【作者】 李奇虎；

【导师】 陈亚宁；

【作者基本信息】 华东师范大学 ， 地图学与地理信息系统， 2012， 博士

【摘要】 气候变化是一个国际热点问题,气温升高已经是不争的事实,但同时也有区域差异性。长时间序列的气象数据研究,可以揭示区域气候变化的特征、变化机理以及预测未来的气候变化趋势。西北干旱区生态敏感,由于其年降水量低,日照时数长以及蒸发量大等特点,已被众多学者所关注,同时由于其独特的地理位置,决定了其对全球气候变化有很好的响应,并影响着全球的气候变化。本文利用近半个世纪的日气温、降水及径流数据,结合时间分辨率最高的MODIS日积雪面积数据,对西北干旱区气候变化及水文过程进行研究,结果表明：(1)近50a来,西北干旱区气候变化的总体趋势是由暖干向暖湿变化,气温、降水的年际倾斜率分别为0.37℃/10a,6.5mm/10a,而且气温上升的趋势更加明显；气温变化的特点为：纬度越高,升温越快；高程越高,升温越快,且纬度影响更大一些。在西北干旱区具体表现为天山以北区域增温速度要高于天山以南区域,高山区比平原区增加要显著；通过Hurst指数分析表明,当前气候变化趋势具有延续性,在四个典型流域(阿克苏河、叶尔羌河、和田河和开都河),气温的变化趋势一致,均在1996年发生突变,而降水变化只在阿克苏河和开都河流域呈现增加态势,而叶尔羌河和和田河流域的降水变化趋势不明显。(2)用近50年径流时间序列,在流域的尺度上进行分析,发现阿克苏河、开都河径流突变时间分别为1990年和1996年；叶尔羌河径流有增加的趋势,但不显著,和田河流域是唯一的径流减少的河流,进一步借助小波变换和小波方差分析,做周期性判断,发现阿克苏河径流与气温周期一致(18a)；叶尔羌河、和田河径流与降水周期同步(9a)；开都河气温、降水和径流的周期都为18a。这从一个侧面佐证了阿克苏河流域融雪对径流贡献大,而叶尔羌河与和田河对降水的敏感性更强,开都河流域径流增加是气温升高和降水增加共同作用的结果。(3)近50年以来,西北干旱区的极端气温变化中,冷指数在减小,而热指数则呈现增加态势,冷指数趋势更为显著；且2000年以后气温的变率明显加快,极端气温变化的频率也更为稳定；西北干旱区的湿日数显著减少,但降水总量增加明显。湿日数减少主要是由于0.1～6mm强度的降水日数锐减引发。强降水对西北干旱区降水总量贡献很大,降水总量的增加很大程度上是由12-24m1m和6-12mm的强度降水的显著增加引起的。径流极值对极端气温、降水变化很敏感,短时洪峰次数有增加的趋势,且阿克苏河流域是极端气温变化引起,而在叶尔羌河是极端降水波动的结果；和田河流域和开都河流域的短时洪峰次数有增加,但变化不明显。(4)利用MODIS积雪产品分析,塔里木河流域的高山区在2-4月、8-10月积雪面积有增加趋势,5-8月、10-翌年1月积雪面积减少；夏季雪线在天山南坡是4200米左右,而在昆仑山北坡则在5800米附近；最后,通过10日合成积雪面积数据与降水、径流数据曲线的对比发现,汛期径流的洪峰,是雪线(天山南坡4200米,昆仑山北坡5800米)以下的积雪面积减少和降水量增加共同作用的结果；而雪线以上的积雪,其产生的水量主要是渗透到冻土或是山间裂隙中,维持了枯水期径流的流量。更多还原

【Abstract】 Climate change has been a global issue and it has been proved true that the temperature is increasing with regional variations. The study of long time meteorological data series can guide the study of character, mechanism and the evaluation of the future climate. The arid region of China is characterized by low precipitation, long duration of sunshine and strong evaporation, making this area an ecological fragile region and has long been concerned. Meanwhile it is influenced by the global climate change due to its special location and in turn affects the global climate change.In this article, the daily temperature and precipitation data along with the hydrological data was analyzed, in conjunction with the snow cover area charts from the MODIS satellites (MOD1OAl) in order to study the climate change and hydrology in the arid area in the northwest China.The research results indicate that:(1) The arid region of northwest China has gone through from warm-dry condition to warm-wet condition in the past50yr, and the changing rates of temperature and precipitation are0.37℃/10a,6.5mm/10a. In addition, the change of temperature is much more significant than precipitation. The spatial character of temperature change can be summed up as the higher the latitude is, the higher the elevation is, the faster the increasing is, and further the former has greater influence. In the study area, the northern area of Tianshan Mountain has seen the faster increase of temperature than the southern part and the mountainous area has a more intense increase than the plain area. The current climate change tendency will be continuous in the future based on the Hurst index. The temperature change tendencies are alike in the four typical basins and the temperature catastrophe points happened in1996. Only Aksu River and Kaidu River show increasing trends in precipitation and Yarkand River and Hotan River show no changing tendency.(2) By studying the runoff changing characters of the headrivers, the catastrophe points of runoffs of Aksu River and Kaidu River happened in1990and1996. the runoff of Yarkand River increased, but the tendency does not significant, and Hotan River turns out to be the only river that has a decreased runoff.Periodic analysis by using the wavelet transform and wavelet variances analysis confirms that the melting water in the Aksu River basin contributes a lot to the runoff in another side. The results also manifest that the runoffs of Yarkand River and Hotan River are more sensitive to precipitation while the increased runoff of Kaidu River is the combined impact of increasing temperature and precipitation.(3) Most of the cold indexes are in downward tendencies while the warm indexes in upward tendencies as a whole in the past50years. In addition, rate of change of the extreme temperature after2000is higher than before and its frequency is becoming stable.Number of wet days is decreasing significantly while the annual precipitation is increasing evidently in the arid area of northwest China. The decrease is mainly caused by the sharp decrease of days of0.1～6mm precipitation. The heavy precipitation contributes a lot to the annual precipitation, especially the heavy precipitation intensity between12-24mm and between6-12mm.The extremes of runoff were sensitive to the changes of extreme temperature and precipitation. Times of short term flood peak increased, and it was caused by the change of extreme temperature in Aksu River basin, but it is due to the fluctuation of extreme precipitation in the Yarkand River. That change was not significant in Hotan River and Kaidu River.(4) The snow-cover area shows an increasing tendency during February to April and August to October and a decreasing tendency from May to August and from October to the following January using the MODIS data in the mountainous regions in the Tarim River basin. The snow line of the southern slope of the Tianshan Mountain is4200m, while the height reaches5800m in the northern slope of Kunlun mountain. Contrastive analysis of the10-days combined snow cover extent charts and the precipitation and runoff data manifests that flood peak is caused by the combined action of snow melting below the snow line (for the southern slope of Tianshan mountain, the elevation is4200m; the northern slope of Kunlun Mountain, it is5800m) and the precipitation increasing; while, above the snow line, the melt water is mainly used for recharging the groundwater and in turn maintain the runoff in the dry season.更多还原