北京中央商务区(CBD)城市热岛效应的研究

利用2012~2013年北京中央商务区（Central Business District，CBD）加密观测资料，分析CBD区域城市热岛（Urban Heat Island，UHI）强度日变化和空间变化特征及其影响因子。研究发现，CBD区域气温高于周边自动站气温，平均偏高0.64℃；CBD区域城市热岛强度呈现夜间强、白天弱的现象，中午甚至存在“城市冷岛”现象。季节平均UHI日变化表现为:在夜间，秋季最强，冬季次之，春季和夏季较弱；在白天，夏季最强，冬季次之，春季和秋季较弱。相对于晴朗无风天气，雾、雨、大风等天气对城市热岛有抑制作用，并结合小波分析结果发现，秋季城市热岛强度强于冬季是由于冬季雾、雨、大风等天气过程发生比例较高的缘故。CBD区域城市热岛空间变化特征研究发现，花园、学校等绿地有助于缓解城市热岛效应。雾日、雨日和大风日的CBD区域城市热岛强度空间变化标准差比晴朗无风日小。

A Study on Urban Heat Island Effect in Beijing Central Business District (CBD)

The diurnal and spatial variations of urban heat island (UHI) and their influence factors in Beijing central business district (CBD) are investigated by using the dense air temperature data measured in this area during 2012-2013. The results illustrate that the CBD air temperature was 0.64℃ higher than the surrounding area. And the UHI in the CBD was stronger in the nighttime and weaker during the daytime, while the "urban cold island" even occurred at the noon. Analysis of seasonal means of the UHI shows that the strongest UHI in the nighttime occurred in the autumn, followed by that in the winter, and the weakest UHI occurred in the spring and summer. During the daytime, the strongest UHI occurred in the summer, followed by that in the winter and the weakest UHI was found in the spring and autumn. Foggy, rainy, and windy days could restrain the UHI compared to the situation in sunny days. Combined with the wavelet analysis results, the reason why the UHI in the autumn was stronger than in the winter is attributed to the high occurrence frequencies of foggy, rainy, and windy days in the winter. Analysis of the UHI spatial variation in the CBD shows that gardens, schools and other public lands could ease the UHI effect. And the standard deviation of spatial variation of the UHI in the CBD in foggy, rainy and windy days was smaller than that in sunny days.