1993—2012年西安城区城市热岛效应强度变化趋势及影响因素分析

基于西安市及其郊区(县)7 个气象观测站1993—2012 年的气温资料,采用回归分析、Mann-Kendall 等方法分析了西安市过去20 a 城市气温、热岛强度的变化规律,从城市经济发展、城市人口增长、城市能源消费等几方面揭示其与城市热岛效应的密切联系;同时运用灰色理论分析了诸影响因素对热岛强度的相对贡献度,并对西安未来热岛强度变化趋势进行了模拟.结果表明:①西安城区和郊区(县)气温均呈现波动上升的变化趋势,城市热岛强度变化具有明显的阶段性特征,且在2000 年以后发生增强突变;②城市化的发展与城市热岛强度的变化具有密切关系,各要素相互之间呈现高度相关性,说明它们之间存在很强的传递作用;各要素与热岛强度呈现出极显著的相关关系,尤其是人口因素与热岛强度的关系最为密切,是影响热岛强度增强变化非常重要的一个综合性指标;从强度、密度和规模效应上来看,人口密度效应大于人口规模效应,经济密度效应稍大于经济规模效应,能耗强度效应大于能源规模效应;③各影响因素对热岛强度变化的贡献度存在明显差异,贡献程度最大的是常住人口数、常住人口密度和建成区面积,它们是影响热岛强度变化最为直接的因素;其余因素对热岛强度变化的贡献度相对较小,是间接的影响因素;④灰色建模显示,西安城市热岛强度在未来几年将继续呈现增强趋势.

The Changing Trend of Heat Island Intensity and Main Influencing Factors during 1993-2012 in Xi'an City

The temperature data of the Xi'an city and the suburbs (Lintong, Changan) or counties (Lantian, Zhouzhi, Huxian, Gaoling) from 1993 to 2012 were used to analyze the annual change of heat island effect intensity in Xi'an city by the method of regression analysis, Mann- Kendall analysis, etc. At the same time, we use the Grey System theory to study the influence and contribution degree of urbanization such as the economic development and population growth on the heat island effect of Xi'an city. The results show that: 1) The temperature of Xi' an urban and suburb area have presented an increasing trend since 1993. The change of heat island intensity in Xi'an city has obvious periodic characteristics, and there was a break point between 2000 and 2001. 2) There is a close relationship between urbanization and urban heat island. The factors of heat island are highly interrelated to each other, which indicated that there is a strong transfer function among them. There exists obvious relationships between heat island intensity and various factors, especially the demographic factor which is an important indicator of the urbanization. In terms of the strength, density and scale, the population density effect is greater than the population size effect, the economic density effect is slightly larger than the economic scale effect, the energy intensity effect is greater than the energy scale effect. 3) The contribution of different influence factors on heat island intensity change exists obvious difference. The most contribution to heat island intensity change is from resident population, population density and urban built- up area, and the contribution of other factors is relatively small. 4) The simulating result of Grey Theory model has showed good consistence between the actual values and fitted values, and also showed that the heat island intensity of Xi'an city will increase in the next few years.