三种激光雷达监测污染物分布和输送对比
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摘要
利用3种不同型号激光雷达在广州番禺大气成分观测站开展外场同步对比观测实验.通过全球地基气溶胶监测网(AERONET)气溶胶光学厚度(AOD)产品验证了3种激光雷达原始信号反演消光系数的可靠性.同时对比探讨了激光雷达低层反演能见度产品与能见度仪的相关性;对比美国国家环境预报中心全球同化系统模式(NCEP-GDAS)模拟结果讨论了激光雷达对混合层高度反演的有效性.最后利用个例分析揭示不同天气型下污染物可能的外源输送和本地积累.量化分析结果表明:3部激光雷达反演的能见度与能见度仪的相关系数均达到0.7以上,混合层高度均与NCEP-GDAS模式计算的混合层高度具有一定的可比性.与模拟结果相比,白天混合层高度在霾天气时相对较低,更能有效的揭示霾天气,亦可反映夜间间歇性湍流特性.应用分析表明:3部激光雷达均能较为一致的监测污染物的输送和本地的累积.外来输送主要以弱冷空气输送型为例,分析个例(2014年11月21~22日、24~25日)表明:后一过程(24~25日)由于夜间混合层高度(MLH)低,导致上层的粒子无法下传,污染物聚集在0.8km,且快速过境了,而前一过程(21~22日)整层输送,导致了近地层相对高的PM_(2.5)浓度;本地累积主要以冷高出海型为例(2014年11月25日20:00~27日20:00),逆温与低的地表通风系数共同造成了前一时段(25日20:00~26日20:00)的消光明显高于后一时段(26日20:00~27日20:00).
This study aerosol extinction profiles at Guangzhou were measured with three commercially available lidars which were collocated at Guangzhou Panyu site. The measurement was carried out from November 17 through November 30, 2014. The AOD(aerosol optical depth) retrieved from different instruments were highly correlated with that from AERONET(aerosol robotic network), and the retrieved and measured surface extinction coefficient provided comparable results(R>0.7), indicating that the algorithm for the extinction coefficient profiles is reliability. Also, the retrieved MLH(mixing layer height) was compared with model results from National Centers for NCEP-GDAS(environmental prediction global data assimilation system). The results showed that the MLH from the three types of lidar were consistent with that of the NCEP-GDAS model, but the model result had no obvious response to the intermittent turbulent mixing at night, suggesting that the lidar result was more effective for the inversion of MLH. Finally, several cases were analyzed to reveal the characteristics of pollution under different weather circulation types. Results show that the three lidars can be used to monitor the transport and local accumulation of pollutants consistently. Two cases under weak cold-air weather pattern(November 21~22, 24~25, 2014) serve as examples for pollutants transport. For the first case, particulates were trapped above 0.8 km and passed through the site quickly. For the second case, particulates were trapped whole layer,resulting high PM_(2.5) at surface layer. Under the weather pattern of the cold High pressure gone to sea, a local accumulation pollution episode(November 25~27, 2014) was studied. The result showed that thermal inversion layer and lower ventilation coefficient result in the higher extinction coefficient in November 26 than that in November 27.
This study aerosol extinction profiles at Guangzhou were measured with three commercially available lidars which were collocated at Guangzhou Panyu site. The measurement was carried out from November 17 through November 30, 2014. The AOD(aerosol optical depth) retrieved from different instruments were highly correlated with that from AERONET(aerosol robotic network), and the retrieved and measured surface extinction coefficient provided comparable results(R>0.7), indicating that the algorithm for the extinction coefficient profiles is reliability. Also, the retrieved MLH(mixing layer height) was compared with model results from National Centers for NCEP-GDAS(environmental prediction global data assimilation system). The results showed that the MLH from the three types of lidar were consistent with that of the NCEP-GDAS model, but the model result had no obvious response to the intermittent turbulent mixing at night, suggesting that the lidar result was more effective for the inversion of MLH. Finally, several cases were analyzed to reveal the characteristics of pollution under different weather circulation types. Results show that the three lidars can be used to monitor the transport and local accumulation of pollutants consistently. Two cases under weak cold-air weather pattern(November 21~22, 24~25, 2014) serve as examples for pollutants transport. For the first case, particulates were trapped above 0.8 km and passed through the site quickly. For the second case, particulates were trapped whole layer,resulting high PM_(2.5) at surface layer. Under the weather pattern of the cold High pressure gone to sea, a local accumulation pollution episode(November 25~27, 2014) was studied. The result showed that thermal inversion layer and lower ventilation coefficient result in the higher extinction coefficient in November 26 than that in November 27.
引文
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[20]Holben B N,Eck T F,Slutsker I,et al.AERONET-A federated instrument network and data archive for aerosol characterization[J].Remote Sensing of Environment,1998,66:1-16.
