| Atmospheric boundary layer refers to the lower troposphere. It is the air layer whichis directly affected by the ground, and must passed through when exchanging substances, energy,heat and moisture between the surface on the earth and the free atmosphere. Regional responseto global change, the change of the surface and the impact of human activities on the climate, isalso achieved through the atmospheric boundary layer process. Beijing, the capital of China, itsenvironment and air quality of the merits are related to China’s international image. Detecting theatmospheric boundary layer in Beijing, the forecast of atmospheric environment in Beijing andthe atmospheric environment control of the total, is of vital significance. In this paper, using thedetection of atmospheric boundary layer in Beijing from January2014to December byMP-3000A microwave radiometer, and the parcel method to get the atmospheric boundary layerheight of the Beijing in2014; Combining the ground meteorological data and PM2.5massconcentration data, analyzed the change features of atmospheric boundary layer duringFebruary and October heavy haze period and the APEC time in Beijing; the correlation of theboundary layer height and mass concentration of PM2.5was studied; finally, A-value method wasused to estimate PM2.5of atmospheric environmental capacity in Beijing. The main conclusionsare as follows:(1) According to the statistics of the boundary layer height during the day and nightrespectively For12months in2014, the boundary layer height at night have not changed much,the average height164m in December was the lowest. The height in June was the highest, andits average height was289m, that showed the trend that the heights of both sides were low, themiddle was high; The boundary layer height at daytime changed more obviously, in the first halfof the year showed a trend of rising, increasing from500m in January to1596m in June, was inkeeping with the trend of the monthly average temperature variation. In July, he boundary layerheight suddenly dropped to824m, and in November and December was relatively higher, was1231m and927m respectively.(2) The wind speed were in a state of stillness and given priority to with the south windwhen the February and October heavy haze occurred; the average visibility was very low, not more than1.4km; the boundary layer was very low, the most atmosphere were in a stable state orfalse latent instability, at the same time, air relative humidity was at a higher level. Thedissipation of gray haze mostly result from the cleaning of strong north wind，at that time, theelevated atmospheric boundary layer was often not immediately, but there was a lag.(2) Air quality was in good condition during the APEC, the wind speed changed frequently,of which four days were more than4m/s, and given priority to with the north, northwest wind,the boundary layer was up to4000m above. To reduce the concentration of the pollutants in theatmosphere by artificial measures can be indirectly make the boundary layer elevate, in return, itcan reduce the concentration of the pollutants, which form a virtuous circle.(3) According to the statistical analysis of hourly PM2.5mass concentration, the distributionof hourly PM2.5mass concentration every month was rather changeable, from2μg/m3to671μg/m3after. From a monthly-average-concentration point of view, the lowest was in June2014,and the highest was in February2014. Statistics of PM2.5daily average concentration, the days ofthe primary standards was81d, the frequency was22.2%, and the secondary standard was177d,the frequency was48.5%, and the exceed standard of days was188d, the frequency was51.5%.(4) The correlation of the average boundary layer height of hours of an average and thePM2.5mass concentration of hours was extremely low, showing that the up and down of thePM2.5mass concentration result from a variety of factors, not totally or directly depend on thechange of the boundary layer height. The change of pollutant concentration have a relatively lagwhen the boundary layer height changes. The influence of the wind and the change of PM2.5hysteresis will seriously affect the correlation of the two. To reduce the influence of hysteresis,growth the average period, then can find, as the average time lengthened, the correlation of theaverage boundary layer height and the PM2.5mass concentration will be grow, the higher was themonthly average, then was weekly, daily and the last was hour. The monthly average correlationcoefficient is0.714.(5) It can be estimated that the atmospheric environmental capacity of PM2.5in Beijing is1.753×105t/a by A-value method on the basis of PM2.5pollutants and control target of theconcentration of the secondary standard of it. |
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