【摘要】 应用北京地区地面气象观测台1990~2004年10月的气温资料,分析了近15年来北京秋季城市热岛的特征,结果表明,北京秋季夜间城市热岛要强于白天。此外,对比分析了一个强热岛和一个弱热岛的特征及其气象影响因子,结果表明,北京秋季夜间特定条件下存在强热岛,白天城市强热岛会减弱消失,城市强热岛的日变化非常明显。夜间城市强热岛形成和维持是多个因子综合作用的结果。白天日照充足的晴夜,北京城郊地面风场很弱(≤1.0 m.s-1),同时城区垂直方向47 m以下大气风场持续很弱(≤1.0 m.s-1),城区320m以下大气持续存在强逆温。日落后郊区地面大气降温速率和幅度远大于城区,促使夜间强热岛的形成和维持。白天日出后太阳辐射的加热作用所引起的郊区地面大气升温速率和幅度大于城区,城区大气稳定度的减弱以及城区大气逆温的消失是夜间强热岛减弱并最终消失的重要原因。更多还原

【Abstract】 Based on the data of 20 meteorological stations in Beijing,the characteristics of Beijing autumn urban heat island(UHI)were analyzed.The results show that the Beijing autumn UHI in the evening is stronger than that in the daytime.In addition,with the data got by three automatic meteorological stations and the 325 m meteorological tower of LAPC,the characteristics and its meteorological influencing factors of a strong UHI and a weak one were analyzed contrastively.The strong UHI occurs in the evening under some specific conditions,but it weakens and disappears in the daytime,the diurnal variation of the strong UHI is very obvious.And the cooling rate and extent of the suburban surface atmosphere is bigger than those of the urban surface atmosphere after sunset,which directly leads to the formation of the strong UHI.The heating rate and extent of the suburban surface atmosphere is bigger than those of the urban surface atmosphere after sunrise,which directly causes the weakening and disappearance of the strong UHI.In the clear evening of the sunny day,the surface winds maintain weak(≤ 1.0 m·s-1) over the suburb and urban areas,the wind below 47 m over urban area maintains weak(≤1.0 m·s-1) too,and the strong inversion temperature in the atmosphere layer below 320 m over urban area occurs and maintains all the night,all of these have important effects on the formation and maintenance of the autumn strong UHI.In the daytime the solar radiation has the most important effects on the weakening and disappearance of the strong UHI,it makes the suburban surface atmosphere temperature rise faster and more than the urban atmosphere temperature,and also the strong inversion temperature disappear,and further the strong UHI weaken and disappear in the end after about 1000 LST.更多还原