大气消光系数垂直分布模型及其适用性研究

The vertical distribution models of atmospheric extinction coefficient and their applicability

大气消光系数垂直分布模型是利用卫星反演近地面颗粒物质量浓度的关键技术环节,同时也是分析边界层湍流场结构的重要途径,但其适用性问题至今尚不清晰.基于Logistic曲线模拟大气消光系数廓线的初步研究成果,结合太阳光度计(CE-318)观测的大气光学厚度(AOD)资料以及近地面能见度数据,提出了大气消光系数垂直分布Logistic模型的参数计算方法.针对成都市2013年6月~2014年5月期间的实例应用结果表明,在不稳定和中性层结条件下,Logistic模型和目前通用的负指数模型对大气消光系数垂直分布的模拟效果总体相当;但在持续稳定层结条件下,Logistic模型的模拟效果则显著占优.进一步分析指出,大气消光系数垂直分布Logistic模型更优的适用性主要在于其对近地层大气消光的复杂垂直形态具有良好的表征能力.

Vertical distribution model of atmospheric extinction coefficient is a key technique for satellite inversion of near-surface particle mass concentration,and an important approach to analyze the structure of turbulent field in the boundary layer as well.However,there still exists much uncertainty in its applicability so far.In this study,a new method to calculate the parameters of Logistic profile model of atmospheric extinction coefficient was proposed.This method was based on the preliminary research of Logistic curve to simulate atmospheric extinction coefficient profile,and combined with atmosphere optical depth(AOD)data from the solar photometer(CE-318)as well as ground visibility data.The application results using the data from June 2013 to May 2014 in Chengdu showed that under unstable and neutral conditions,simulated results of atmospheric extinction coefficient by Logistic model and the currently widely used negative exponential model had considerable agreement.Under continuously stable conditions,simulated results obtained by the former were obviously better than those of the latter.Further analysis indicated that the applicability of Logistic vertical distribution model mainly lied in its excellent ability to simulate the complex vertical forms of atmospheric extinction coefficient in near surface layer.