The Multiscale Impacts of Organized Convection in Global 2‐D Cloud‐Resolving Models
The Multiscale Impacts of Organized Convection in Global 2‐D Cloud‐Resolving Models
复制标题
全球二维云解析模型中组织对流的多尺度影响
DOI：
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发表时间：
2018
影响因子：
6.8
通讯作者：
Noah D. Brenowitz
中科院分区：
文献类型：
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作者：
Noah D. Brenowitz
本文利用在周期性二维32,000公里区域进行的三组云解析大气模拟，研究了热带潮湿对流多尺度组织背后的机制。在300.15 K的恒定海表温度下，表面通量和长波辐射相互作用的模拟经过80天的模拟，产生了一个行星尺度的自聚集对流斑块。将地表通量和辐射冷却固定在一个恒定的值会抑制这种行星尺度的组织。然而，通过增加平流层加热来增加对流层顶的稳定性，可以产生一个模拟结果，即在30天后产生一个行星尺度的波。这种行星尺度波调制向东传播的天气尺度波，而天气尺度波又调制向西传播的中尺度对流系统。低通滤波器用于诊断反馈，这些反馈会产生纬向速度、浮力和湿度的大尺度变化。行星尺度的浮力变化和纬向速度变化分别与有效势能（APE）和动能（KE）预算有关。在具有平流层加热的模拟中，行星尺度的KE由纬向动量的垂直通量产生，转化为APE，然后由潜热、混合和其他浮力源耗散。在没有平流层加热的情况下，这些反馈产生的KE在平流层中受到强烈的阻尼。在行星尺度上，纬向动量的中尺度涡旋通量辐合主导了总垂直通量反馈，其垂直结构与向西传播的中尺度对流系统一致。总的来说，这些结果表明，在没有其他非绝热反馈的情况下，这些涡旋通量可以在行星尺度上组织二维深对流。
This paper studies the mechanisms behind the multiscale organization of tropical moist convection using a trio of cloud‐resolving atmospheric simulations performed in a periodic two‐dimensional 32,000‐km domain. A simulation with interactive surface fluxes and long‐wave radiation over a constant sea surface temperature of 300.15 K produces a planetary‐scale self‐aggregated patch of convection after 80 days of simulation. Fixing the surface fluxes and radiative cooling at a constant value suppresses this planetary‐scale organization. However, increasing the stability at the tropopause by adding stratospheric heating produces a simulation, which generates a planetary‐scale wave after just 30 days. This planetary‐scale wave modulates eastward propagating synoptic‐scale waves, which in turn modulate westward propagating mesoscale convective system. Low‐pass filters are used to diagnose the feedbacks, which produce large‐scale variance of zonal velocity, buoyancy, and humidity. The planetary‐scale buoyancy variance and zonal velocity variance are related to the available potential energy (APE) and kinetic energy (KE) budgets, respectively. In the simulation with stratospheric heating, planetary‐scale KE is created by vertical fluxes of zonal momentum, converted to APE, and then dissipated by latent heating, mixing, and other buoyancy sources. Without stratospheric heating, the KE produced by these feedbacks is strongly damped in the stratosphere. The mesoscale eddy flux convergence of zonal momentum dominates the total vertical flux feedback on the planetary‐scale KE, and its vertical structure is consistent with the westward propagating mesoscale convective systems. Overall, these results demonstrate that these eddy fluxes can organize two‐dimensional deep convection on planetary scales in the absence of other diabatic feedbacks.