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冷空气背景下江苏重污染特征与气象条件相关关系分析
曹璐1, 刘端阳2, 周鹏3, 严文莲1, 陈昊1
1.江苏省气象台;2.江苏省气象科学研究所;3.南京市气象局
摘要:
统计2013-2015年江苏重污染个例,分析冷空气背景下重污染天气特征与气象条件,研究表明:冷空气下江苏重污染浓度等级多为5级,6级污染仅14%主要在中路,东路概率很小;中路、西路易出现区域性、连续性重污染,首要污染物PM2.5为主,O3次之;东路多单点污染,连续污染概率较少,O3污染概率高。重污染日高空冷空气主体偏北,中低层为槽后脊前NW气流或有弱切变,地面冷高压前部;层结稳定,50%以上有逆温,混合层高度<1.2 km ;重污染前日与当日风速< 4米/秒,无降水或< 1.0 mm弱降水;中路、西路冷空气污染输送贡献大于东路,上游污染负输送,有强逆温、小风速的“静稳”天气,重污染仍可能加剧;在有利重污染天气发生的环流背景下,南京污染浓度24小时日最大增幅,中路冷空气小于150μg/m3,西路和东路小于100μg/m3;重污染天气的发生,是本地污染、外源输送和局地不利污染扩散的气象条件共同作用造成。
关键词:  冷空气路径,重污染特征,气象条件
DOI:
分类号:P458.1+1
基金项目:江苏省环境监测科研基金项目
Characteristics of Severe Air Pollution in Jiangsu Province and its Relationship with Meteorological Conditions under Cold Air
Abstract:
By analyzing the severe air pollution cases in Jiangsu Province during 2013-2015, we investigated the characteristics of meteorological conditions during those polluted episodes in this study. The results showed that in Jiangsu Province, the level of air pollution happened under cold air was mostly in Level 5. There were only 14% of all events in Level 6, which mostly took place when the cold air was from central pathway, and rarely cases were from easterly pathway. Generally, the air pollution episodes under central and western pathway were regional and continuous, with primary pollutant of PM2.5, followed by O3; while those under eastern pathway were local and short, frequently with primary pollutant of O3. During severe pollution episodes, at high altitude, the cold air was mainly at north side of Jiangsu Province; at mid and low altitude, there was northwest airflow in front of ridge or weak shear; on the surface, Jiangsu was in the front of cold air. The stratification was stable with the mixing layer height less than 1.2 km, and there were vertical temperature inverse happened of more than 50% events. At the day and the day before the severe pollution episode, the wind speed was generally less than 4 m/s, and there was no or weak precipitation (<1.0mm/day). Compared to the easterly pathways, more air pollutants were transported from central or westerly pathway. The heavy pollution might be intensified under stable weather conditions with negative transportation upstream, very strong inverse and weak wind. In the circulation beneficial to the severe pollution, the maximum elevate of the 24-h mean concentration in Nanjing was less than 150μg/m3 from central-pathway cold air and less than 100μg/m3 from westerly and easterly pathway cold air. Overall, the severe air pollution in Jiangsu province was attributed to the combined contributions from local emission, regional transportation and unfavorable weather conditions.
Key words:  Pathway of cold air, characteristics of heavy air pollution, meteorological conditions