摘要:为解析大气污染物与气象的双向反馈机制及其对气象和环境的影响，建立基于Mie散射理论的气溶胶—光学性质模块，研制气象－化学双向耦合器，以嵌套网格空气质量预报模式NAQPMS （Nested Air Quality Prediction Modeling System）为基础，建立了NAQPMS和中尺度气象模式WRF （Weather Research and Forecasting Model）的双向耦合模式（WRF-NAQPMS）。利用此模式数值模拟了2013年9月27日至10月1日的北京－天津－河北地区一次秋季严重灰霾过程。结果表明，考虑气溶胶辐射反馈的双向耦合模式模拟的气象要素和细颗粒物（PM2.5）浓度与观测结果更为一致。灰霾期间，气溶胶直接辐射效应显著改变了边界层气象要素，北京－天津－河北地区地面接收的太阳短波辐射减少25%，2 m高度的温度平均下降1 ℃，湍流动能下降20%，10 m高度的风速降低超过0.2 m/s，边界层高度下降25%，使得边界层大气更加静稳，进而造成了重污染地区污染进一步加剧，如石家庄近地面细颗粒物浓度增加可达30%。分析表明灰霾与边界层气象要素之间存在一种正反馈机制，采用该机制的双向耦合模式有利于准确模拟和预报灰霾污染过程。
关键词:气象-化学双向耦合/
WRF-NAQPMS/
灰霾/
气溶胶直接辐射效应/
大气边界层
Abstract:An aerosol-optical module based on Mie scattering theory has been implemented in the Nested Air Quality Prediction Modeling System (NAQPMS), and a new coupler has been developed to deal with the interaction between the mesoscale meteorology model WRF (Weather Research and Forecasting Model) and NAQPMS. The one-way off-line and two-way coupled WRF-NAQPMS models are compared to simulate the severe haze in the Beijing-Tianjin-Hebei area from 27 September to 1 October 2013. The results show that the simulated meteorological elements and PM2.5 concentrations from the two-way coupled model with the aerosol direct radiation effect are more consistent with observations. During the haze period, the boundary layer meteorological elements change significantly because of the aerosol direct radiation effect over the Beijing-Tianjin-Hebei area: Incoming solar radiation is reduced by 25%, the 2-m temperature decreases by 1 ℃, the turbulent kinetic energy is reduced by 25%, the 10-m wind speed decreases by up to 0.2 m/s, and the planetary boundary layer (PBL) height is reduced by 25%. These changes make the atmospheric boundary layer more stable and further exacerbate air pollution over the areas where it is already severe, for example, the PM2.5 concentration increases by up to 30% over Shijiazhuang City. The analysis indicates that there is a positive feedback mechanism between haze and boundary layer meteorology, and the two-way coupled model incorporating this feedback is helpful for accurate simulation and forecasting of haze pollution processes.
Key words:Two-way coupling of meteorology and chemistry/
WRF-NAQPMS/
Haze/
Aerosol direct radiation effect/
Atmospheric boundary layer
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