城市化对云南高原楚雄市近年来雨岛效应的影响研究

Influence of urbanization on urban rain island effect of Chuxiong City on Yunnan Plateau in recent years

利用2010-2015年楚雄市城市和郊区共10个气象站点的降雨量资料,采用城市和郊区对比等方法分析楚雄市的降雨特征,运用灰色关联度分析各气象因子、人文因子与雨岛强度的关联程度。结果表明:楚雄市近年来雨岛效应明显,降雨中心主要位于城市及其下风方向的苍岭;当出现小雨和中雨,大尺度大气环流场比较弱的条件下,楚雄市城市雨岛强度较强;楚雄市干湿季分明,月降雨量主要集中在雨季,城市雨岛效应在雨季更显著。影响楚雄市雨岛强度的因素中,关系最为密切的人文因子则为城区面积,而关系最为密切的气象因子是日照时数,且人文因子占较大比重。

Although many studies on urban rain island have been carried out, but mainly focusing on large cities such as Beijing, Shanghai, Lanzhou, Urumqi, and Kunming, the studies on small and medium-sized cities and comparison between cities and adjacent suburbs are few. With the fast development, the impact of urbanization development in ecologically weak area on regional climate draws much concern in recent years. Chuxiong City, located in the middle part of the Yunnan Plateau, belonging to South Asia monsoon zone, is very vulnerable to climate and suffers frequent natural disasters in recent years. Nowadays, the establishment of many encryption weather stations in Chuxiong City and its suburbs since 2010 enhances reliability of data. Based on the 6-year me- teorological data of 10 weather stations in Chuxiong and social statistic data, this paper made comparison analy- sis of the spatial-temporal distribution of rain island between Chuxiong City and its suburbs, and discussed the mechanism of the comparison result by using grey relational analysis method. The results show that the minimum precipitation appeared in 2012, and the maximum precipitation appeared in 2015. Generally, 6-year average precipitation was less than the multi-year average. Rain island intensity in Chuxiong presented the trend of decreasing first and then increasing. The maximum rain island intensity appeared in 2010 （218.0 mm）, and the minimum rain island intensity appeared in 2012 （0.1 mm）. Seasonally, the maximum rain island intensity appeared in Sep-tember （25.0 mm）, and the minimum rain island intensity appeared in February （0.0 mm）. Besides, rain island intensity in rainy season （ 19.0 mm） was greater than that in dry season （ 10.0 mm） ;the days of total precipitation in Chuxiong City was greater than those in its suburbs. The rain island effect was especially obvious in light rain and moderate rain, but weak in heavy rain and unobvious in rainstorm. Spatially, rain island intensity mostly ap- peared in Chuxiong City and its leeward Cangling station due to the development of city, heat island effect, barrier effect of city, and increasing condensation nucleus of city. Through grey relational analysis, the most remark- able humanity factor that affected the rain island intensity in Chuxiong was urban built-up area; the most remarkable natural factor that affected the rain island intensity in Chuxiong was sunshine duration. The significance of humanity factor was greater than the significance of natural factor, indicating that urbanization is a main factor for accelerating rain island intensity in Chuxiong City. Conclusions in this paper can contribute to the disaster prevention and reduction, and sustainable development in Chuxiong.