Cloud-Resolving Model Simulations with One- and Two-Way Couplings via the Weak Temperature Gradient Approximation
Cloud-Resolving Model Simulations with One- and Two-Way Couplings via the Weak Temperature Gradient Approximation
复制标题
通过弱温度梯度近似进行单向和双向耦合的云解析模型仿真
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
R. Plant
中科院分区：
文献类型：
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作者：
C. L. Daleu;S. Woolnough;R. Plant
为了模拟热带对流与大尺度热带环流之间的相互作用，本文对一个云分辨模式进行了改进，使其具有弱温度梯度近似。瞬时域平均位温放宽到从云解析模式的辐射对流平衡模拟获得的参考廓线。对于均匀表面条件，平衡时的模式状态是一个大尺度环流，其下降分支在模拟柱中。这与其他一些研究中发现的平衡状态相似，但不是所有研究。对于这个模型，这样的循环的发展是不敏感的松弛轮廓和初始条件。云解析模型的两列完全耦合，通过放松两列中的瞬时域平均位温彼此接近。与参比柱配置相比，该配置在能量上是闭合的。无论两柱的相对面积如何，在均匀的表面条件下，都不会产生平均的大尺度环流。如果两个模拟柱具有非常不同的面积，则对非均匀表面条件的灵敏度与参考柱配置中获得的灵敏度相似，但对于面积相当的柱，灵敏度明显较弱。较弱的灵敏度可以被理解为是能量预算关闭的制剂的结果。本文用参考柱位形研究了大尺度环流影响下的局部对流。扩展到一个两列配置提出了作为一种方法来研究远程对流的变化对本地对流的影响。
A cloud-resolving model is modified to implement the weak temperature gradient approximation in order to simulate the interactions between tropical convection and the large-scale tropical circulation. The instantaneous domain-mean potential temperature is relaxed toward a reference profile obtained from a radiative‐convective equilibrium simulation of the cloud-resolving model. For homogeneous surface conditions, the model state at equilibrium is a large-scale circulation with its descending branch in the simulated column. This is similar to the equilibrium state found in some other studies, but not all. For this model, the development of such a circulation is insensitive to the relaxation profile and the initial conditions. Two columns of the cloud-resolving model are fully coupled by relaxing the instantaneous domain-mean potential temperature in both columns toward each other. This configuration is energetically closed in contrast to the reference-column configuration. No mean large-scale circulation develops over homogeneous surface conditions, regardless of the relative area of the two columns. The sensitivity to nonuniform surface conditions is similar to that obtainedin the reference-column configuration if the twosimulated columnshave very different areas, but it is markedly weaker for columns of comparable area. The weaker sensitivity can be understood as being a consequence of a formulation for which the energy budget is closed. The referencecolumn configuration has been used to study the convection in a local region under the influence of a largescale circulation. The extension to a two-column configuration is proposed as a methodology for studying the influence on local convection of changes in remote convection.