摘要
四川盆地具有四面环山的深盆地地形,亦是我国O_(3)污染的重灾区.为深入了解地形对大气环境变化的影响,本文利用近6年(2017—2022年)春末(5月)近地面O_(3)观测资料和ERA5气象再分析资料,研究四川盆地西部地区山谷风环流对近地面O_(3)浓度及其污染变化的影响程度和作用机理.结果表明:①四川盆地西部地区具有显著的山谷风环流.研究时段山谷风日的发生频率达33.3%,白天盆地内偏东气流沿山坡爬升,夜间偏西气流沿山坡下沉.夜间02:00—07:00为山风控制时段,白天13:00—18:00为谷风控制时段.②山谷风加重了四川盆地西部的O_(3)污染,使近地面O_(3)浓度增加了(6.7±6.1)μg·m^(-3)(7.5%±5.1%).依据MDA8 O_(3)超标标准,计算O_(3)污染日数,山谷风使O_(3)一级和二级超标率分别增加了19.1%和10.1%;使谷风控制时期的O_(3)小时超标率增加了3.5%±2.0%.③山谷风日的近地面平均风速较多年月平均上升了18.1%,其中山风和谷风控制时期风速分别增加了25.2%和26.7%,有利于白天盆地内高浓度O_(3)向西部地区输送累积,夜间高原山坡低浓度NO向下传输到盆地西部,减弱O_(3)滴定消耗.④盆地西部谷风期间近地面气温上升了8.7%,加强了光化学反应,使白天O_(3)浓度升高;山风期间地面气温降低了1.4%,促进了近地面大气层结稳定,有助于夜间近地面O_(3)累积增加.
The Sichuan Basin(SCB),characterized by a deep basin surrounded by mountains on all sides,suffers severe O_(3) pollution.To deeply understanding the impact of topography on atmospheric environment,this study utilizes the near-surface O_(3) observations and ERA5 meteorological reanalysis data in May from 2017 to 2022,investigating the effect and mechanisms of mountain-valley breeze(MVB)on the variations in near-surface O_(3) concentration and pollution in the western SCB.The results show that:①The western SCB experienced significant MVB,with 33.3%of occurrence frequency during the study period.During the daytime,the easterly airflow ascended along the slope,while during the nighttime,the westerly airflow descended along the slopes.The period from 02:00 to 07:00 was dominated by mountain breeze(MB),and the period from 13:00 to 18:00 was dominated by valley breeze(VB).②MVB deteriorated O_(3) pollution in the western SCB,increasing by(6.7±6.1)μg·m^(-3)(7.5%±5.1%)in near-surface O_(3) concentration.According to the MDA8 O_(3) concentration limitation,the light and moderate O_(3) pollution days rose by 19.1% and 10.1%,respectively.In addition,the rate of hourly O_(3) concentration exceeding 160μg·m^(-3) during valley breeze-controlling period increased by 3.5%±2.0%.③The nearsurface average wind speed on MVB days increased by 18.0% compared to the multi-year average for May,with 25.2% and 26.7% increments during the periods controlled by MB and VB,respectively.These would facilitate the transport of high-concentrations O_(3) from the inner basin to the western region during the daytime and low-concentrations NO from the plateau slope to the western SCB with poor NO titration during the night.④During the VW period,the near-surface temperatures increased by 8.7%,which enhanced photochemical productions and consequently elevated daytime O_(3) concentrations.During the MW period,surface temperatures decreased by 1.4%,promoting the form of stable atmospheric boundary layer at night,contributing to the accumula
作者
鲁震
张郁青
赵天良
胡俊
李智宽
王德洋
LU Zhen;ZHANG Yuqing;ZHAO Tianliang;HU Jun;LI Zhikuan;WANG Deyang(Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration and Collaborative Innovation,Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science&Technology,Nanjing 210044;Fujian Provincial Key Laboratory of Environmental Engineering,Fujian Academy of Environmental Sciences,Fuzhou 350011)
出处
《环境科学学报》
CAS
CSCD
北大核心
2024年第10期83-90,共8页
Acta Scientiae Circumstantiae
基金
国家重点研发计划(No.2022YFC3701204)
国家自然科学基金(No.42275196)。
关键词
地形效应
山谷风环流
O_(3)污染
四川盆地西部
topographic effects
mountain-valley breeze
O_(3) pollution
western Sichuan basin
