北京中心商务区夏季近地面气温时空分布特征

Temporal and spatial characteristics of summer near-surface air temperature in Beijing central business district

利用2012年6—8月31个自动观测站气温资料,分析了北京中心商务区(CBD)夏季近地面气温时空分布特征及影响因子,并将CBD地区夏季气温监测数据与朝阳区气象站同期地面气温进行比较。结果表明:下垫面类型和人为热排放等差异是直接影响城市CBD近地面气温空间分布的主要原因。人口密集区、高层建筑与柏油路面集中区成为夏季月平均气温高值中心,较绿地覆盖区域的低值中心偏高约1.0℃;夜间人类活动及车辆使用造成的人为热排放是导致夜间城市地面气温空间差异的主要原因,而白天气温空间差异相对较小。CBD地区与朝阳站平均温差存在较明显的周内和日内变化规律,且白天和夜间二者温差基本都为正值,但夜间的差值更加明显,即CBD地区平均气温一般高于朝阳站,表现出明显的附加城市热岛效应,而且这种附加城市热岛效应具有同城市热岛强度相近的日内变化规律。进一步分析表明,不同天气条件下CBD区域的附加城市热岛强度表现出显著差异,晴好微风少云天气情况下,附加城市热岛效应更明显,主要表现在夜间;阴天、高湿天气条件下,附加城市热岛效应在白天和夜间均较弱;降水天气条件下附加城市热岛效应日夜差异最小,说明日照和太阳辐射在引起附加城市热岛效应方面起着重要作用。不同天气条件下CBD地区内部的附加城市热岛效应空间分布基本一致。

Based on the air temperature data from 31 automatic weather stations （AWS） during June to August of 2012,the temporal and spatial characteristics of summer near-surface air temperature and the possibly controlling factors in the Beijing central business district （CBD） were analyzed.Air temperature from the AWS of CBD and from the national meteorological station at Chaoyang district of Beijing was compared.The results show that the spatial distribution of the near-surface air temperature in the CBD is directly affected by the difference of underlying surface types and anthropogenic heating.The mean monthly air temperature in summer of 2012 in the densely populated,high-rising buildings and asphalt surface areas is about 1.0 ℃ higher than that in the green coverage area in the CBD.Anthropogenic heat emission due to human activity and use of vehicles at night is the main reasons for large spatial differences of the urban heating environment,while its difference in the daytime is relatively small.The daily and weekly variations of air temperature are significant in the CBD and in Chaoyang weather station.The air temperature difference between them is a positive value regardless in the daytime or at night.Surface air temperature is higher in the CBD than in Chaoyang weather station in the daytime and at night,which suggests an extra urban heat island （EUHI） effect in the Beijing CBD.The daily variations of urban heat island and EUHI are similar.Under different weather conditions,intensity of EUHI effect is different.The EUHI effect is strong in a sunny day with breeze and partly cloud,especially at night,while is weak in a cloudy day with high humidity;it is the weakest in a rainy day.Sunshine and solar radiation is important to the EUHI.The spatial distribution of EUHI in the CBD is similar under the different weather conditions.