长江三角洲地区冬季能见度特征及影响因子分析

利用Micaps提供的2013和2014年冬季长江三角洲地区(以下简称长三角)28个站点的地面常规观测资料、NCEP FNL再分析资料和国家环境保护部发布的PM_2.5质量浓度自动检测数据,分析了长三角冬季大气能见度特征,以及空气污染物和气象条件对能见度的影响.2013年冬季长三角霾天发生频率为53.4%.多元非线性回归分析表明,PM_2.5质量浓度、地表10m风速、500~850hPa水平风垂直切变、相对湿度、925~1000hPa垂直温差、850~925hPa假相当位温差这6个因子能够解释能见度变化的81.6%.气象条件对能见度的作用与污染物浓度相当,热力因子的贡献大约是动力因子的2倍.PM_2.5质量浓度越低,空气质量越好,以及相对湿度大于70%时,相对湿度通过气溶胶吸湿增长对能见度的作用越强.考虑PM_2.5质量浓度的影响时,相对湿度对能见度的贡献提高了1倍.利用2014年冬季资料验证多元拟合方程,效果较好.

Analysis of visibility characteristics and connecting factors over the Yangtze River Delta Region during winter time

Based on the meteorological data from 28 observation stations in winter 2013 and 2014, NCEP FNL reanalysis data and ground PM_2.5 observations, the characteristic of visibility and its relationship with air pollutants and meteorological conditions in the Yangtze River Delta in winter were analyzed. In winter 2013, the frequency of haze day was 53.4%. 81.6% of the visibility change can be explained by PM_2.5 concentration, 10m wind speed, wind shear (500~850hPa), relative humidity, temperature difference (925~1000hPa), potential pseudo-equivalent temperature difference (850~925hPa). The effects of meteorological conditions and air pollutants on visibility were comparable, and the contribution of thermal factor was almost twice that of dynamical factor. The RH impact on visibility was stronger at lower PM_2.5 concentration and higher RH (>70%). The visibility in winter 2014 was well reproduced by the nonlinear regression equation.