An Improved Framework for Superparameterization.
An Improved Framework for Superparameterization.
复制标题
改进的超参数化框架。
DOI：
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发表时间：
2004
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通讯作者：
W. Grabowski
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作者：
W. Grabowski
本文讨论了一个大规模的模式系统，显式表示的小尺度和中尺度过程所提供的云解析模式嵌入在每列的大规模模式，超参数化。在原来的配方，被称为云解析对流参数化（CRCP），热力学变量耦合使用适当的平均程序，但水平动量耦合只通过松弛的方法。改进后的系统是基于两个模型之间的耦合的一般公式，并放弃了松弛技术。一个简单的，但强大的时间积分方案的系统开发使用无振荡的时间向前的方法，适用于大尺度和云尺度模式。改进的公式适用于问题，以前研究的作者，大规模组织赤道对流的旋转恒定海表面温度（SST）aquaplanet对流辐射准平衡。三个模拟使用2D小规模的模型，在原来的CRCP方法。在前两个模拟中，2D模型具有分区方向。第一个模拟在物理设置中应用新的耦合方案，该方案不包括表面阻力。大尺度和小尺度水平动量之间的紧密耦合导致了Madden-Julian振荡（MJO）的快速组织，如相干结构和强超旋转的发展。在第二个模拟中，表面阻力被添加到2D小尺度模型物理中。这导致了类似MJO的相干结构的发展，与陆地MJO相比，具有弱的超旋转和更真实的西风爆发强度。第三次模拟中还包括表面阻力，其中耦合以这样一种方式制定，即二维小尺度模型域的方向是沿着低对流层风，因此它在空间和时间上是变化的。第三次模拟的结果在性质上类似于小尺度模型的表面阻力和纬向方向的模拟。
This paper discusses a large-scale modeling system with explicit representation of small-scale and mesoscale processes provided by a cloud-resolving model embedded in each column of a large-scale model, the superparameterization. In the original formulation, referred to as the cloud-resolving convection parameterization (CRCP), thermodynamic variables were coupled using appropriate averaging procedure, but horizontal momenta were coupled only through the relaxation approach. The improved system is based on the general formulation of the coupling between the two models, and the relaxation technique is abandoned. A simple but robust time integration scheme for the system is developed using the nonoscillatory forward-in-time approach applied in both the large-scale and cloud-scale models. The improved formulation is applied to the problem, previously studied by the author, of large-scale organization of equatorial convection on a rotating constant sea surface temperature (SST) aquaplanet in convective‐ radiative quasi equilibrium. Three simulations are performed using 2D small-scale models as in the original CRCP approach. In the first two simulations, the 2D models have zonal orientation. The first simulation applies the new coupling scheme in the physical setup, which does not include surface drag. Tight coupling between large-scale and small-scale horizontal momenta results in rapid organization of Madden‐Julian oscillation (MJO)like coherent structures and development of strong superrotation. In the second simulation, surface drag is added into 2D small-scale model physics. This results in the development of MJO-like coherent structures with weak superrotation and more realistic strength of the westerly wind burst when compared to the terrestrial MJO. Surface drag is also included in the third simulation, where the coupling is formulated in such a way that orientation of 2D small-scale model domains is along the lower-tropospheric winds and thus it varies in space and time. Results from the third simulation are qualitatively similar to the simulation with surface drag and zonal orientation of small-scale models.