【摘要】 利用2014—2016年四川盆地7个主要城市国家环境空气监测子站资料,结合2015—2016年MICAPS常规气象数据、NECP和ERA Interim再分析资料,统计分析四川盆地细颗粒物(PM_2.5)浓度时间分布特征及重污染期间的气象要素和环流背景.结果发现,2014—2016年四川盆地大气重污染主要发生在冬季,重污染日数分别为41、30和16 d,呈逐年降低的趋势.大气重污染期间,温度廓线出现多层逆温,逆温层大多出现在近地面925 hPa以下和700～600 hPa之间.四川盆地大气重污染主要对应两种环流形势,一种为500 hPa高空盛行西风气流,850 hPa高空等值线稀疏,另一种为四川盆地受到500 hPa高空槽后西北气流控制,地面为弱高压.以上两种环流形势下,四川盆地850 hPa高空附近气压梯度小,污染物不易扩散,导致重污染天气发生.本研究结论可为四川盆地大气重污染预报预警提供科学依据.更多还原

【Abstract】 The concentrations of fine particulate matters(PM_2.5) of 7 representative cities in the Sichuan Basin from 2014 to 2016, as well as the meteorological data of MICAPS, NECP and ERA Interim reanalysis data from 2015 to 2016, were used in the study to get deep insight into the variation of PM_2.5 concentrations in Sichuan Basin and the meteorological factors and circulation situations during the heavy pollutions. It revealed that most of the heavy pollution processes in Sichuan Basin occurred in winter. The number of heavy pollution days from 2014 to 2016 declined as 41, 30 and 16, respectively. Multi-inversion layers, which distributed in the layer of under 925 hPa near the surface and 700 ～600 hPa, were observed in most of the heavy pollution processes. There were two main patterns of the circulation situations during heavy pollutions in the Sichuan Basin, one was the west current prevailed in 500 hPa, while the contours were sparse in 850 hPa; the other one was the upper in 500 hPa of the Sichuan Basin controlled by the northwest air flow behind the trough, while the near ground controlled by the weak high-pressure system. Under the two patterns of circulation situations mentioned above, the pressure gradient at 850 hPa was weak, so that the pollutants were hard to disperse and then the heavy pollution occurred. The results might provide the scientific support to the forecast of the heavy pollutions.更多还原