Convective boundary layer evolution from lidar backscatter and its relationship with surface aerosol concentration at a location of a central China megacity

被引:39
作者
Kong, Wei [1 ,2 ,3 ]
Yi, Fan [1 ,2 ,3 ]
机构
[1] Wuhan Univ, Sch Elect Informat, Wuhan 430072, Peoples R China
[2] Minist Educ, Key Lab Geospace Environm & Geodesy, Wuhan, Peoples R China
[3] State Observ Atmospher Remote Sensing, Wuhan, Peoples R China
基金
中国国家自然科学基金;
关键词
convective boundary layer; evolution; lidar backscatter; aerosol; optical particle counter; OPTICAL-PROPERTIES; RAMAN LIDAR; DEPTH VARIABILITY; SAHARAN DUST; HEIGHT; AFTERNOON; RADIOSONDE; IMPACT; RETRIEVALS; TRANSITION;
D O I
10.1002/2015JD023248
中图分类号
P4 [大气科学(气象学)];
学科分类号
0706 ; 070601 ;
摘要
Based on the 1min backscatter ratio R profiles from the all-day lidar measurements in Wuhan, China (30.5 degrees N, 114.4 degrees E), hourly convective boundary layer (CBL) height was calculated with the variance method. The calculated CBL height sequence displays the regular diurnal cycle of the CBL top. The prevalent mixing process within the CBL is also revealed. During the CBL growth period, the backscatter ratio R falls visibly with increasing altitude and has large variance within the CBL, suggesting that more abundant aerosol particles from lower altitudes are being transported upward and being mixed with the local background or advected aerosol layers. During the CBL quasistationary period, R tends to be vertically uniform, and its variance reaches a daytime minimum within the CBL, indicating that the vertical homogenization of aerosol particles produced by the convectively driven mixing reaches its maximum. During the afternoon and early evening transition period, the vertical uniformity of R weakens and the variance enlarges again, implying that the reduced convectively driven mixing fails to maintain a high vertical homogeneity. When the 1min R profiles were plotted together in terms of each 1h interval, the fluctuating R curves at heights around the CBL top looked like a node, representing the structure of the entrainment zone between the CBL and the free troposphere. The moving node depicts the evolution of the entrainment zone. The diurnal variation of the CBL height shows an obvious seasonal dependence which coincides with the annual variation of the local surface temperature. The surface fine particle concentration generally has a more complex diurnal cycle than that expected from the CBL-dilution/CBL-accumulation effect. But, it shows a strong annual variation which is out of phase with respect to that of the monthly mean maximum CBL height. This tends to suggest that the seasonal behavior of the surface fine particle concentration mainly depends on the seasonal variation in available volume (determined by the CBL height) for aerosol dispersion.
引用
收藏
页码:7928 / 7940
页数:13
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