摘要
蒸发是水循环中受下垫面状况和气候变化影响最为直接的气候因子，同时也是地面热量平衡和水分平衡的重要组成部分．因此，对青藏高原蒸发量及其影响因素的研究对于分析青藏高原的气候变化及热量收支平衡具有重要的意义．本研究在分析青藏高原西藏地区蒸发皿蒸发量时间与空间分布格局及变化趋势的基础上，进一步对影响蒸发的气温、风速、日照时数、相对湿度的长期变化趋势及其与蒸发量的关系进行了分析，其结果表明：西藏地区存在“蒸发悖论”现象，即在气温升高的背景下（0．03℃／a），蒸发皿蒸发量呈下降趋势（-1．98mm／a）．西藏地区年平均蒸发量及变化趋势的空间差异性比较大，年平均蒸发潜力变化范围从1400～2600mm、变化趋势从-16～20mm／a不等；整个西藏地区蒸发量与气温的相关关系显著，气温是影响蒸发的主要因素．各因素对蒸发皿蒸发量的影响程度排序为：气温〉风速〉日照时数．相对湿度对蒸发皿蒸发量的影响不显著．在月尺度上气温是蒸发皿蒸发量变化的决定因素，但从年尺度分析结果看，风速和日照时数对于蒸发皿蒸发量的影响是导致蒸发皿蒸发量减少的主要原因．此外，由于下垫面条件及区域气候条件的不同，各因素对蒸发皿蒸发量影响程度的空间差异性很大．西藏地区蒸发皿蒸发量的减少意味着区域水循环速度的变慢，由此对于全球水气循环造成的影响需要进一步的研究．
As one of the most important components of surface energy and water balance, evaporation is a most sensitive factor to be affected by underlying surfaces and climate change. The investigation of evaporation and related factors is significant to the study of climate change and energy balance in Tibetan Plateau. Based on the analysis of spatial distribution and long-term trend of evaporation in the region, factors including air temperature, wind speed, sunshine duration and relative humidity are investigated. The results indicate that although the average temperature increased 0.03℃/a during the period from 1974 to 2001, pan evaporation decreased by - 1.98 mm/a, indicating that the so-called ＂pan evaporation paradox＂ exists in the region. The annual mean evaporation ranges from 1 400 mm to 2 600 mm, and the long-term trends from - 16 mm/a to 20 mm/a. Correlation relationship between air temperature and evaporation is significant, showing that air temperature is the main factor af- fecting the evaporation. The ranking of various meteorological factors affecting pan evaporation is that air temperature is the greatest one, wind and sunshine duration are the 2^nd and 3^rd. Relative humidity has no significant effect on pan evaporation. The air temperature determines the pan evaporation in monthly scale, resulting in the changes of permafrost by affecting ground temperature, which further results in the change of liquid water concentration on land surface. However, the decrease of wind speed and sunshine duration are the most important reasons for the decrease of the pan evaporation in annual scale. Besides, owing to the heterogeneous land surface and the different meteorological condi- tions, the importance of various meteorological factors differs from place to place. The decrease of pan evaporation means that the velocity of locally hydrological cycle becomes slow and the impact on global hydrological cycle need further investigation.
出处
《亚热带资源与环境学报》
2009年第4期20-29,共10页
Journal of Subtropical Resources and Environment
基金
国家科技攻关计划项目(2005BA901A11)
关键词
蒸发量
气温
风速
日照时数
冻土
青藏高原
evaporation
air temperature
wind speed
sunshine duration
permafrost
the Tibetan Plateau
作者简介
李景玉（1962-），女，山东淄博人，副教授，硕士，从事水文水资源与土地利用方面的研究，（电话）010-66562049，（E—mail）lijingyu@mail．clspi．org．cn．
通讯作者：张志果（1983-），男，山东泰安人，博士研究生，从事水文水资源方面的研究，（电话）13811498705，（E—mail）zhangzhigu0910@163．com．
