A study on the sensitivities of simulated aerosol optical properties to composition and size distribution using airborne measurements
A study on the sensitivities of simulated aerosol optical properties to composition and size distribution using airborne measurements
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DOI：
10.1016/j.atmosenv.2014.02.063
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发表时间：
2014-06
影响因子：
5
通讯作者：
A. Esteve;E. Highwood;W. Morgan;G. Allen;H. Coe;R. Grainger;P. Brown;K. Szpek
中科院分区：
文献类型：
--
作者：
A. Esteve;E. Highwood;W. Morgan;G. Allen;H. Coe;R. Grainger;P. Brown;K. Szpek
我们提出了一个灵活的框架来计算大气气溶胶在给定相对湿度下的光学性质，基于它们的组成和大小分布。这一框架与气候模式参数化的相似性允许对数据中的不确定性或对与气候有关的气溶胶特性的新测量的影响进行快速和广泛的敏感性测试。FAAM BAe-146飞机在EUCAARI-LONGREX和VOCALS-REx活动期间收集的数据已用于一项闭幕研究，以分析两种非常不同的气溶胶类型的计算和测量气溶胶光学特性之间的一致性。为EUCAARI-LONGREX飞行达成的协议在散射和吸收的测量不确定度范围内。然而，VOCALS-REx飞行的散射计算值和测量值之间的一致性很差。高浓度的硫酸盐是一种散射气溶胶，在可见光谱中没有吸收，这使得VOCALS-REx期间的吸收测量不可靠，因此无法对吸收进行封闭研究。计算的吸湿散射生长因子对EUCAARI-LONGREX和VOCALS-REx期间的测量值分别高估了~ 30%和~ 20%。我们还测试了计算的气溶胶光学性质对折射率、吸湿生长因子和气溶胶粒径分布不确定性的敏感性。散射计算中的最大不确定性来源是气溶胶大小分布（~ 35%），其次是有机气溶胶的假设吸湿生长因子（~ 15%），而吸收计算中的主要不确定性来源是有机气溶胶的折射率（28-60%），尽管我们预计黑碳折射率对于黑碳含量较高的气溶胶很重要。
We present a flexible framework to calculate the optical properties of atmospheric aerosols at a given relative humidity based on their composition and size distribution. The similarity of this framework to climate model parameterisations allows rapid and extensive sensitivity tests of the impact of uncertainties in data or of new measurements on climate relevant aerosol properties. The data collected by the FAAM BAe-146 aircraft during the EUCAARI-LONGREX and VOCALS-REx campaigns have been used in a closure study to analyse the agreement between calculated and measured aerosol optical properties for two very different aerosol types. The agreement achieved for the EUCAARI-LONGREX flights is within the measurement uncertainties for both scattering and absorption. However, there is poor agreement between the calculated and the measured scattering for the VOCALS-REx flights. The high concentration of sulphate, which is a scattering aerosol with no absorption in the visible spectrum, made the absorption measurements during VOCALS-REx unreliable, and thus no closure study was possible for the absorption. The calculated hygroscopic scattering growth factor overestimates the measured values during EUCAARI-LONGREX and VOCALS-REx by ∼30% and ∼20%, respectively. We have also tested the sensitivity of the calculated aerosol optical properties to the uncertainties in the refractive indices, the hygroscopic growth factors and the aerosol size distribution. The largest source of uncertainty in the calculated scattering is the aerosol size distribution (∼35%), followed by the assumed hygroscopic growth factor for organic aerosol (∼15%), while the predominant source of uncertainty in the calculated absorption is the refractive index of organic aerosol (28–60%), although we would expect the refractive index of black carbon to be important for aerosol with a higher black carbon fraction.