Abstract: Using monitoring data of PM_2.5 in 2013 from 11 monitoring sites in Shenyang city,the distribution characteristics of PM_2.5 in years,months,days and hours were studied,and the correlations between PM_2.5 concentration and each of air temperature,ground temperature,humidity,wind speed,air pressure and precipitation were analyzed. The results showed that the PM_2.5 concentration of Zhangshi,Ermao and Taiyuanjie monitoring stations was relatively high throughout the year,and that of school of Artilley,Huishan monitoring point was relatively low. The monthly average PM_2.5 concentration value of each monitoring point was highest in January,the largest average daily concentration occurred in December. In winter,the daily and hourly change of PM_2.5 concentration was obvious. Wind speed had negative correlation with PM_2.5 concentration,while humidity,ground temperature,air temperature,air pressure, precipitation with PM_2.5 concentration had positive correlation. The weather situation of severe pollution in Shenyang city in December 22 was analyzed,the results indicate that it was the weak warm ridge in Liaoning province at 500 hPa geopotential height field. While it was influenced by divergence and downdraft at 850 hPa geopotential height field and the ground wind field,wind speed were small. In vertical wind field,the downdraft was obvious.Significant temperature inversion occurred on the temperature profile from the ground up to the high altitude. When the pollution was most severe,the boundary layer was at a low level.

Key words: PM_2.5, distribution characteristics, meteorological conditions, Shenyang city