摘要
根据常规气象观测资料以及MODIS卫星气溶胶产品,分析了西安近50 a总辐射变化特征及其相关影响因子。结果表明:西安地区1961-2005年总辐射变化经历了"持续"、"变暗"、"变亮"、"再变暗"4个阶段,西安总辐射的变化幅度较全国平均变化幅度大,其"变亮"过程开始于1985年,较全国平均时间略早;西安4个季节总辐射总体均呈现出下降趋势,其变化幅度存在一定差异。通过对云量、气溶胶、水汽压、相对湿度等影响因子的分析,水汽压和相对湿度对总辐射变化影响不明显,总云量和气溶胶的变化对西安总辐射的变化存在较显著的影响,春、夏季总辐射的变化主要受云量和气溶胶直接辐射强迫的共同影响,其中总云量的变化在一定程度上决定了总辐射变化的振幅,城市发展所导致的气溶胶增加所产生的直接辐射强迫作用可能决定了总辐射的总体下降趋势;秋、冬季节的总辐射下降趋势主要与气溶胶的直接辐射强迫有关。
In this study, nearly 50 years of diurnal surface solar radiation data and nearly 60 years of diurnal mete- orological data, including total cloud amount, visibility, water vapor pressure and humidity, and 10 years of MO- DIS aerosol products, have been analyzed to examine the regional surface solar radiation change and its impact fac- tors over Xi ＇an City, Shaanxi Province, China. We find that there is a significant decreasing of surface solar radia- tion from 1970s to 1980s. From 1974 to 1984, surface solar radiation over Xi＇an decreased by approximately 18.2 % ~ （10 a） -1, and increased by 14.9 % ~ （ 10 a） -1 from 1985 to 1995, form 1996 to 2005 there also a de- crease by 15.2 % ~ （ 10 a） -1 The average decreasing trend of surface solar radiation over Xi ＇an was larger than that over the mainland in China and the time of ＂brightening＂ period was a little earlier over Xi ＇an. The seasonal variation of surface solar radiation shows that although there was some difference in variation scope of total solar ra- diation, there was a basically downtrend in four seasons. The variation in summer and autumn was most similar with annual change. While in spring there was an obviously decreasing from 1963 to the end of 1980s, then it began to increase slowly. In winter there was a steady decline of surface solar radiation since 1963. In order to find out the main course of decrease in surface solar radiation, we analyzed the principal meteorological factors contributed to surface solar radiation. First we studied the variation of total cloud amount, which may be one of the dominant af- fecting factors. Generally the increasing of total cloud amount can reduce the amount of solar radiation reaching the surface of the earth. The average decreasing trend of annual total cloud amount suggested that there may be another important factor for the decrease of annual solar radiation. Further more, after analyzed water vapor pressure, rela- tive humidity, visibility and aerosol optical depth. W
出处
《干旱区地理》
CSCD
北大核心
2012年第5期738-745,共8页
Arid Land Geography
基金
陕西省气象局基金项目
陕西省气象局重点项目(2010Z-6)
关键词
总辐射
气溶胶
云量
直接辐射强迫
surface solar radiation
aerosols
total cloud amount
direct radiative stress
