摘要
研究表明东亚地区严重的近地层空气污染与高空急流之间存在着一定的联系。本文利NCEP/NCAR逐日风场、垂直速度资料以及Science Data Bank的地面污染物和气象要素数据,运用统计分析法研究了冬季东亚高空急流与近地面空气污染物高浓度区的关系并初步探讨了两者之间的作用机制。结果表明,2013~2018年冬季我国华北平原是颗粒物的高值区,华北平原污染物PM_(2.5)、PM_(10)的平均浓度分别为80.65μg m^(−3)、118.62μg m^(−3),超标天数分别共计459 d、489 d。颗粒物浓度均呈逐年缓慢下降趋势,PM_(2.5)/PM_(10)平均浓度约为0.65,该比值保持多年稳定。该地区的空气污染物浓度与东亚高空温带急流和副热带急流之间的强度反位相变化关系显著,两者可能通过地面温度以及经向风进而产生联系。当冬季高空温带急流强度偏强时,平均状态下副热带急流强度会偏弱,温带急流与副热带急流之间通过次级环流进行质量交换并稳定在这一状态,此时由于华北平原处于减弱的副热带急流右侧,上升气流减弱,地面温度升高,有增强的异常南风出现,有利于华北平原中部的PM_(10)、北部PM_(2.5)的堆积。反之,当冬季高空温带急流强度偏弱时,平均状态下副热带急流强度会偏强,此时上升气流增强,地面温度降低,有减弱的异常北风出现,此时不利于华北平原中部的PM_(10)、北部PM_(2.5)的堆积。
Studies have reported a certain relationship between severe near-surface air pollution in East Asia and the upper jet.This paper investigates the relationship between the East Asian jet along with related mechanisms and high-concentration air pollutants near the ground during winter through statistical analysis based on daily wind field,vertical velocity data,and ground pollutant from NCEP/NCAR,and meteorological element data from the Science Data Bank.The results indicate that the concentrations of particulate matter in the North China Plain were considerably higher in winter during 2013–2018.The average concentrations of PM_(2.5)and PM_(10)in the North China Plain were 80.65μg m^(−3)and 118.62μg m^(−3),respectively.The number of days exceeding environmental standards reached 459 d and 489 d for PM_(2.5)and PM_(10),respectively.The concentration of particulate matter showed a gradual downward trend over the years with an average PM_(2.5)/PM_(10)ratio(about 0.65),which remained stable for several years.The concentration of air pollutants in the North China Plain has a significant relationship with the inverse phase variation of the intensity of the East Asian polar front and subtropical jets.This relationship may be influenced by the ground temperature and meridional wind.When the polar front jet is stronger in winter,the average intensity of the subtropical jet decreases,and the mass exchange between the two jets occurs through secondary circulation and is stabilized.North China Plain is present on the right side of the weakened subtropical jet,the updraft continues to weaken,the temperature rises,and enhanced anomalous southerly winds appear.These conditions are conducive to the accumulation of PM_(10)in the central part of the North China Plain and PM_(2.5)in the northern part of the North China Plain.When the polar front jet is weaker in winter,the strength of the subtropical jets in the mean state will be stronger,at which time the updraft is enhanced,the surface temperature is lowered,and there are weakened anomalous northerly winds appearing,which is unfavorable for PM_(10)in the central part of the North China Plain,and PM_(2.5)buildup in the northern part of the North China Plain at this time.
作者
魏雯
庄炳亮
蔺惠娟
束宇
王体健
陈慧敏
高伊曼
WEI Wen;ZHUANG Bingliang;LIN Huijuan;SHU Yu;WANG Tijian;CHEN Huimin;GAO Yiman(School of Atmosphefic Sciences,Nanjing University,Nanjing 210023;Nanjing Meteorological Bureau,Nanjing 210019)
出处
《大气科学》
CSCD
北大核心
2023年第5期1341-1354,共14页
Chinese Journal of Atmospheric Sciences
基金
国家重点研究发展计划项目2019YFA0606803
国家自然科学基金项目42075099、41675143、42077192、41621005
中央高校基本科研基金项目020714380169。
关键词
东亚高空急流
大气颗粒物
地面气象要素
统计分析
East Asian upper jet
Atmospheric particulate matter
Surface meteorological elements
Statistical analysis