期最为显著。渭河流域年平均气温整体从东向西、从南向北递减的趋势。但不同年代等温线位置有较大变动，根据流域边界和等温线围成的区域面积表征这种变化。年平均气温以多年平均气温9.5℃为阈值，高于9.5℃的区域面积从1960s的34.67%上升至2000年后的69.10%；以最低气温多年平均值3℃为阈值，高于3℃等温线与流域边界围成的面积从1950s的68.55%上升至2000年后的85.75%。气温日较差从1950s至1970s下降，1980s后略微上升，日较差大于11℃区域所占流域总面积比，首先从1950s的55.96%下降至1980s的41.58%，而后又上升至2000年后的61.07%。（2）渭河流域年内降水集中在夏季和秋季，年降水量从1951-2009年有逐年代下降的趋势，气候倾向率是-14.6mm/10a。流域降水量亦发生突变点，在西北部地区多出现在2007年左右，南部地区出现在1970年前后，而在流域西部地区降水量突变点则出现在1986年前后。受大尺度天气系统影响，流域年降水量异常的主要特点是降水量变化的一致性，也存在南北差异和东西差异。渭河流域降雨具有一定的周期性特征。渭河流域年降水量存在存在19a、32a，尤以32a为显著，这与温度变化的周期相一致。采用距平累积方法分析表明降水量具有显著的阶段性特征。主要存在1951-1957年、1993-2002年和2004-2009年大多数站点的降水量均低于多年平均值；1951-1968大多数站点的降水量高于多年平均值；其他时期，降水量围绕多年平均值震荡，特征不明显。（3）在渭河流域全年的潜在蒸散量中，春季和夏季的贡献最大，冬季的潜在蒸散量很小。年潜在蒸散量从1951-2009年有逐年代上升的趋势。潜在蒸散量的气候倾向率为5.08mm/10a。流域潜在蒸散量同样有一定的周期性特征。年潜在蒸散量存在19a、32a，尤以32a为显著，这也与温度变化的周期相一致。采用距平累积方法分析表明潜在蒸散量同样具有显著的阶段性特征。主要存在1951-1968年、1983-1993年大多数站点的潜在蒸散量均低于多年平均值；1969-1982年和1995-2009年大多数站点的潜在蒸散量高于多年平均值。更多还原

【Abstract】 Climate change is not only one of the focuses of earth science researches nowadays, butalso the precondition to analyze regional resources, environment and ecological processwhich are affected by the characteristics and process of climate change. Wei River Basin islocated in southeast of loess plateau of China, where fragile ecological environment leads tohigh occurrence rate of droughts and floods, Wei River Basin is facing many ecological andenvironmental problems. Based on the annual atmospheric temperature, precipitation,monthly climatic data and monthly and yearly potential evapotranspiration of Wei River Basinwith FAO Penman-Monteith Equation of45weather stations around Wei River Basin duringthe period of1951-2009, with the methods of tendency analysis, spatial interpolation,Mann-Kendall method, Empirical Orthogonal Function decomposition, wavelet analysis,traditional statistics and accumulated variance analysis, which can be used to analyze themeteorological elements trend, catastrophe character, spatial distribution characteristics ofWei River Basin and so on. The main conclusions are as follows:(1) The temperature of the Wei River Basin showed an increasing trend between1951and2009. The annual mean temperature was rising at the rate of0.252℃/10a. The rising trendof annual mean minimum temperature (0.261℃/10a) was larger than the annual meanmaximum temperature’s rising rate(0.255℃/10a).The turning points of the mean annual temperature and the mean minimum temperaturewere around the late1980s and early1990s; while the mean annual maximum temperaturewas around1994. With the method of Morlet analysis, the results showed that the periodicityof temperature were about19years,33years, and mainly periodicity was33years.The annual mean temperature decreased from east to west, and from south to north, thatshowed a similar trend. While the position of isotherm changed in different years, base on thearea of region which is encompassed by basin boundary and isotherm. The threshold of themean temperature is9.5℃, which was the mean temperature of the last decades. Theproportion of the area where the average annual temperature was more than9.5℃increasedfrom34.67%in1960s to69.10%after2000,3℃was the threshold of average annual minimum temperatures of the past years. The area of region with the average annualminimum temperatures more than3℃increased from68.55%in1950s to85.75%after2000.Diurnal temperature showed a decreasing trend from1950s to1970s and after1980s whichshowed an slight increasing trend. The proportion of the area where average diurnal range intemperature was more than11℃decreased from55.96%in1950s to41.58%in1980s, thenincreased to61.07%after2000.(2) Most precipitation happened in summer and autumn in a year in Wei River Basin.The precipitation showed a descending trend from1950s to after2000, with the falling rate of14.6mm/10a.The precipitation turning point in northwest regions is located in2007, while theprecipitation turning point in southern region and western region located in1970and1986respectively. The precipitation in Wei River Basin was affected by the large-scale weathersystems. The characteristics of the abnormity of precipitation in Wei River Basin wereconsentaneous, Still, there were different between the south and north, the east and west.Morlet wavelet transmission showed that the periodicity of precipitation were about19years,32years, and mainly periodicity was32years. It was accordance with the periodicity oftemperature change.The analysis on the accumulative anomaly of annual precipitation indicated that Duringthe period of1951to1957,1993to2002, and2004to2009, the precipitation in most stationswas less than the mean value in the past, while from1951to1968, the precipitation in moststations was more than the mean value in the past, and in other times, the precipitationfluctuated around the mean value.(3) The amount of potential evapotranspiration of spring and summer were most, whilethe amount of potential evapotranspiration in winter was less in Wei River Basin. Thepotential evapotranspiration showed an ascending trend from1950s to after2000, thepotential evapotranspiration was rising at the rate of5.08mm/10a. Morlet wavelettransmission showed that the periods for potential evapotranspiration were19years,32years,and the main periods was32years. It was also the same as temperature. The potentialevapotranspiration in most stations was less than the mean value, from1951to1968and1983to1993, the potential evapotranspiration from1969to1982and1995to2009in most stationswas more than the mean value.更多还原