[21]Nakajima T,Tonna G,Rao R,et al.Use of sky brightness measurements from ground for remote sensing of particulate polydispersions[J].Applied Optics,1996,35:2672-2686.
[22]Dubovik O,King M D.A flexible inversion algorithm for retrieval of aerosol optical properties from sun and sky radiance measurements[J].Geophysical Research,2000,105:1072-1087.
[23]Eck T F,Holben B N,Dubovik O,et al.Wavelength dependence of the optical depth of biomass burning,urban and desert dust aerosols[J].Geophysical Research,1999,104,31:333-350.
[2]Olofson K F G,Andersson P U,Hallquist M,et al.Urban aerosol evolution and particle formation during wintertime temperature inversions[J].Atmospheric Environment,2009,43(2):340-346.
[3]Badarinath K V S,Kharol S K,Sharma A R.Long-range transport of aerosols from agriculture crop residue burning in Indo-Gangetic Plains—A study using LIDAR,ground measurements and satellite data[J].Journal of Atmospheric and Solar-Terrestrial Physics,2009,71(1):112-120.
[4]Lopes F J S,Landulfo E,Vaughan M A.Assessment of the CALIPSO Lidar 532nm version 3lidar ratio models using a ground-based lidar and AERONET sun photometers in Brazil[J].Atmospheric Measurement Techniques Discussions,2013,6(1):1143-1199.
[5]Welton E J,Voss K J,Quinn P K,et al.Measurements of aerosol vertical profiles and optical properties during INDOEX1999using micropulse lidars[J].Journal of Geophysical Research,2002,107(D19):8019-8041.
[6]Welton E J,K J Voss,Gordon H R,et al.Ground-based lidar measurements of aerosols during ACE-2:Instrument description,results,and comparisons with other ground-based and airborne measurements[J].Tellus,2000,(52B):636-651.
[7]Piironen A K,Eloranta E W.Convective boundary layer mean depths and cloud geometrical properties obtained from volume imaging lidar data[J].Journal of Geophysical Research,1995,100:25569-25576.
[8]Pahlow M,Kleissl J,Parlange M,et al.Atmospheric boundarylayer structure observed during a haze event due to forest-fire smoke[J].Boundary-Layer Meteorology,2005,114:53-70.
[9]贺千山,毛节泰.北京城市大气混合层与气溶胶垂直分布观测研究[J].气象学报,2005,63(3):374-384.
[10]贺千山.微脉冲激光雷达研究对流层气溶胶属性和分布特征[D].北京:北京大学,2006.
[11]潘鹄.利用微脉冲激光雷达研究上海灰霾气溶胶光学特性[D].上海:东华大学,2010
[12]邓涛,吴兑,邓雪娇,等.一次严重灰霾过程的气溶胶光线特性垂直分布[J].中国环境科学,2013,33(11):1779-1784.
[13]王耀庭,苗世光,张小玲.基于激光雷达的北京市气溶胶光学参数季节特征[J].中国环境科学,2016,36(4):970-978.
[14]吕阳,李正强,谢剑锋,等.基于激光雷达扫描观测的散布点污染源监测[J].中国环境科学,2017,37(11):4078-4084.
[15]Fernald F G.Analysis of atmospheric lidar observations:comments[J].Applied Optics,1984,23:652-653.
[16]Takamura T,Sasano Y.Ratio of aerosol backscatter to extinction coefficients as determined from angular scattering measurements for use in atmospheric lidar applications[J].Optical and Quantum Electronics,1987,19:293-302.
[17]Sasano Y,Nakane H.Significance of the extinction/backscatter ratio and the boundary value term in the solution for the twocomponent lidar equation[J].Applied Optics,1984,23(1):11-13.
[18]Sasano Y,Nakane H.Quantitative analysis of RHI lidar data by an iterative adjustment of the boundary condition term in the lidar solution[J].Applied Optics,1987,26(4):615-616.
[19]刘东.偏振-米(散射)激光雷达的研制和大气边界层的激光雷达探测[D].安徽:中国科学院安徽光学精密机械研究所,2005.
[20]Holben B N,Eck T F,Slutsker I,et al.AERONET-A federated instrument network and data archive for aerosol characterization[J].Remote Sensing of Environment,1998,66:1-16.
[21]Nakajima T,Tonna G,Rao R,et al.Use of sky brightness measurements from ground for remote sensing of particulate polydispersions[J].Applied Optics,1996,35:2672-2686.
[22]Dubovik O,King M D.A flexible inversion algorithm for retrieval of aerosol optical properties from sun and sky radiance measurements[J].Geophysical Research,2000,105:1072-1087.
[23]Eck T F,Holben B N,Dubovik O,et al.Wavelength dependence of the optical depth of biomass burning,urban and desert dust aerosols[J].Geophysical Research,1999,104,31:333-350.