区域输送对天津臭氧污染的影响

采用大气化学模式定量估算2019年4月~9月区域输送对京津冀区域,特别是天津市O₃浓度的影响,分析天气形势和气象条件与区域输送的关系。结果显示,京津冀区域13个城市O₃以区域输送贡献为主,不同城市O₃差异较大,天津本地贡献占比24%,区域输送以京津冀区域其他城市和山东为主,共贡献48.3%。低压、低压前和低压后形势下,O₃区域输送占比最高。途径天津偏南区域的气流是造成天津高浓度O₃污染的重要因素,也是区域输送的主要路径。随着O₃浓度升高,输送贡献占比呈逐步上升趋势,重度污染时本地生成与区域输送贡献相当。一次典型O₃污染过程分析表明,高温强辐射天气和有利的天气形势促进O₃本地生成,西南气流和弱下沉气流下的区域输送共同维系了这场持续3d的连续污染过程。

Effect of regional transport on ozone pollution in Tianjin

The atmospheric chemistry model was used to quantitatively estimate the impact of regional transport on the ozone (O₃) concentration in Beijing-Tianjin-Hebei region during April to September of 2019, and Tianjin was the focus of analysis. Additionally, the relationship between the weather pattern and meteorological conditions with O₃ regional transport was also analyzed. The results showed that O₃ pollution of 13 cities in the Beijing-Tianjin-Hebei region was mainly attributed to regional transport, with distinguished contribution in different cities. The local generation for O₃ pollution in Tianjin accounted for 24%. The O₃ regional transport from other cities in the Beijing-Tianjin-Hebei region and Shandong province totally accounted for48.3%. O₃ regional transport occurred frequently under the weather pattern of low pressure, front and rear of low pressure. The southern air flow passed Tianjin was an important factor generating high O₃ concentration, and it was the main pathway of O₃ regional transportation for Tianjin. With the rise of O₃ concentration, the contribution of O₃ regional transportation increased gradually, and the contribution of O₃ regional transportation was comparative to local generation in severe O₃ pollution. The analysis of a typical O₃ pollution event showed that the high temperature and strong radiation as well as favorable weather pattern promoted the local formation of O₃. The O₃ regional transport from southwest direction and weak downdraft jointly maintained this O₃ pollution event for 3 days.