Testing the performance of state-of-the-art dust emission schemes using DO4Models field data
Testing the performance of state-of-the-art dust emission schemes using DO4Models field data
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DOI：
10.5194/gmd-8-341-2015
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发表时间：
2015-01-01
影响因子：
5.1
通讯作者：
Menut, L.
中科院分区：
文献类型：
--
作者：
Haustein, K.;Washington, R.;Menut, L.
在沙尘观测模式（DO4Models）项目的框架内，本文利用一个箱型模式环境，对三种常用的沙尘排放方案的性能进行了研究。我们约束模型与现场数据（表面和灰尘颗粒特性以及气象参数）从一个干燥的湖床与结壳表面在博茨瓦纳在2011年的3个月期间。我们的箱模式结果表明，所有的方案未能再现所观察到的水平尘埃通量。他们把通量的大小高估了几个数量级。垂直尘埃排放通量的差异要小得多，尽管仍然高估了一个数量级。这种不匹配的关键参数是表面结皮，这限制了侵蚀性材料的可用性，即使在较高的风速下。第二个最重要的参数是土壤粒度分布。直接尘埃夹带推断是重要的几个灰尘事件，这解释了模拟和测量的垂直灰尘通量之间的差距较小。我们的结论是，这两个功能，结壳表面和直接夹带，需要纳入粉尘排放计划，以代表整个光谱的源过程。我们还得出结论，土壤水分施加关键控制的阈值剪切速度，从而在模式中的粉尘排放阈值。在野外，地壳状态是粉尘释放的控制机制。虽然结皮与土壤含水量有一定的相关性，但目前还不能推断出结皮状态与土壤含水量之间的强相关性。
Within the framework of the Dust Observations for Models (DO4Models) project, the performance of three commonly used dust emission schemes is investigated in this paper using a box model environment. We constrain the model with field data (surface and dust particle properties as well as meteorological parameters) obtained from a dry lake bed with a crusted surface in Botswana during a 3 month period in 2011. Our box model results suggest that all schemes fail to reproduce the observed horizontal dust flux. They overestimate the magnitude of the flux by several orders of magnitude. The discrepancy is much smaller for the vertical dust emission flux, albeit still overestimated by up to an order of magnitude. The key parameter for this mismatch is the surface crusting which limits the availability of erosive material, even at higher wind speeds. The second-most important parameter is the soil size distribution. Direct dust entrainment was inferred to be important for several dust events, which explains the smaller gap between modelled and measured vertical dust fluxes. We conclude that both features, crusted surfaces and direct entrainment, need to be incorporated into dust emission schemes in order to represent the entire spectra of source processes. We also conclude that soil moisture exerts a key control on the threshold shear velocity and hence the emission threshold of dust in the model. In the field, the state of the crust is the controlling mechanism for dust emission. Although the crust is related to the soil moisture content to some extent, we are not as yet able to deduce a robust correlation between state of crust and soil moisture.