冬季天气尺度环流对我国东部气溶胶浓度时空分布影响的数值模拟

China is experiencing a vigorous economic boom in the 21th century. The subsequent increased energy demand and large amount of pollutants emission have caused serious or hazardous air pollution in winter. Such highly concentrated and widely spread particles put a threat to public health. However, based on national energy structure and developing emission control technology at present, it is difficult to fundamentally solve the problem of air pollution in a short term. Synoptic-scale circulations play important roles in modulating air pollution so that improving the understanding of the variability of the circulation pattern is quite important to forecast and prevent regional haze events in winter, China. The proposal will mainly use WRF-CHEM model, and combine with surface measurements and meteorological reanalysis data together to explore how short-term (weeks to month) synoptic-scale circulations affect the spatial and temporal variations of aerosol concentration and transport pathways. Firstly, the intensity of Siberian High implying for activities of cold air masses, and the spatial and temporal variations of aerosol concentration will be analyzed in Eastern China. Secondly, the impacts of different synoptic-scale circulations on the distribution and transport of aerosol concentration will be calculated by the WRF-CHEM model. Finally, we will establish the relationships between the aerosol pollution and the dynamical indices that reflect the intensity of high- and mid-latitude meridional circulations over Eurasia, with a view to assess the implication of these indices for aerosol concentration and transport in winter. To understand the link between synoptic meteorology and aerosol pollution will be helpful for the government to more scientifically implement the emission control and reduction measures in a short term (weeks to month) under the adverse meteorological conditions.

21世纪以来，随着经济发展对能源需求的迅猛增长，我国东部冬季灰霾污染事件频繁发生。受限于能源结构和排放控制技术，短期内空气污染问题很难彻底得到解决。在此背景下，从天气学角度理解环流形势的变化对冬季大范围灰霾天气的防治及预测有重要的现实意义。本项目从数值模拟角度来计算冬季天气尺度环流对我国东部气溶胶浓度时空分布及扩散传输的影响。研究内容包括：（1）我国东部地区冬季冷空气活动的强弱变化及同期气溶胶浓度的时空分布；（2）利用WRF-CHEM模式研究环流形势的差异对气溶胶浓度时空分布及扩散传输的影响；（3）从天气动力学角度解释动力学指数对研究区冬季气溶胶污染发生演变的指示性；（4）评估该类指数对研究区冬季气溶胶浓度时空分布及扩散传输的意义。该研究成果将有益于国家在周至月尺度上针对不利气象条件，及时制定更加科学的污染源排放管控措施，有效避免重污染事件发生。

根据研究计划，项目综合利用区域和全球大气化学传输模式（WRF-Chem模式和GEOS-Chem），并结合地面污染观测数据、再分析气象资料和气象站观测资料来阐明主要天气系统和气候变化对污染物时空分布及扩散传输的影响。我们建立了西风带季节内振荡和冬季我国东部地区气溶胶浓度时空分布的内在联系，从天气动力学机制解释了天气尺度环流形势对污染发生-发展-消散的影响。研究证实了最近青藏高原的异常变暖，并发现该地区变暖对下游地区污染发生和演变会有不同的影响。我们厘清了调节我国冬季空气污染时空分布的主要气候因素，分析了过去气候变化对污染发生发展的可能影响，结合现在观测来验证这种影响的真实性，并通过预测的气候变化来预测未来数十年空气污染的发展演变趋势。在此基础上，我们还进一步计算了新冠疫情期间天气-气候异常对我国北方霾的贡献，对项目研究结论作进一步验证。在我国持续的大气污染背景下，本研究在气候变化对我国大气污染的影响机制方面取得了进一步认识，将有助于我国大气污染的科学防控。