过去50年西安气候演变趋势的研究

The Variation of Local Climate in Xi'an City During the Past 50 Years

本文利用1951-2000年西安市气候观测数据,分析了过去50年来西安市气温、降水、相对湿度、日照百分率、晴空指数以及直接散射辐射比等参数的多年和季节变化趋势。分析结果表明:在过去50年中,西安市年平均和各季节平均气温均呈现出明显上升趋势;降水量尤其是年平均值和冬季平均值下降明显;相对湿度、日照百分率和晴空指数年平均值和季节平均值也都表现出明显下降趋势;直接散射辐射比的增加间接证明了西安市云量在过去31年里呈减少的趋势。过去50年西安市的气候演变趋势表明,人类活动的加剧已经对西安市局地气候变化产生了重要的影响。

By using climate observation data of Xi'an during 1951 to 2000,annual and seasonal variation trends of temperature,precipitation,relative humidity,sunshine percentage,clearness index and ratio of solar radiation to diffuse radiation of Xi'an during the past 50 years were analyzed.The results showed that during the past 50 years annualand seasonal temperatures in Xi'an increased obviously while annual and seasonal precipitations,relative humidities,sunshine percentages,and clearness index decreased.The increasing trend of the ratio of solar direct radiation to diffuse radiation indicates that the cloud amount had decreased during 1960 to 1991.By studying the variation trends of the climate factors in Xi'an duringpast 50 years,it was indicated that more and more activities of human beinghave great influenceon the local climate change in Xi'an.