Inferences from Simple Models of Slow, Convectively Coupled Processes
Inferences from Simple Models of Slow, Convectively Coupled Processes
复制标题
缓慢、对流耦合过程的简单模型的推论
DOI：
10.1175/jas-d-18-0090.1
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发表时间：
2019
影响因子：
3.1
通讯作者：
K. Emanuel
中科院分区：
文献类型：
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作者：
K. Emanuel
建立了一个用于理解慢的对流耦合扰动的概念框架，并将其应用于几个典型的热带问题，包括辐射-对流平衡中的大气水汽含量、对流降水与柱状水汽的关系、类Walker环流、对流的自聚集以及Madden-Julian振荡。该框架是对前人工作的综合，发展了四个关键近似：边界层能量准平衡、自由对流层湿和干静态能量守恒和弱温度梯度近似。结果表明，慢的对流耦合过程的基本特征可以在不参考复杂的湍流和微物理过程的情况下被理解，尽管考虑这种复杂性对于定量准确的建模是必不可少的。特别是，我们证明，在热带海洋上观测到的柱状水汽和降水之间的牢固关系并不一定意味着对流对自由对流层水分的直接敏感性。我们还表明，要破坏辐射-对流平衡状态，辐射与云和水汽之间的反馈必须相对于总的湿稳定性足够强。
A framework for conceptual understanding of slow, convectively coupled disturbances is developed and applied to several canonical tropical problems, including the water vapor content of an atmosphere in radiative–convective equilibrium, the relationship between convective precipitation and column water vapor, Walker-like circulations, self-aggregation of convection, and the Madden–Julian oscillation. The framework is a synthesis of previous work that developed four key approximations: boundary layer energy quasi equilibrium, conservation of free-tropospheric moist and dry static energies, and the weak temperature gradient approximation. It is demonstrated that essential features of slow, convectively coupled processes can be understood without reference to complex turbulent and microphysical processes, even though accounting for such complexity is essential to quantitatively accurate modeling. In particular, we demonstrate that the robust relationship between column water vapor and precipitation observed over tropical oceans does not necessarily imply direct sensitivity of convection to free-tropospheric moisture. We also show that to destabilize the radiative–convective equilibrium state, feedbacks between radiation and clouds and water vapor must be sufficiently strong relative to the gross moist stability.