The role of deep convection and nocturnal low-level jets for dust emission in summertime West Africa: Estimates from convection-permitting simulations.
The role of deep convection and nocturnal low-level jets for dust emission in summertime West Africa: Estimates from convection-permitting simulations.
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夏季非洲夏季的深度对流和夜间低水平喷气机在尘埃排放中的作用：根据对流的模拟估计。
DOI：
10.1002/jgrd.50402
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发表时间：
2013-05-27
影响因子：
4.4
通讯作者：
Tegen, I.
中科院分区：
文献类型：
--
作者：
Heinold, B.;Knippertz, P.;Marsham, J. H.;Fiedler, S.;Dixon, N. S.;Schepanski, K.;Laurent, B.;Tegen, I.
关键词：
[1]对流冷池和夜间低空急流（NLLJ）的崩溃是夏季西非沙尘排放的关键气象驱动因素，西非是世界上最大的沙尘源。这项研究是第一项使用客观检测算法和应用于气象局统一模型中允许对流模拟的离线灰尘排放模型来量化它们的相对贡献和物理相互关系的研究。研究期为2006年7月25日至9月2日。因此，所有估计数可能会因年度而异。主要结论如下：（a）近40%的沙尘排放来自NLLJ，40%来自冷池，20%来自不明过程（B）一半以上的冷池排放与一种新发现的机制有关，即老冷池在夜间稳定层上方形成急流;（c）50%的沙尘排放发生在1500 - 0200 LT，最小值出现在日出前后和中午之后，早晨到中午的排放有60%发生在晴朗的天空下，但下午到夜间的排放只有10%，这表明卫星反演存在很大的偏差;（d）考虑到降水和土壤湿度的影响，冷池排放量减少了15%;（e）参数化对流模式显示冷池排放量大大减少，但NLLJ贡献较大。结果是更敏感的对流是否参数化或显式比选择的陆面表征，这通常是一个很大的不确定性来源。这项研究表明，真实地代表潮湿的对流和稳定的夜间条件的灰尘建模的需要。引文：Heinold，B.，P. Knippertz，J. H. Marsham，S. Fiedler，N. S.狄克逊，K. Schepanski，B.劳伦特和我。Tegen（2013），深对流和夜间低空急流对西非夏季沙尘排放的作用：对流允许模拟的估计，J. Geophys。剩余大气：118，4385-4400，doi：10.1002/jgrd.50402。
[1] Convective cold pools and the breakdown of nocturnal low-level jets (NLLJs) are key meteorological drivers of dust emission over summertime West Africa, the world’s largest dust source. This study is the first to quantify their relative contributions and physical interrelations using objective detection algorithms and an off-line dust emission model applied to convection-permitting simulations from the Met Office Unified Model. The study period covers 25 July to 02 September 2006. All estimates may therefore vary on an interannual basis. The main conclusions are as follows: (a) approximately 40% of the dust emissions are from NLLJs, 40% from cold pools, and 20% from unidentified processes (dry convection, land-sea and mountain circulations); (b) more than half of the cold-pool emissions are linked to a newly identified mechanism where aged cold pools form a jet above the nocturnal stable layer; (c) 50% of the dust emissions occur from 1500 to 0200 LT with a minimum around sunrise and after midday, and 60% of the morning-to-noon emissions occur under clear skies, but only 10% of the afternoon-to-nighttime emissions, suggesting large biases in satellite retrievals; (d) considering precipitation and soil moisture effects, cold-pool emissions are reduced by 15%; and (e) models with parameterized convection show substantially less cold-pool emissions but have larger NLLJ contributions. The results are much more sensitive to whether convection is parameterized or explicit than to the choice of the land-surface characterization, which generally is a large source of uncertainty. This study demonstrates the need of realistically representing moist convection and stable nighttime conditions for dust modeling. Citation: Heinold, B., P. Knippertz, J. H. Marsham, S. Fiedler, N. S. Dixon, K. Schepanski, B. Laurent, and I. Tegen (2013), The role of deep convection and nocturnal low-level jets for dust emission in summertime West Africa: Estimates from convection-permitting simulations, J. Geophys. Res. Atmos., 118, 4385–4400, doi:10.1002/jgrd.50402.
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影响因子：
6.3
作者：
Carslaw, K. S.;Boucher, O.;Kulmala, M.
通讯作者：
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DOI：
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发表时间：
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期刊：
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