A strategy for representing the effects of convective momentum transport in multiscale models: Evaluation using a new superparameterized version of the Weather Research and Forecast model (SP‐WRF)
A strategy for representing the effects of convective momentum transport in multiscale models: Evaluation using a new superparameterized version of the Weather Research and Forecast model (SP‐WRF)
复制标题
在多尺度模型中表示对流动量传输影响的策略：使用天气研究和预报模型 (SP-WRF) 的新超参数化版本进行评估
DOI：
10.1002/2014ms000417
复制
发表时间：
2015
影响因子：
6.8
通讯作者：
Stefan N. Tulich
中科院分区：
文献类型：
--
作者：
Stefan N. Tulich
本文描述了一种在大尺度动力学求解器中处理对流动量输运（CMT）的通用方法，该求解器使用循环二维（2-D）云解析模型（CRM）作为对流系统尺度过程的“超参数化”。该方法在概念上类似于CMT的传统参数化，但区别在于标量输运和诊断压力梯度力都是使用2-D CRM提供的信息计算的。因此，未对对流诱导的压力梯度力在产生上梯度或下梯度CMT中的作用进行假设。使用本文首次描述的天气研究和预报模型（SP-WRF）的新超参数化版本来评估所提出的方法。结果表明，该公式的净效应是通过“积云摩擦”适度降低大尺度环流的整体强度。除了真实的全球季节性（6月1日至8月31日）气候的模拟外，这一说法也适用于两种中尺度对流系统（飑线和热带气旋）的理想化模拟。在后者的情况下，包括公式被发现，以改善描述的关键天气模式的热带波变率，除了某些方面的模拟时间平均气候。还发现CRM方向的选择对模拟的时间平均气候有重要影响，这显然是由于广泛分布的浅对流区域的显式表示的变化。
This paper describes a general method for the treatment of convective momentum transport (CMT) in large‐scale dynamical solvers that use a cyclic, two‐dimensional (2‐D) cloud‐resolving model (CRM) as a “superparameterization” of convective‐system‐scale processes. The approach is similar in concept to traditional parameterizations of CMT, but with the distinction that both the scalar transport and diagnostic pressure gradient force are calculated using information provided by the 2‐D CRM. No assumptions are therefore made concerning the role of convection‐induced pressure gradient forces in producing up or down‐gradient CMT. The proposed method is evaluated using a new superparameterized version of the Weather Research and Forecast model (SP‐WRF) that is described herein for the first time. Results show that the net effect of the formulation is to modestly reduce the overall strength of the large‐scale circulation, via “cumulus friction.” This statement holds true for idealized simulations of two types of mesoscale convective systems, a squall line, and a tropical cyclone, in addition to real‐world global simulations of seasonal (1 June to 31 August) climate. In the case of the latter, inclusion of the formulation is found to improve the depiction of key synoptic modes of tropical wave variability, in addition to some aspects of the simulated time‐mean climate. The choice of CRM orientation is also found to importantly affect the simulated time‐mean climate, apparently due to changes in the explicit representation of wide‐spread shallow convective regions.