Development of aerosol activation in the double-moment Unified Model and evaluation with CLARIFY measurements
Development of aerosol activation in the double-moment Unified Model and evaluation with CLARIFY measurements
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DOI：
10.5194/acp-20-10997-2020
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发表时间：
2020-09
影响因子：
6.3
通讯作者：
H. Gordon;P. Field;S. Abel;P. Barrett;K. Bower;I. Crawford;Z. Cui;D. Grosvenor;A. Hill;Jonathan W. Taylor;J. Wilkinson;Huihui Wu;K. Carslaw
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作者：
H. Gordon;P. Field;S. Abel;P. Barrett;K. Bower;I. Crawford;Z. Cui;D. Grosvenor;A. Hill;Jonathan W. Taylor;J. Wilkinson;Huihui Wu;K. Carslaw
抽象的。在气候、天气预报或空气质量模型中独立表示云和气溶胶颗粒的数量和质量对于模拟气溶胶对辐射平衡的直接和间接影响非常重要。在这里，我们介绍英国气象局统一模型的第一个配置，其中云和气溶胶粒子都具有具有预测数量和质量的“双矩”表示。全球气溶胶过程模型 (GLOMAP) 气溶胶微物理方案已在哈德利中心全球环境模型版本 3 (HadGEM3) 气候配置中使用，与云气溶胶相互作用微物理 (CASIM) 云微物理方案耦合。我们在 2017 年热带南大西洋阿森松岛附近的 CLARIFY 飞机战役中定义的案例研究的高分辨率模拟中展示了新配置的性能。我们通过表示现有云滴对新气溶胶激活的影响来改进激活方案的物理基础，并且我们还讨论了未解决的垂直速度的影响。我们表明，在之前的研究中忽视这两种相互竞争的影响会导致补偿误差，但会导致实际的液滴浓度。虽然这些变化仅导致模型性能略有改善，但它们增强了我们对模型微物理代码模拟其设计所代表的气溶胶-云微物理相互作用的能力的信心。准确捕获这些相互作用对于模拟气溶胶对气候的影响至关重要。
Abstract. Representing the number and mass of cloud and aerosol particles independently in a climate, weather prediction or air quality model is important in order to simulate aerosol direct and indirect effects on radiation balance. Here we introduce the first configuration of the UK Met Office Unified Model in which both cloud and aerosol particles have “double-moment” representations with prognostic number and mass. The GLObal Model of Aerosol Processes (GLOMAP) aerosol microphysics scheme, already used in the Hadley Centre Global Environmental Model version 3 (HadGEM3) climate configuration, is coupled to the Cloud AeroSol Interacting Microphysics (CASIM) cloud microphysics scheme. We demonstrate the performance of the new configuration in high-resolution simulations of a case study defined from the CLARIFY aircraft campaign in 2017 near Ascension Island in the tropical southern Atlantic. We improve the physical basis of the activation scheme by representing the effect of existing cloud droplets on the activation of new aerosol, and we also discuss the effect of unresolved vertical velocities. We show that neglect of these two competing effects in previous studies led to compensating errors but realistic droplet concentrations. While these changes lead only to a modest improvement in model performance, they reinforce our confidence in the ability of the model microphysics code to simulate the aerosol–cloud microphysical interactions it was designed to represent. Capturing these interactions accurately is critical to simulating aerosol effects on climate.