西安太阳总辐射时空变化特征及对城市发展的响应

根据西安辐射站太阳总辐射资料和周围23个气象台站日照百分率资料,建立1961-2009年西安市太阳总辐射资料时间序列,运用模糊聚类分析法将全市分为3个区,采取滑动t检验法进行突变检验及阶段分析,研究西安太阳总辐射的时空分布及变化特征.同时引用西安历年城区人口数据,对城区太阳总辐射与城市发展进行了相关性分析.结果表明:西安太阳总辐射具有东部多、西部次之、中部少的分布特征；1961-2009年呈波段减少的变化趋势,线性倾向率为-2.01％/10a,其中1977-1991年为显著减少阶段,以中部减少幅度最大；其间出现两次突变,突变年分别为1977年及1992年；城市发展带来大气污染物的增加,造成西安城区太阳总辐射对城市发展有较大的响应,西安城市发展对太阳总辐射季节影响上表现为冬、夏季远大于春、秋季.

Characteristics of spatial and temporal variations of global solar radiation in Xi'an and relevant response in urban development

Variations in the distribution of solar radiation on the earth surface can fundamentally alter characteristics of temperature, humidity, precipitation and atmospheric circulation, and are thus considered important indicators in the evaluation of climate change. All Intergovernmental Panel on Climate Change (IPCC) Assessment Reports contain special chapters that illustrate how solar radiation variations have been used to indicate or deduce global climate change. Given the current global trend of energy intensity triggered by over-exploitation of fossil fuels and global warming caused by excessive greenhouse gas emissions, energy from solar radiation represents the cleanest form of energy that can be used directly by humans. Therefore, solar radiation is a priority within the area of research on natural energy resources. Xi''an is the political, economical and cultural center of Shaanxi Province. The city is located at the center of the Central Shaanxi Plain. This location has the Weihe River to the north and the Qinling Mountains to the south. It has a total area of 10,108 square kilometers, an urban area of 369 square kilometers, and a population of over 8.4346 million. Xi''an was one of the four great capital cities of the ancient Chinese civilization. Research on solar radiation in Xi''an and its impact involves data from only a single point, which were analyzed in the 1990s. This research was on natural resources in Northwest China. Therefore, there has been no systematic and in-depth investigation of solar radiation characteristics in the area around Xi''an. According to data on global solar radiation from Xi''an radiation stations along with percentage of sunshine data from 23 nearby national meteorological stations, this paper presents time series ofglobal solar radiation data from the period 1961 to 2009. We apply fuzzy cluster analysis methods to divide the city of Xi''an into three sections-middle (section I), eastern (section II), and western (section III). We use the sliding T method to conduct mutation testing and phase analysis, and we study temporal and spatial distributions as well as variation of the global radiation. We also perform correlation analysis of the global urban solar radiation and urban development, with reference to Xi''an urban population data over the years. The results show that Xi''an global solar radiation had the greatest distribution features in the eastern section, less in the western section, and least in the middle section. The time series from the period 1961 to 2009 reveal a band decrease trend, which has a linear rate of decrease at -2.01%/10a. There was a period of reduction from 1977 to 1991. In this period, the greatest band reduction extent was found in the middle section. There were two years of mutation, 1977 and 1992. With urban development, there was an increase in the contamination of the atmosphere. This in turn caused urban global solar radiation in Xi''an to have a relatively large impact on such development. This was demonstrated by the seasonal patterns. The impact was more evident in winter and summer seasons, compared with the spring and autumn seasons.