汾河谷地大气环境容量与大气污染过程的数值模拟与敏感性分析OA北大核心CSTPCD
Numerical simulation and sensitivity analysis of atmospheric environmental capacity and air pollution processes in Fen River Valley
对汾河谷地及太原市在2015年1月的一次重污染过程运用WRF-Chem模式进行污染过程的数值模拟、观测验证和地形敏感性实验,分析了河谷地形对区域污染过程和大气环境容量的影响机制.结果表明:太原市及周边汾河谷地大气边界层环流和大气污染传输受天气系统、地形和城市化共同影响;地形环流强度明显强于太原城市热岛环流,且对其发展存在明显抑制作用,从而限制了城市大气环境容量,加剧城市近地面大气污染物的堆积和空气质量恶化;研究区域大气环境容量受气象主导风向影响:当天气主导风向偏南北向,也即与狭长的汾河谷地走向一致时,有利于该区域大气污染物的扩散清除,而当天气主导风向偏东西向时,则该区域大气环境容量明显减小,且近地面大气污染物浓度与大气环境容量之间呈强相关性,相关系数达到0.7 4;当地形敏感组实验中取消太原市周边河谷地形特征时,上述相关系数降低到0.21.
Recent years have seen rapid industrialization and urbanization in China,leading to increased urban energy consumption and atmospheric pollutant emissions,posing severe air pollution challenges in some cities.The Fen River Valley,a critical area for air pollution prevention and control,experiences significant influences on pol-lutant dispersion within the atmospheric boundary layer due to its distinctive basin topography and the urban heat island effects of its large internal cities.This study employs the WRF-Chem model to investigate a severe pollution event in the Fen River Valley and Taiyuan City in January 2015.The study includes numerical simulations of the pollution process,observational validations,and terrain sensitivity experiments.It utilizes boundary layer height and wind speed to establish the Atmospheric Environment Capacity Index(AECI),quantifying the atmospheric dispersion capability.This index,along with the spatiotemporal distribution of PM2.5 concentrations,assesses the impact of surrounding terrain on local air pollution,providing a scientific basis for air pollution control policy for-mulation.Results show that atmospheric boundary layer circulation and pollutant transport in Taiyuan City and the surrounding Fen River Valley are influenced by weather systems,terrain,and urbanization.Terrain-induced circu-lation intensity significantly outweighs the urban heat island circulation in Taiyuan and markedly impacts its de-velopment.At night,mountainous terrain confines the boundary layer height within 200 to 400 m,while a weak-ened terrain sensitivity group shows only about 100 m.However,during the day,mountains compress the boundary layer height by more than 400 m in the sensitive group.Thus,to some extent,mountains limit urban atmospheric capacity,exacerbating the accumulation of near-surface air pollutants and deteriorating air quality.This is primarily evidenced by the experiment's terrain-sensitive group,where weakening the surrounding valley's topographic fea-tures in Taiyuan slows the PM2 5 concentration rise during the accumulation phase,aligning with the Fen River Valley dynamics.Terrain is identified as a primary factor affecting the distribution of atmospheric pollutants.The Fen River Valley's north-south orientation and its broader southern section influence regional atmospheric capaci-ty,dictated by prevailing wind directions.When the dominant wind direction aligns with the valley's orientation,the increased wind speed due to the venturi effect enhances the valley's atmospheric capacity,facilitating pollutant dispersion and clearance.Conversely,when the dominant wind direction is perpendicular to the valley,mountainous terrain suppresses near-surface wind speeds and forms lower wind zones at the interface of the valley and mountains,significantly reducing the area's atmospheric capacity.This reduction strongly correlates with near-surface pollutant concentrations,with a correlation coefficient of 0.74;this correlation drops to 0.21 in the terrain-sensitive group,further underscoring the significant impact of terrain on air pollution processes.Overall,the sur-rounding mountains inhibit urban atmospheric capacity,particularly by accelerating the concentration increase dur-ing the pollutant accumulation phase.However,the specific mechanisms are complex and vary with different wind directions and diurnal cycles,suggesting that future research could further investigate the interactions between me-teorological and topographical factors and propose more effective environmental management strategies.
王孜澈;茅宇豪;郭淑雅;刘振鑫
南京信息工程大学环境科学与工程学院/江苏省大气环境监测与污染控制重点实验室/江苏省大气环境与设备技术协同创新中心,江苏南京 210044
汾河谷地大气环境数值模拟WRF-Chem地形高度与地表利用类型山谷风环流
Fen River Valleyatmospheric environment numerical simulationWRF-Chemterrain and land usemountain-valley breeze
《大气科学学报》 2024 (004)
604-619 / 16
江苏省自然科学基金委碳达峰碳中和科技创新专项(BK20220031);中国科学院重大科技基础设施开放共享重点课题(2023-EL-ZD-00013)
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