Impact of Stratiform Rainband Heating on the Tropical Cyclone Wind Field in Idealized Simulations
Impact of Stratiform Rainband Heating on the Tropical Cyclone Wind Field in Idealized Simulations
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DOI：
10.1175/jas-d-18-0335.1
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发表时间：
2019-07
影响因子：
3.1
通讯作者：
Chau-Lam Yu;A. Didlake
中科院分区：
文献类型：
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作者：
Chau-Lam Yu;A. Didlake
使用理想化的模拟，我们研究了风暴尺度的风场响应的干燥，飓风般的涡旋规定的层状加热廓线，模仿热带气旋（TC）螺旋雨带。这些廓线相对于风暴中心是静止的，代表准静止雨带复合体施加的非绝热强迫。第一个配置文件是典型的层状降水与加热以上和冷却以下的熔化水平。涡旋响应包括中尺度下降入流和中层切向急流，与先前的研究一致。另一个响应是雨带加热内部径向向内螺旋形的低空上升气流。第二个配置文件是一个修改后的层状加热结构来自于观测和对角偶极子的加热和冷却。同样的特征被发现与更强的震级和更大的垂直范围。研究了强迫低层上升气流的动力学和影响。这种上升气流是由平流浮力驱动的，因为层状结构引起的低层冷池。雨带非绝热强迫的稳定性在调节维持上升气流所需的温度和压力异常方面发挥了重要作用。对湿度和微物理的模拟证实，这种低层上升气流的反应是强大的，能够引发持续的深对流，这可能会进一步影响风暴的演变，包括在次级眼壁形成中发挥潜在作用。
Using idealized simulations, we examine the storm-scale wind field response of a dry, hurricane-like vortex to prescribed stratiform heating profiles that mimic tropical cyclone (TC) spiral rainbands. These profiles were stationary with respect to the storm center to represent the diabatic forcing imposed by a quasi-stationary rainband complex. The first profile was typical of stratiform precipitation with heating above and cooling below the melting level. The vortex response included a mesoscale descending inflow and a midlevel tangential jet, consistent with previous studies. An additional response was an inward-spiraling low-level updraft radially inside the rainband heating. The second profile was a modified stratiform heating structure derived from observations and consisted of a diagonal dipole of heating and cooling. The same features were found with stronger magnitudes and larger vertical extents. The dynamics and implications of the forced low-level updraft were examined. This updraft was driven by buoyancy advection because of the stratiform-induced low-level cold pool. The stationary nature of the rainband diabatic forcing played an important role in modulating the required temperature and pressure anomalies to sustain this updraft. Simulations with moisture and full microphysics confirmed that this low-level updraft response was robust and capable of triggering sustained deep convection that could further impact the storm evolution, including having a potential role in secondary eyewall formation.