基于LCZ的广州夏季热岛强度特征分析

Analysis of the Characteristics of Heat Island Intensity Based on LCZ in the Summer of Guangzhou

城市局地气候分区(Local Climate Zone,LCZ)是按照一定指标对城市空间分区研究城市热环境的通用方法.基于LCZ理论,甄选出广州市9个不同类型的LCZ地块进行空气温度实测,分析多个典型气象日下不同LCZ地块的热岛强度时空特征、气温变化特征和升温冷却率差异.结果表明:各LCZ地块热岛效应呈现明显的昼弱夜强的日变化规律,日出后逐渐变弱,中午最弱,且部分城市形态区域出现"城市冷岛"的现象,在日落3~5h达到最强,超过4℃;各LCZ地块平均热岛强度夜间差异明显,在0.5~2.3℃之间,建筑密度与热岛强度呈正相关.白天差异较小,均在0.5℃左右,高宽比过高的LCZ 1因建筑相互遮阴白天形成"城市冷岛",LCZ A"城市冷岛"效应明显;各LCZ地块日低温差异显著高于日高温差异,且热岛强度日变化特征与升温冷却率变化特征一致.

The local climate zone(LCZ)is an objective and standard scheme used to study Urban Heat Island(UHI)according to some indexes.Based on the criteria of LCZ,9 LCZs were selected for long-term temperature observation in Guangzhou.The temporal and spatial characteristics of UHI,temperature change characteristics and differences of temperature rise and cooling rate in different LCZ sites under typical weather days were analyzed.The obvious UHI diurnal variation is characterized by weak days and strong nights,which gradually weakens after sunrise,reaches the weakest at noon.The phenomenon of“Urban cold island”appears in some LCZ sites,reaching the strongest in 3-5 hours after sunset,exceeding 4 ℃.The average heat island intensity of each LCZ site was compared,which shows a significantly difference from 0.5 ℃ to 2.3 ℃.The building compactness was positively correlated with the heat island intensity.But little difference is found in the daytime,about 0.5 ℃.LCZ 1 presents an“urban cold island”,which is shaded by buildings due to large H/W.The“Urban cold island”effect is prominent in LCZ A.The daily maximum temperature difference of lowest temperature is significantly higher than that of the highest temperature,and the daily variation characteristics of heat island intensity are consistent with that of heating and cooling rate.