A new sub-grid scale lift formulation in a mountain drag parameterisation scheme
A new sub-grid scale lift formulation in a mountain drag parameterisation scheme
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山地阻力参数化方案中新的子网格尺度升力公式
DOI：
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发表时间：
2008
期刊：
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通讯作者：
R. Mládek
中科院分区：
文献类型：
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作者：
B. Catry;J. Geleyn;F. Bouyssel;J. Cedilnik;R. Brožková;M. Derková;R. Mládek
本文提出了一种新的亚网格尺度升力公式，用于山区阻力参数化方案。主要的新奇是一种新的方法，使升力作用于地转风矢量的估计（而不是作用于当地近地面风矢量）。这种新的公式的目标是避免包络地形，否则仍然需要在ALADIN/ARPEGE数值天气预报（NWP）模式。在ARPEGE/ALADIN参数化中，对亚网格尺度地形影响的新升力公式的验证在三个预测尺度上进行：（1）ALADIN对复杂地形上的理想流进行半理想化试验，以产生动量收支;（2）使用ALADIN的中欧业务版本进行区域尺度试验，以产生中欧的验证分数;以及（3）使用ARPEGE-NWP模型的全球尺度检验，以在不同大陆上呈现统计上显著的分数。新的升力公式能够模拟由于包络地形导致的风向的额外变化，同时避免其不利影响，例如对模拟降水的影响。更新的参数化方案已成为独立的分辨率和参数化的影响消失之间的某个地方的水平网格大小为2.5和5公里。最后，在ARPEGE/ALADIN系统中演示了新方案的操作性能。
A new sub-grid scale lift formulation in a mountain drag parameterisation scheme is presented. The main novelty is a new approach to make the lift force act on an estimate of the geostrophic wind vector (instead of acting on the local near-surface wind vector). The goal of this new formulation is to avoid the envelope orography which is otherwise still needed in the ALADIN/ARPEGE Numerical Weather Prediction (NWP) model. The validation of this new lift formulation inside the ARPEGE/ALADIN parameterisation for sub-grid scale orographic effects takes place on three prediction scales with their proper tools: (1) semi-idealised tests performed by ALADIN on an idealised flow over a complex orography to yield momentum budgets; (2) regional scale tests using the operational Central European version of ALADIN to produce verification scores over Central Europe; and (3) global scale tests using the ARPEGE-NWP model to render statistically significant scores over the different continents. The new lift formulation is able to mimic the additional change in wind direction due to an envelope orography, while avoiding its unfavourable effects e.g. on the simulated precipitation. The updated parameterisation scheme has become resolution independent and the impact of the parameterisation disappears somewhere between a horizontal mesh size of 2.5 and 5 km. Finally, the operational performance of the new scheme in the ARPEGE/ALADIN system is demonstrated.