基于耦合湖模式的城市边界层模式研究太湖的气象与环境效应

Study on the meteorological and environmental effects of Lake Taihu based on the urban boundary layer model coupling lake model

本文发展了一个耦合的城市边界层—湖泊模式(RBLM-Chem-Lake),通过离线和在线两种方式对模式的模拟效果进行了检验。并通过敏感性实验分析了太湖冬季和夏季对周边地区气象特征和空气污染的影响。结果表明:(1)白天太湖对周边气象环境产生了明显的降温效应,而夜晚出现了明显的升温。冬季夜晚周边地区升温达到0.4~0.6℃,白天可以使得周边气温降低1~2℃。夏季夜晚使周边地区升温可达1~1.5℃,白天使得周边气温降低1~2℃。(2)太湖对周边地区气温的影响范围夏季远高于冬季,夏季影响范围可达到80 km,冬季影响范围平均为5 km。此外,太湖使得湖区平均边界层高度下降,湿度上升,使得苏州市区垂直风速减弱,这种影响同样在夏季更为明显。(3)太湖的存在总体上使湖区和周边地区PM_(2.5)和臭氧的质量浓度增加。在冬季PM_(2.5)污染个例中,太湖导致区域夜晚PM_(2.5)质量浓度下降,下降幅度达到4~5μg·m^(-3)。而在白天,太湖区域500 m高度以下PM_(2.5)质量浓度增加,幅度达到25~30μg·m^(-3),在500 m高度以上质量浓度下降约5~10μg·m^(-3)。夏季的臭氧污染日个例中,白天,在太湖的东岸以及苏州市区臭氧的质量浓度出现了明显的增加,可以达到10~12μg·m^(-3)。

This article has developd a coupled urban boundary layer lake model(RBLM-Chem-Lake)and verified its simulation effect through both offline and online ways.Through sensitivity experiments,the impacts of the Lake Taihu on meteorological characteristics and air pollution in surrounding areas in winter and summer were analyzed.Results show that:(1)in the daytime,the Lake Taihu has an obvious cooling effect on the surrounding meteorological environment,while at night,an obvious warming occurs.In winter,the temperature in the surrounding area rises to 0.4-0.6℃at night,while during the day,it can reduce the temperature by 1-2℃.Summer nights can increase the temperature in the surrounding areas by up to 1-1.5℃,while in the daytime,it can lower the temperature by 1-2℃.(2)The influence range of the Lake Taihu on the temperature in the surrounding areas is much higher in summer than that in winter.The influence range can reach 80 km in summer but 5 km in winter on average.In addition,the Lake Taihu reduces the average boundary layer height in the lake area and increases the humidity,which weakens the vertical wind speed in Suzhou urban area.This effect is also more obvious in summer.(3)The presence of the Lake Taihu generally increases the concentration of PM_(2.5)and ozone in the lake area and surrounding areas.In the case of PM_(2.5)pollution in winter,the Lake Taihu leads to the decrease of PM_(2.5)concentration at night in the lake area by 4-5μg·m^(-3).In the daytime,PM_(2.5)concentration in the Lake area below 500 m increases by 25-30μg·m^(-3),and the concentration decreases by about 5-10μg·m^(-3)above 500 m.In the case of ozone pollution day in summer,the ozone concentration in the east bank of the Lake Taihu and the urban area of Suzhou during the daytime increases significantly,reaching 10-12μg·m^(-3).