Evaluation of a reduced model for investigating hurricane formation from turbulence
Evaluation of a reduced model for investigating hurricane formation from turbulence
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DOI：
10.1002/qj.729
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发表时间：
2010-05
影响因子：
8.9
通讯作者：
D. Schecter
中科院分区：
文献类型：
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作者：
D. Schecter
本文评估了从湍流初始条件理解飓风形成的简化（三层）模型的充分性。评估是基于与采用单时刻暖雨微物理的云-系统-解析（CSR）模式中的热带气旋形成的直接比较。简化模型有三种积云参数化，即基于收敛（CB）、边界层准平衡（BLQ）和选择性升压（SB）选项。无论哪一个被激活，简化模型产生的飓风与CSR模型在相同的时间尺度上。一般来说，飓风是由湍流通过气旋涡度的合并和对流增强而产生的。此外，在简化模式和CSR模式中，“快速强化”的开始都伴随着Ooyama（1969）的η变量的显著局部增长，该变量是深层对流不稳定性和对流层中层湿度的综合测量。在两种模式中，消除湿熵的表面通量或表面摩擦可以防止或严重抑制飓风的形成；然而，在简化模型的BLQ或SB版本中，飓风最终在没有表面摩擦的情况下形成。
This paper evaluates the adequacy of a reduced (three‐layer) model for understanding hurricane formation from turbulent initial conditions. The evaluation is based on a direct comparison to tropical cyclogenesis in a cloud‐system‐resolving (CSR) model that employs single‐moment warm rain microphysics. The reduced model has three cumulus parametrizations, referred to as the convergence‐based (CB), boundary layer quasi‐equilibrium (BLQ), and selective boost (SB) options. Regardless of which one is activated, the reduced model produces hurricanes on the same time‐scale as the CSR model. Generally speaking, the hurricanes emerge from turbulence through the coalescence and convective intensification of cyclonic vorticity. Moreover, in both the reduced and CSR models, the onset of ‘rapid intensification’ follows pronounced local growth of the η‐variable of Ooyama (1969), which is a combined measure of deep convective instability and middle tropospheric moisture. Eliminating the surface flux of moist entropy or surface friction in either model prevents or severely inhibits hurricane formation; however, hurricanes eventually form without surface friction in the BLQ or SB versions of the reduced model.