Improved simulation of the polar atmospheric boundary layer by accounting for aerodynamic roughness in the parameterisation of surface scalar exchange over sea ice
Improved simulation of the polar atmospheric boundary layer by accounting for aerodynamic roughness in the parameterisation of surface scalar exchange over sea ice
复制标题
通过考虑海冰表面标量交换参数化中的空气动力学粗糙度，改进极地大气边界层的模拟
DOI：
10.1002/essoar.10512220.1
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Elvidge A
中科院分区：
文献类型：
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作者：
Elvidge A
一个新的，简单的参数化方案的标量（热量和水分）交换海冰和边缘冰区的数值天气和气候预报模式进行了测试。这个新的“混合A87”计划占的影响，空气动力学粗糙度的动量和标量交换之间的关系，在巩固海冰，符合长期的理论和最近的实地观察，并在目前的原油计划在大多数模式中运行。使用飞机观测和气象局统一模型模拟的冷空气爆发（CAO）条件下的空气动力学粗糙海冰，我们证明了显着的改善模型性能时，混合A87计划取代模型的业务处理表面标量交换，提供了空气动力学粗糙度超过巩固冰是适当的规定。地面感热通量、地面潜热通量、近地面气温和地面温度的平均偏差分别从25 ~ 11 W m-2、22 ~ 12 W m-2、0.8 ~ 0.0 K和1.4 ~ 0.8 K减小。我们表明，这种影响表面交换海冰可以有显着的影响，在模型中的CAO条件下，在数百公里的海冰顺风的大气边界层的演变。我们的研究结果突出了时空变化的重要性，在地形的巩固海冰的动量和标量交换海冰，占极地天气和气候建模仍然是一个挑战。
A new, simple parameterisation scheme for scalar (heat and moisture) exchange over sea ice and the marginal ice zone is tested in a numerical weather and climate prediction model. This new “Blended A87” scheme accounts for the influence of aerodynamic roughness on the relationship between momentum and scalar exchange over consolidated sea ice, in line with long-standing theory and recent field observations, and in contrast to the crude schemes currently operational in most models. Using aircraft observations and Met Office Unified Model simulations of cold-air outbreak (CAO) conditions over aerodynamically rough sea ice, we demonstrate striking improvements in model performance when the Blended A87 scheme replaces the model’s operational treatment for surface scalar exchange, provided that the aerodynamic roughness over consolidated ice is appropriately prescribed. The mean biases in surface sensible heat flux, surface latent heat flux, near-surface air temperature and surface temperature reduce from 25 to 11 W m-2, 22 to 12 W m-2, 0.8 to 0.0 K, and 1.4 to 0.8 K, respectively. We demonstrate that such impacts on surface exchange over sea ice can have a marked impact on the evolution of the atmospheric boundary layer across hundreds of kilometres downwind of the sea ice during CAO conditions in the model. Our results highlight the importance of spatiotemporal variability in the topography of consolidated sea ice for both momentum and scalar exchange over sea ice; accounting for which remains a challenge for modelling polar weather and climate.