平流层-对流层交换对东亚地区对流层臭氧近期变率的影响研究

The tropospheric ozone is one of the most important pollutants of the air, which is harmful to public health and damages the ecological environment. Recently, the tropospheric ozone over China has been increased remarkably and ozone pollution events happen more frequently. A number of studies have been attributed this increase in ozone to the increased emissions of ozone precursors, which is, however, only part of the reason. Further investigations are necessary to give a comprehensive explanation. The Stratosphere-Troposphere Exchange (STE) caused transportation of ozone from the stratosphere to the troposphere is one of the main resources of tropospheric ozone. Changes in the amount of ozone STE influence the tropospheric ozone significantly. Recently, the stratospheric ozone is expected to be recovery after the Montreal Protocol. At the same time, several studies pointed out that the Brewer-Dobson (B-D) Circulation has been decreased recently, despite its long-term increase over the past decades as reported by previous studies. The response of ozone STE to the recent ozone recovery and slower B-D circulation is still unclear, while its potential impacts on the tropospheric ozone over East Asia is largely unknown. Here, we use observations, reanalysis data as well as model simulations, with methods of the LMS (Lower Most Stratosphere) budget method, the Brewer-Dobson Circulation method and the stratospheric ozone tracer method to investigate the recent variability of ozone STE over the globe and East Asia. The Brewer-Dobson circulation method will be extended to 3 dimension to get the regional STE amount. The relative contribution of the ozone STE to the recent variability of tropospheric ozone over East Asia will be also investigated. This project focuses on the ozone pollution and relates it to the STE processes, with a purpose to improve our understanding to the recent increase in tropospheric ozone over East Asia and to give a better prediction to the future tropospheric ozone evolution.

臭氧是一种重要的污染物，对人体健康和生态环境有严重危害。当前，我国对流层臭氧迅速增长，臭氧超标事件频发。已有研究多将其归因臭氧前体物的增长，但只能部分解释此现象。平流层-对流层交换（STE）是对流层臭氧的重要来源，STE的变化势必对对流层臭氧产生影响。目前对于平流层臭氧恢复及Brewer Dobson（BD）环流减弱背景下STE过程的相应变化及其对东亚对流层臭氧的影响还缺乏清晰的认识。本项目拟基于最新的观测、再分析资料并结合数值模拟，结合臭氧收支法、BD环流法及模式标记示踪法等多种方法分析全球和东亚地区STE的变化特征，量化其对东亚对流层臭氧近期变率的相对贡献。鉴于常用的BD环流法多为纬向平均，不能获得局地的STE，本项目将扩展该方法至3维。该项目着眼于大气复合污染重点之一的臭氧污染问题，重点关注STE过程对其影响，期望能增进对对流层臭氧近期变率的理解，为预测其未来变化趋势提供依据。

臭氧是一种重要的污染物，对人体健康和生态环境有严重危害。当前，我国对流层臭氧迅速增长，臭氧超标事件频发。平流层入侵（SI）是对流层臭氧的重要来源，SI的变化势必对对流层臭氧产生影响。本项目综合利用多种卫星观测数据（GNSS-RO、SWOOSH、C3S等）、IAGOS民航观测数据、多种再分析资料（ERA5、MERRA2、JRA-55、ERA-Interim等）以及模式数值模拟（MOZART、CAM-Chem、CESM-WACCM等）研究了全球变化背景下上对流层-下平流层（UTLS）区域温度、水汽和臭氧的季节、年际、年代际变率及近期变化趋势，评估了SI过程对我国东部地区春、夏季臭氧污染的相对贡献。.本项目主要取得以下研究成果：1）发现2002-2017年期间UTLS区域增暖、平流层下层臭氧增多、对流层上层臭氧减少的变化趋势；2）揭示了太阳11年周期对UTLS区域温度和水汽的年代际变率的影响机制；3）指出模式垂直分辨率对正确模拟UTLS区域热力学结构及其季节-年代际变率以及平流层-对流层耦合的重要性；4）分析了春季SI过程影响我国地面臭氧污染的事件，发现春季强SI事件可使得地面臭氧异常升高15ppmv，对地面臭氧污染事件的相对贡献~15%；5）统计了2011-2017年夏季我国东部地区SI事件的发生频率，定量评估了SI事件对我国东部地区夏季臭氧污染的相对贡献，为该地区夏季臭氧污染的预报与防治提供了科学依据。.在项目支持下，项目负责人及其他成员在国内外top期刊上发表SCI学术论文5篇，相关研究成果受到生态环境部的高度重视，对我国臭氧污染标准制定及防控具有重要启示意义。