A new process-based and scale-aware desert dust emission scheme for global climate models – Part II: Evaluation in the Community Earth System Model version 2 (CESM2)
A new process-based and scale-aware desert dust emission scheme for global climate models – Part II: Evaluation in the Community Earth System Model version 2 (CESM2)
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DOI：
10.5194/acp-24-2287-2024
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发表时间：
2024-02
影响因子：
6.3
通讯作者：
Danny M. Leung;J. Kok;Longlei Li;Natalie M. Mahowald;D. Lawrence;S. Tilmes;E. Kluzek;M. Klose;C. Pérez García-Pando
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作者：
Danny M. Leung;J. Kok;Longlei Li;Natalie M. Mahowald;D. Lawrence;S. Tilmes;E. Kluzek;M. Klose;C. Pérez García-Pando
摘要。沙漠沙尘是影响地球气候、生物地球化学和空气质量的重要大气气溶胶。然而，目前的地球系统模型（esm）很难准确地捕捉到尘埃对地球气候和生态系统的影响，部分原因是这些模型缺乏几个基本的风成过程，这些风成过程将尘埃与气候和陆地表面过程耦合起来。在本研究中，我们通过在社区地球系统模型第2版（CESM2）中详细介绍的几个新的风成过程参数化来解决这个问题。这些过程包括：(1)采用简化的土壤粒径表示来计算粉尘排放阈值摩擦速度，(2)考虑岩石和植被在减少可蚀性土壤风应力方面的阻力分配效应，(3)考虑由于未解决的湍流风波动而导致的粉尘排放间歇性。(4)对模拟沙尘排放的时空变异性进行从原生到高分辨率的修正。结果表明，与默认方案相比，改进的沙尘排放方案显著降低了模式对观测值的偏差，并提高了沙尘气溶胶光学深度（DAOD）、表面颗粒物浓度（PM）和沉降通量等多个关键沙尘变量与观测值的相关性。我们方案的沙尘也与各种气象和地面变量密切相关，这意味着沙尘对未来气候变化的敏感性高于其他方案的沙尘。这些发现强调了包括额外风成过程对改善ESM气溶胶模拟性能的重要性，并有可能加强对沙尘如何影响气候和生态系统变化的模式评估。
Abstract. Desert dust is an important atmospheric aerosol that affects the Earth's climate, biogeochemistry, and air quality. However, current Earth system models (ESMs) struggle to accurately capture the impact of dust on the Earth's climate and ecosystems, in part because these models lack several essential aeolian processes that couple dust with climate and land surface processes. In this study, we address this issue by implementing several new parameterizations of aeolian processes detailed in our companion paper in the Community Earth System Model version 2 (CESM2). These processes include (1) incorporating a simplified soil particle size representation to calculate the dust emission threshold friction velocity, (2) accounting for the drag partition effect of rocks and vegetation in reducing wind stress on erodible soils, (3) accounting for the intermittency of dust emissions due to unresolved turbulent wind fluctuations, and (4) correcting the spatial variability of simulated dust emissions from native to higher spatial resolutions on spatiotemporal dust variability. Our results show that the modified dust emission scheme significantly reduces the model bias against observations compared with the default scheme and improves the correlation against observations of multiple key dust variables such as dust aerosol optical depth (DAOD), surface particulate matter (PM) concentration, and deposition flux. Our scheme's dust also correlates strongly with various meteorological and land surface variables, implying higher sensitivity of dust to future climate change than other schemes' dust. These findings highlight the importance of including additional aeolian processes for improving the performance of ESM aerosol simulations and potentially enhancing model assessments of how dust impacts climate and ecosystem changes.