成都地区大气混合层高度对霾强度的响应特征

Response Characteristics of Atmospheric Mixing Layer Height to Haze Intensity in Chengdu Area

摘要: 基于成都地区2014~2018年冬季14个站点气象要素数据以及同期细颗粒物(PM_2.5)质量浓度，筛选了研究期间16次持续性霾天气过程，利用罗氏法计算了成都地区大气混合层高度(MLH)，对该地区霾天气过程MLH的时空分布特征进行了分析。结果表明：(1) 成都地区霾天气过程平均MLH (441.89 m)总体低于冬季平均MLH (501.83 m)；(2) 基于霾天气过程MLH，利用K-Means聚类方法将成都地区分为I区、II区和III区，三个区域对应的平均MLH分别为480.31 m、419.70 m和394.89 m；(3) 随着霾强度由轻微霾到重度霾的渐进演化，MLH均呈现出递减的变化趋势，I区、II区和III区MLH与PM_2.5浓度的相关系数(R)分别为−0.24、−0.15和−0.14 (均通过了α = 0.05的显著性检验)。

Abstract: Based on data of multiple meteorological elements from 14 stations in Chengdu during the winters of 2014~2018 and the concurrent mass concentrations of fine particulate matter (PM_2.5), 16 regional haze events during the study period were screened out. The atmospheric mixing layer height (MLH) in Chengdu was calculated using Nozaki method, and the spatiotemporal distribution characteristics of MLH during haze events in this region were analyzed. The results showed that: (1) The average MLH during haze events in Chengdu (441.89 m) was generally lower than the average winter MLH (501.83 m); (2) Based on MLH during haze events, Chengdu was divided into zone I, zone II, and zone III using the K-Means clustering method, with the corresponding average MLH values of 480.31 m, 419.70 m, and 394.89 m for the three zones, respectively; (3) As the haze intensity gradually evolves from slight haze to severe haze, MLH shows a decreasing trend. The correlation coefficients (R) between MLH and PM_2.5 concentration in Zone I, Zone II, and Zone III are −0.24, −0.15, and −0.14, respectively (all passing the significance test at α = 0.05).