【作者】 李巧媛；

【导师】 谢自楚；

【作者基本信息】 湖南师范大学 ， 自然地理学， 2011， 博士

【摘要】 论文主要是围绕不同气候变化情景下青藏高原冰川的变化这一主题进行的理论研究,在对青藏高原自然地理环境特征、青藏高原冰川特征以及青藏高原近期气候变化特征进行研究的基础上,利用冰川系统模型对升温情景及降温情景下青藏高原冰川的变化进行了研究。本研究的主要结论有如下几点：(1)青藏高原的冰川总计有36924条,冰川总面积达50657km2,冰川总储量为4680.5km3,依次占中国西部现代冰川的79.6%、85.2%和83.6%。冰川系统中规模大的冰川对整个冰川系统的规模影响比规模小的冰川大。青藏高原冰川平衡线具有两大特征：一是整个高原平衡线变化的总趋势是东南向西北方向逐渐升高,在高原西北形成闭合区,呈同心圆状；二是平衡线的变化梯度存在明显的区域差异,高原边缘的平衡线变化梯度较大,高原中心的平衡线变化梯度较小。青藏高原冰川分布的特征受其独特的自然地理环境的控制和影响非常明显。(2)青藏高原年平均气温整体呈上升趋势,约以0.35℃/10a的速度上升,其中冬季升温比夏季明显,高原气温在1990年以后以较快的速度上升；海拔较低、气温偏高的区域气温变化较慢。青藏高原降水呈增加趋势,平均增速为9.2mm/10a。青藏高原除夏季降水变化趋势不明显外,其他季节降水都呈增加趋势,其中冬季降水增加速率最快,达17.6mm/10a。青藏高原年降水变化周期也随时间而变化,1980年前主要有6a、22a两个周期,1980年后这两个周期合并发展为11a周期。相对湿度也有弱增加的趋势,不过不如气温、降水的变化趋势明显。(3)气候变暖情景下,青藏高原冰川表现为不断退缩并最终可能消亡的变化趋势,但其变化速度受到气温变化速率的直接影响。若青藏高原气温、降水保持现有的变化速率不变,到21世纪末,青藏高原的冰川将比1980年时退缩2/3,其储量将减少3/4。不同冰川系统对气候变化响应的敏感性是不同的,在同样的气温变化情景下敏感的冰川系统的敏感性总是较高的,反之亦然。冰川规模越小,对气温升高的敏感性越高。气温的不断升高会在冰川变化的开始阶段带来较多的冰川融水,但之后将持续减少,同时使冰川融水量的变率增大,这对受其影响较大的区域的水资源利用极为不利。(4)降温情景下,冰川的面积有增大的趋势；不同的降温速率对冰川系统变化的影响比较明显,对冰川面积变化过程和冰川融水径流量变化过程都有明显的影响；降温情景下冰川系统产生的融水径流量变化比较复杂,先减少,在短期增加之后又持续减少,不同降温速率下冰川融水径流量的变化曲线过程相差较大。(5)在不同气候情景下,青藏高原冰川融水径流量的变化都有先增加后减少的特征,但二者在面积变化上的特征完全不一致,升温情景下冰川面积将逐渐减少直到完全消失,降温情景下冰川面积则将逐渐增大。冰川对气温变化的敏感性差异与气温变化方向无关,即不论是升温还是降温,只要是在相同的变化背景下,冰川对气候变化响应的相对敏感性不变,即对升温响应敏感性强的冰川对降温的响应也较敏感,反之都不敏感。更多还原

【Abstract】 The study is about the glacier variation under different climate change scenarios of Tibetan Plateau. Based the introduction of the nature geogrphice characteristic of Tibetan Plateau, the analysis on the characteristics of the Tibetan Plateau glacier system and the feature analysis of the recent climate variation of Tibetan Plateau, the glacier variation features under different climate change scenarios are discussed on the glacier system model. There are two basic climate change scenarios of the climate change, which include temperature rising and temperature decreasing. Its obtained some standpoints followed.First, there are 36924 glaciers scatters around Tibetan Plateau, which total area is 50657 square kilometers and its total volumn is 4680.5 club kilometers. The ratio of the Tibetan Plateau glacier to China glacier is 79.6%,85.2% and 83.6%, in sequence. The big glacier influences the scale of glacier system more obvious than the small one. There are two great features about the equilibrium-line altitude distribution of Tibetan Plateau. One is the equilibrium-line altitude lifts gradually form the Southeast to the Northwest, and there is close center in the Northwest Tibetan Plateau. Another one is the gradient of the equilibrium-line altitude change is high at the rim of the Tibetan Plateau, while it is smaller at the center of the Plateau. As a whole, the features of the glacier distribution of Tibetan Plateau are influenced by the unique nature geographic condition of the huge mid-latitude plateau of Tibetan Plateau obviously.Second, the temperature of Tibetan plateau is rising and the velocity is about 0.35℃/10a generally. The winter average temperature is rising quite rapid than the summer average temperature. At the same time, the temperature of the high altitude regions increased more quick than the low altitude regions. The velocity of the temperature rising seems enhanced in the last decadal. The annual precipitation increased in the rate about 9.2mm/10a of Tibetan Plateau. In Tibetan Plateau, except of the summer, the average precipitation increases gradually in the other three seasons, while the highest increasing rate is 17.6mm/10a, in winter. The precipitation variation cycle of Tibetan Plateau is changed about 1980y, the two cycles (6a and 22a) insteaded by the lla cycle around the time hinge. The relative humidity of the Tibetan Plateau increased weakly, also.Third, under climate warming scenarios, the glaciers of the Tibetan Plateau shrink continually and die out eventually in generally. The velocity of the temperature rising effects the glacier variation speed significantly. Take as it is stable climate change states in the future, the glacier area of Tibetan Plateau will shrink to about the one of three of thel980’s in the end of the 21st century. And the volumn of the glacier of the Tibetan Plateau will be about one of four of the level of 1980’s state. The sensitivity of every glacier system is relatively conservative in the response to the climate change, that is, the sensitive glacier system will be more sensitive than the stable glacier system under the same climate change background always. Furthermore, the small glacier is more sensitive to the temperature rising than the big glacier. The continually temperature rising brings with the increase of the glacier melt water at the beginning period of the glacier shrinkage of the Tibetan Plateau. And it companies with the higher variability of the amount of annual glacial melt water. The feature of the glacier melt water variation takes disadvantage to the usage of the water resource of the Tibetan Plateau and its surrounding regions.Fouth, the glacier area will enlarge under the temperature decreasing scenario. The velocity of the temperature decreasing influences the variation of the Tibetan Plateau obviously, which impacts the process of the glacier area variation and the procedure of the glacier melt water volumn at the same time. The variation of the glacier melt water is complex under the temperature decreasing scenario more than the feature under the temperature rising scenario. The curve of the glacier melt water variation under the temperature decreasing scenario is quite different as the deceasing velocity change.The last, but not the least, the main feature of the tendency of the glacier melt water runoff is it increases in the start period and decreases in the last period in higher speed under the different climate change scenarios. On the other hand, the characteristics under different climate change scenarios are different to each other. In details, the glacier area will last shrink until die out if the temperature rising consistently, while the glacier area will enlarge as the temperature decreasing. In spite of the difference of the tendency of the glacier variation under different climate change scenarios, the sensitivity of the glacier system will stable always.更多还原