Sensitivity of simulated wintertime Arctic atmosphere to vertical resolution in the ARPEGE/IFS model
Sensitivity of simulated wintertime Arctic atmosphere to vertical resolution in the ARPEGE/IFS model
复制标题
DOI：
10.1007/s00382-007-0316-z
复制
发表时间：
2008-06
期刊：
影响因子：
4.6
通讯作者：
Øyvind Byrkjedal;I. Esau;N. G. Kvamstø
中科院分区：
文献类型：
--
作者：
Øyvind Byrkjedal;I. Esau;N. G. Kvamstø
目前最先进的大气环流模式，包括IPCC使用的若干模式，与观测和再分析数据相比，在模拟当今高纬度气候方面显示出相当大的偏差。这些偏见在冬季最为明显。本文采用湍流解析模拟中温度和风的理想垂直剖面，对ARPEGE/IFS模型中采用的一阶涡粘闭合方案进行了先验研究。这表明，不能指望模式的粗垂直分辨率（31层）真实地解析北极稳定边界层。北极逆温的曲率以及垂直湍流交换过程不能用粗糙的垂直网格来再现。为了研究模式参数化如何表示北极边界层的湍流垂直交换过程，在对流层下层进行了高垂直分辨率（共90层）的模拟。模型模拟的结果与ERA-40再分析的数据进行了验证。研究了地面温度与地面风、地面能量通量、自由大气稳定性和边界层高度的关系。粗分辨率运行揭示了这些参数及其与地表空气温度的物理关系中存在相当大的偏差。在具有较好垂直分辨率的模拟中，这些偏差明显减小。与ERA-40数据相比，垂直湍流交换过程控制参数之间的物理关系有所改善。
The current state-of-the-art general circulation models, including several of those used by the IPCC, show considerable biases in the simulated present day high-latitude climate compared to observations and reanalysis data. These biases are most pronounced during the winter season. We here employ ideal vertical profiles of temperature and wind from turbulence-resolving simulations to perform a priori studies of the first-order eddy-viscosity closure scheme employed in the ARPEGE/IFS model. This reveals that the coarse vertical resolution (31 layers) of the model cannot be expected to realistically resolve the Arctic stable boundary layer. The curvature of the Arctic inversion and thus also the vertical turbulent-exchange processes cannot be reproduced by the coarse vertical mesh employed. To investigate how turbulent vertical exchange processes in the Arctic boundary layer are represented by the model parameterization, a simulation with high vertical resolution (90 layers in total) in the lower troposphere is performed. Results from the model simulations are validated against data from the ERA-40 reanalysis. The dependence of the surface air temperature on surface winds, surface energy fluxes, free atmosphere stability and boundary layer height is investigated. The coarse-resolution run reveals considerable biases in these parameters, and in their physical relations to surface air temperature. In the simulation with fine vertical resolution, these biases are clearly reduced. The physical relation between governing parameters for the vertical turbulent-exchange processes improves in comparison with ERA-40 data.