Relationship of visibility, aerosol optical thickness and aerosol size distribution in an ageing air mass over South-West Germany
Relationship of visibility, aerosol optical thickness and aerosol size distribution in an ageing air mass over South-West Germany
复制标题
DOI：
10.1016/j.atmosenv.2007.10.017
复制
发表时间：
2008-02-01
影响因子：
5
通讯作者：
Schnaiter, M.
中科院分区：
文献类型：
--
作者：
Baeumer, D.;Vogel, B.;Schnaiter, M.
本文研究了德国西南部一个气团连续5天的老化过程。在这种情况下，对能见度、气溶胶粒径分布、气溶胶散射系数和相对湿度等气象变量进行了现场测量。此外，我们还测量了气溶胶柱特性，并提供了当地环保局附近站点的PM10质量浓度。从45到25公里的能见度明显下降，这是直接测量的两个独立的方法，一个显着的增加，PM 10，气溶胶光学厚度从0.1增加到0.6已被检测到。能见度下降与气溶胶数-谱分布的明显变化有关。在此期间，直径大于300 nm的颗粒数量大幅增加，而较小的颗粒则没有显示出如此明显的趋势。与气象范围的比较来自浊度计散射系数使用Koschmieder公式和湿度校正。通过与应用Mie理论扫描迁移率粒度仪（SMPS）/空气动力学粒度仪（APS）气溶胶粒度分布计算的气象范围进行比较，验证了散射比浊计测量的质量。计算出的气象范围与开始时测得的粒子数相比过高，而这种高估在更相对大的粒子丰富的时期结束时减少。我们的研究结果表明，一般缺乏代表性的水平平均参数作为观测能见度的现场测量。然而，当能见度降低时，这种代表性有所提高。此外，能见度和气溶胶光学厚度的一个明确的相互作用的行为已被发现。（c）2007年爱思唯尔有限公司保留所有权利。
The ageing process of an air mass over South-West Germany during 5 consecutive days has been examined. In-situ measurements of the visibility, aerosol size distributions, aerosol scattering coefficients and meteorological variables as relative humidity were measured during that situation. Additionally, we measured column aerosol properties, and PM10 mass concentrations of a nearby station of the local environmental protection agency were available. A distinct decrease in the visibility from 45 to 25 km, which was directly measured by two independent methods, a significant increase in PM 10, and an increase in the aerosol optical thickness from 0.1 to 0.6 have been detected. The visibility decrease is associated with distinct changes in the aerosol number-size distribution. The number of particles with diameters larger than 300 nm increased considerably during the period, whereas smaller particles did not show such a clear trend. A comparison with meteorological ranges derived from nephelometer scattering coefficients using the Koschmieder formula and a humidity correction is presented. The quality of the nephelometer measurements is verified by a comparison with meteorological ranges calculated from scanning mobility particle sizer (SMPS)/aerodynamic particle sizer (APS) aerosol size distributions applying Mie theory. The calculated meteorological ranges are too high in comparison with the measured visibilities in the beginning, whereas this overestimation decreases at the end of the period when more relatively large particles were abundant. Our results demonstrate the general lack of representativeness of an in-situ measurement for a horizontally averaged parameter as the observed visibility. However, this representativeness was improved when the visibility decreased. In addition, a clear reciprocal behaviour of the visibility and the aerosol optical thickness has been found. (c) 2007 Elsevier Ltd. All rights reserved.