北京地区城市热岛强度变化对区域温度序列的影响

CHANGE IN URBAN HEAT ISLAND MAGNITUDE AND ITS EFFECT ON MEAN AIR TEMPERATURE RECORD IN BEIJING REGION

通过对北京地区20个台站1961～2000年月平均温度资料的对比分析,证实热岛效应对城市气象站记录的地表平均气温的绝对影响随时间显著增大,近20 a尤为突出,但其相对影响即热岛增温对全部增暖的贡献却呈下降趋势.近40 a来,北京地区的国家基本、基准站平均温度距平序列与被认为不受城市热岛影响的郊区站平均温度距平序列差异明显,由于热岛效应加强因素引起的国家基本、基准站平均年温度变化速率为0.16 ℃/(10 a),对整个时期全部增温的贡献达到71%;近20 a来热岛效应加强因素使北京地区国家基本、基准站年平均温度每10 a增暖0.33 ℃,对该时期全部增温的贡献达到49%.城市热岛效应加强因素对国家基本、基准站季节平均温度上升的贡献在夏、秋季高,冬季最小.本文的结果说明,目前根据国家基本、基准站资料建立的全国或较大区域平均温度序列可能在很大程度上保留着城市化的影响,有必要做进一步的检验和订正.

Using a data set of monthly mean temperature from 20 stations, the effect of urban heat island magnitude evolution on mean surface air temperature records of the last 40 years in Beijing region was analyzed. Two stages, a short cooling period between 1961 - 1969 and a significant warming period after 1969, were observed for both the urban and rural annual mean temperatures in Beijing area, and an obvious warming trend for each station is detected. The warming rate in winter is much higher than in any other seasons. It was also noted that the temperature anomaly series as calculated using the data from Beijing Station and the national basic/reference stations of the study area are significantly impacted by urban warming, especially for the last 20 years. Although the positive tendency of temperature anomalies is much greater in winter than in any other seasons, the urban warming is generally stronger in warm seasons. By analyzing the difference of temperature changes rates between basic/reference stations and rural stations, we could further obtain the warming rate induced by urbanization, and could calculate the relative contribution of urban warming to the total change in mean temperature. The contribution for annual mean temperature change of the basic/reference stations in Beijing area reaches to 48.5 % for period of 1979 - 2000 and 71.1% for period of 1961 - 2000. It is also obvious that the contribution generally increases from winter and spring to summer and autumn. During 1961 - 2000, the recorded warming in summer and autumn can be entirely accounted for by the urbanization effect. Above all, these results indicate the essentiality to pay more attention to the effect of urban heat island magnitude change on long-term mean temperature series at least on regional scale.