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首页> 外文期刊>Atmospheric chemistry and physics >Comparison of lidar-derived PMsub10/sub with regional modeling and ground-based observations in the frame of MEGAPOLI experiment
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Comparison of lidar-derived PMsub10/sub with regional modeling and ground-based observations in the frame of MEGAPOLI experiment

机译：MEGAPOLI实验框架中激光雷达衍生的PM 10 与区域建模和地面观测的比较

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An innovative approach using mobile lidar measurements was implemented totest the performances of chemistry-transport models in simulating massconcentrations (PM10) predicted by chemistry-transport models. Aground-based mobile lidar (GBML) was deployed around Paris onboard a vanduring the MEGAPOLI (Megacities: Emissions, urban, regional and GlobalAtmospheric POLlution and climate effects, and Integrated tools forassessment and mitigation) summer experiment in July 2009. The measurementsperformed with this Rayleigh-Mie lidar are converted into PM10 profilesusing optical-to-mass relationships previously established from in situmeasurements performed around Paris for urban and peri-urban aerosols. Themethod is described here and applied to the 10 measurements days (MD). MD of1, 15, 16 and 26 July 2009, corresponding to different levels of pollutionand atmospheric conditions, are analyzed here in more details. Lidar-derivedPM10 are compared with results of simulations from POLYPHEMUS and CHIMEREchemistry-transport models (CTM) and with ground-based observations fromthe AIRPARIF network. GBML-derived and AIRPARIF in situ measurements have beenfound to be in good agreement with a mean Root Mean Square Error RMSE (and aMean Absolute Percentage Error MAPE) of 7.2 μg m?3 (26.0%) and8.8 μg m?3 (25.2%) with relationships assuming peri-urban andurban-type particles, respectively. The comparisons between CTMs and lidarat ~200 m height have shown that CTMs tend to underestimate wet PM10concentrations as revealed by the mean wet PM10 observed during the 10 MDof 22.4, 20.0 and 17.5 μg m?3 for lidar with peri-urbanrelationship, and POLYPHEMUS and CHIMERE models, respectively. This leads to aRMSE (and a MAPE) of 6.4 μg m?3 (29.6%) and 6.4 μg m?3 (27.6%)when considering POLYPHEMUS and CHIMERE CTMs, respectively. Wetintegrated PM10 computed (between the ground and 1 km above the groundlevel) from lidar, POLYPHEMUS and CHIMERE results have been compared andhave shown similar results with a RMSE (and MAPE) of 6.3 mg m?2 (30.1%)and 5.2 mg m?2 (22.3%) with POLYPHEMUS and CHIMERE whencomparing with lidar-derived PM10 with periurban relationship. The valuesare of the same order of magnitude than other comparisons realized inprevious studies. The discrepancies observed between models and measuredPM10 can be explained by difficulties to accurately model the backgroundconditions, the positions and strengths of the plume, the vertical turbulentdiffusion (as well as the limited vertical model resolutions) andchemical processes as the formation of secondary aerosols. The majoradvantage of using vertically resolved lidar observations in addition tosurface concentrations is to overcome the problem of limited spatialrepresentativity of surface measurements. Even for the case of a well-mixedboundary layer, vertical mixing is not complete, especially in the surfacelayer and near source regions. Also a bad estimation of the mixing layerheight would introduce errors in simulated surface concentrations, which canbe detected using lidar measurements. In addition, horizontal spatialrepresentativity is larger for altitude integrated measurements than forsurface measurements, because horizontal inhomogeneities occurring nearsurface sources are dampened.
机译：实施了一种使用移动激光雷达测量的创新方法来测试化学运输模型在模拟化学运输模型预测的质量浓度（PM 10 ）中的性能。地面移动激光雷达（GBML）于2009年7月在MEGAPOLI（“大城市：排放，城市，区域和全球大气污染和气候影响以及用于评估和缓解的综合工具以及监测和缓解的综合工具”）巡回试验中，在巴黎周围部署。 -Mie激光雷达使用先前从巴黎周围对城市和近郊气溶胶进行的现场测量建立的光学质量关系，将其转换为PM 10 轮廓。该方法在此处进行了描述，并应用于10个测量日（MD）。此处详细分析了2009年7月1日，15日，16日和26日的MD，分别对应于不同程度的污染和大气状况。将激光雷达衍生的PM 10 与POLYPHEMUS和CHIMEREchemistry-transport模型（CTM）的模拟结果以及AIRPARIF网络的地面观测结果进行了比较。已发现GBML和AIRPARIF的原位测量与7.2μgm 3 （26.0％）和8的均方根均方根误差RMSE（和均值绝对百分比误差MAPE）非常吻合。 8μgm ？3 （25.2％）分别与假定城市周围和城市类型的颗粒有关。 CTM和激光雷达〜200 m高度之间的比较表明，CTM倾向于低估湿PM 10 的浓度，这是通过22.4的10 MD观测到的平均湿PM 10 所揭示的，具有城市周边关系的激光雷达分别为20.0和17.5μgm ？3 ，以及POLYPHEMUS和CHIMERE模型。当考虑使用POLYPHEMUS和CHIMERE CTM时，RMSE（和MAPE）分别为6.4μgm 3 （29.6％）和6.4μgm ？3 （27.6％）。分别。由激光雷达，POLYPHEMUS和CHIMERE计算得出的Wetintegrated PM 10 （在地面和地面以上1 km之间）的结果进行了比较，并且显示出类似的结果，RMSE（和MAPE）为6.3 mg m 与激光雷达衍生的具有城郊关系的PM 10 相比，？2 （30.1％）和5.2 mg m ？2 （22.3％）与POLYPHEMUS和CHIMERE相比。该值与先前研究中实现的其他比较具有相同的数量级。难以准确建模背景条件，羽流的位置和强度，垂直湍流扩散（以及有限的垂直模型分辨率）和化学过程的困难可以解释模型与实测PM 10 之间观察到的差异。二次气溶胶的形成。除了表面浓度以外，使用垂直分辨的激光雷达观测的主要优点是克服了表面测量空间代表性有限的问题。即使对于边界层充分混合的情况，垂直混合也不完整，特别是在表层和源区附近。同样，对混合层高度的错误估计也会在模拟表面浓度中引入误差，可以使用激光雷达测量来检测出误差。另外，高度集成测量的水平空间代表性要比表面测量的大，这是因为阻尼在地表源附近发生的水平不均匀性。

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