摘要
在对比云高仪反演数据和中尺度模式不同边界层方案模拟数据的基础上,构建天津地区混合层厚度数据集,并收集2009—2015年天津地区PM_(2.5)质量浓度和能见度资料,开展天津地区重污染天气混合层厚度阈值和相关规律研究。结果表明:2000—2015年期间天津地区混合层厚度呈现波动性逐年增加趋势,与255m气象塔观测近年天津地区逆温层底升高以及夜间边界层高度增加有较强的一致性。统计显示PM_(2.5)日均质量浓度和混合层厚度呈现指数关系,混合层厚度越低PM_(2.5)质量浓度越高,其阈值天津地区可以以200、400、600和800 m作为界限判断大气污染垂直扩散能力,当日均混合层厚度<200m时,天津地区重污染天气出现概率52%,中度以上霾出现概率46%,需要特别关注。PM_(2.5)日均质量浓度和混合层厚度的负相关并不适用于所有过程,对于输送型过程由于大气污染的输送一般由高空影响地面,在污染的起始阶段,混合层厚度的增加,反而有利于上层大气污染物向下的传输,使得近地面PM_(2.5)质量浓度升高,在运用混合层厚度阈值指标时需要特别考虑。
Based on ceilometers inversion data and simulation data,the dataset of mixed layer thickness in Tianjin were constructed,the data of PM2.5 mass concentration and visibility in Tianjin during 2009-2015 were collected,and the threshold and regularity of mixed layer thickness in heavy pollution weather in Tianjin were researched in this paper.The results show that the thickness of mixed layer kept increasing during 2000-2015,having a strong consistency with the increase of nocturnal boundary layer height and the increase of inversion base observed by meteorological tower.Statistics show that PM2.5 mass concentration has exponential relationship with the thickness of mixed layer.The lower the mixed layer thickness,the higher the PM2.5 mass concentration.The thresholds of mixed layer thickness can be 200 m,400 m,600 mand 800 m,which can be used as limits to determine the vertical diffusion of atmospheric pollution.When the thickness of mixed layer is less than 200 m,probability of heavy pollution weather is 52%,and probability of moderate haze is 46%.The negative correlation between PM2.5 average mass concentration and mixed layer thickness is not applicable to all pollution processes.For the transport of air pollution,the impact is from high altitude to ground surface.In the initial stage of pollution,the increase of mixed layer thickness is beneficial to pollutant transmission,causing the near-surface PM2.5 mass concentration to increase,which need to be considered carefully when the threshold of mixed layer thickness is used.
作者
蔡子颖
张敏
韩素芹
李培彦
刘敬乐
姚青
CAI Ziying;Zhang Min;HAN Suqin;Li Peiyan;Liu Jingle;YAO Qing(Tianjin Environmental Meteorological Center,Tianjin 300074;Tianjin Institute of Meteorology,Tianjin 300074)
出处
《气象》
CSCD
北大核心
2018年第7期911-920,共10页
Meteorological Monthly
基金
中国气象局预报员专项(CMAYBY2016-005和CMAYBY2017-006)
国家科技支撑计划(2014BAC16B04和2014BAC23B01)
天津市气象局课题(201716ybxm10)共同资助
关键词
天津
混合层厚度
污染天气分析
Tianjin
mixed layer thickness
pollution weather analysis
