云南中部区域气温变化特征及其受城市化影响程度分析

Spatial-temporal Variation of Surface Air Temperature and Its Influence by Urbanization in Central Yunnan Plateau

利用云南中部区域1961—2010年逐月气温资料,采用趋势系数、气候倾向率、Mann-Kendall突变检验、Morlet小波等方法分析该地区气温的时空变化特征,并采用城郊对比法分析城市化对于气温变化的影响程度。结果表明:(1)该地区年均气温上升趋势明显,年均气温存在着24 a的主周期,并于1997年发生了突变,之后进入了一个显著增暖时期。四季平均气温均呈上升趋势,其中冬季气温增幅最大。(2)除西北部的元谋干热河谷存在降温趋势外,其余地区均呈现增温趋势,升温中心位于城市,其中以昆明的升温趋势最为显著。(3)城市化对气温序列变化趋势的影响显著,城市化引起的增温速率在冬季最大,而城市化对气温变化趋势贡献最高的季节则为春季。(4)昆明的城市化增温速率最大,楚雄次之,玉溪最弱;三市的热岛强度从1985年开始逐年增强,2000年后达到最高值,之后趋于平缓;冬春季节的城市化增温速率要明显高于夏秋季节,城市化增温贡献最高的季节为春季。

Monthly mean surface air temperatures from 37 meteorological stations over the Central Yunnan Plateau were analyzed for temporal-spatial variation patterns from 1961 to 2010. Trends of air temperature were identified using linear regression and Mann-Kendall test. The morlet wavelet analysis method was used to detect the change interval of annual mean air temperatures. On the basis of classifying 37 meteorological stations into urban and rural stations, the extent and relative contribution proportion of urbanization effect are obtained by comparing the differences between the air temperature change trends of urban stations and their corresponding rural stations. Annual mean air temperature showed a significant warming trend. Seasonal mean air temperature appeared rising trend, and the trend was more significant in the winter than in the other seasons. The morlet wavelet analysis revealed that the annual mean air temperature fluctuated significantly with the interval of 24 years. The Central Yun- nan Plateau tends to be warmer after an abrupt changes in annual mean air temperature occurred in 1997. Seasonal/annual mean air temperature tends to increase in most areas, higher warming trend appeared in urban area, notably in Kunming, whereas the Yuanmou dry-hot valley of Jinsha River experienced a decreasing trend during the past decades. The regional mean air temperature series was significantly impacted by urban warming. The biggest trend of urban warming is in winter. The urbanization-induced warming trend in Kunming increased with the biggest ratio, followed by warming trends in Chuxiong and Yuxi. Since 1985, the urban heat island intensity has been gradually increased until 2000 in all three cities, Meantime, the urbanization-induced warming trend in the winter/ spring was more significant than in the summer/autumn. The contribution of urban warming in spring increased with the biggest ratio.