A review of sea-spray aerosol source functions using a large global set of sea salt aerosol concentration measurements
A review of sea-spray aerosol source functions using a large global set of sea salt aerosol concentration measurements
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DOI：
10.5194/acp-14-1277-2014
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发表时间：
2014-01-01
影响因子：
6.3
通讯作者：
Stohl, A.
中科院分区：
文献类型：
--
作者：
Grythe, H.;Strom, J.;Stohl, A.
海洋喷雾气溶胶（SSA）是气候系统的重要组成部分，因为它们对全球辐射收支的影响-直接作为太阳和陆地辐射的散射体和吸收体，间接作为云凝结核（CCN）影响云的形成，寿命和降水。就其全球质量而言，SSA在所有气溶胶中具有最大的不确定性。在这项研究中，我们回顾了文献中的21个SSA源函数，其中几个用于当前的气候模式。此外，我们提出了一个新的功能。即使排除异常值，对于干直径D-p < 10 μ m的粒子，对于不同的源函数，全球每年产生的SSA质量跨度约为3-70 Pg yr（-1），对于给定的函数，年际变化相对较小。FLEXPART拉格朗日粒子扩散模型是在一个大型的全球观测到的SSA浓度，包括几个站网络和船舶巡航测量活动的落后模式运行。FLEXPART向后计算产生网格化的排放敏感性场，随后可以将其与网格化的SSA产生通量相乘，以获得模拟的SSA浓度。这使我们能够有效地同时评估所有21个源函数对测量。这种方法的另一个优点是，源区域的风速和海面温度（SST）的信息可以存储和用于改进SSA源函数参数化。最好的源函数再现高达70%的观测到的SSA浓度的变化在几个站，这是与“最先进的”气溶胶模型。SSA产生的主要驱动力是风，我们发现，当SSA产生与U-10（3.5）成正比时，可以获得与观测数据的最佳拟合，其中U-10是源区平均10米风速。SST对SSA生产的强烈影响，较高的温度导致较高的生产，也可以检测到，尽管SST影响的基本物理机制尚不清楚。我们的新的源函数与风速和温度的依赖性给出了一个全球SSA生产小于D-p < 10 μ m的粒子的9 Pg yr（-1），是最适合的观测浓度。
Sea-spray aerosols (SSA) are an important part of the climate system because of their effects on the global radiative budget - both directly as scatterers and absorbers of solar and terrestrial radiation, and indirectly as cloud condensation nuclei (CCN) influencing cloud formation, lifetime, and precipitation. In terms of their global mass, SSA have the largest uncertainty of all aerosols. In this study we review 21 SSA source functions from the literature, several of which are used in current climate models. In addition, we propose a new function. Even excluding outliers, the global annual SSA mass produced spans roughly 3-70 Pg yr(-1) for the different source functions, for particles with dry diameter D-p < 10 mu m, with relatively little interannual variability for a given function. The FLEXPART Lagrangian particle dispersion model was run in backward mode for a large global set of observed SSA concentrations, comprised of several station networks and ship cruise measurement campaigns. FLEXPART backward calculations produce gridded emission sensitivity fields, which can subsequently be multiplied with gridded SSA production fluxes in order to obtain modeled SSA concentrations. This allowed us to efficiently and simultaneously evaluate all 21 source functions against the measurements. Another advantage of this method is that source-region information on wind speed and sea surface temperatures (SSTs) could be stored and used for improving the SSA source function parameterizations. The best source functions reproduced as much as 70% of the observed SSA concentration variability at several stations, which is comparable with "state of the art" aerosol models. The main driver of SSA production is wind, and we found that the best fit to the observation data could be obtained when the SSA production is proportional to U-10(3.5), where U-10 is the source region averaged 10m wind speed. A strong influence of SST on SSA production, with higher temperatures leading to higher production, could be detected as well, although the underlying physical mechanisms of the SST influence remains unclear. Our new source function with wind speed and temperature dependence gives a global SSA production for particles smaller than D-p < 10 mu m of 9 Pg yr(-1), and is the best fit to the observed concentrations.