The Rapid Intensification of Hurricane Michael (2018): Storm Structure and the Relationship to Environmental and Air–Sea Interactions
The Rapid Intensification of Hurricane Michael (2018): Storm Structure and the Relationship to Environmental and Air–Sea Interactions
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DOI：
10.1175/mwr-d-20-0145.1
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发表时间：
2020-10
影响因子：
3.2
通讯作者：
Joshua B. Wadler;Jun A. Zhang;R. Rogers;B. Jaimes;L. Shay
中科院分区：
文献类型：
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作者：
Joshua B. Wadler;Jun A. Zhang;R. Rogers;B. Jaimes;L. Shay
使用NOAA WP-3D和G-IV飞机任务获得的耦合大气-海洋数据集探索飓风迈克尔（2018）快速增强期间多尺度结构的时空变化。在迈克尔的早期生命周期中，海洋结构的重要性被研究，以探索风暴如何在经历中度垂直切变的情况下增强。迈克尔保持了相当对称的降水分布，并阻止了干燥环境空气横向混合到高空环流中。风暴还与海洋涡流场相互作用，导致风暴间的海表温度梯度约为2.5°C。这导致了最高的焓通量发生在切变的左边，有利于维持上升气流进入上切变象限，并从低熵的下降气流中快速恢复。在生命周期的后期，迈克尔与更均匀和更高的SST相互作用，SST大于28°C，而垂直切变则使迈克尔的次级环流和熵分布不对称。中层（约4-8公里）的外流向下切变，这是切变飓风的特征，将高熵空气从眼壁区向外输送。这种外流产生了一个帽，减少了边界层顶部的夹带，保护它免受干燥的对流层中层空气的大半径影响（即，>100公里），并允许从海气焓通量的快速能量增加。上升切变，低层（~0.5-2公里）外流向外输送高熵空气，这有助于从低熵下沉气流中恢复边界层。这项研究强调了同时测量大气和海洋参数以了解快速增强期间热带气旋结构的重要性。
The spatial and temporal variation in multiscale structures during the rapid intensification of Hurricane Michael (2018) are explored using a coupled atmospheric–oceanic dataset obtained from NOAA WP-3D and G-IV aircraft missions. During Michael’s early life cycle, the importance of ocean structure is studied to explore how the storm intensified despite experiencing moderate vertical shear. Michael maintained a fairly symmetric precipitation distribution and resisted lateral mixing of dry environmental air into the circulation upshear. The storm also interacted with an oceanic eddy field leading to cross-storm sea surface temperature (SST) gradients of ~2.5°C. This led to the highest enthalpy fluxes occurring left of shear, favoring the sustainment of updrafts into the upshear quadrants and a quick recovery from low-entropy downdraft air. Later in the life cycle, Michael interacted with more uniform and higher SSTs that were greater than 28°C, while vertical shear imposed asymmetries in Michael’s secondary circulation and distribution of entropy. Midlevel (~4–8 km) outflow downshear, a feature characteristic of hurricanes in shear, transported high-entropy air from the eyewall region outward. This outflow created a cap that reduced entrainment across the boundary layer top, protecting it from dry midtropospheric air out to large radii (i.e., >100 km), and allowing for rapid energy increases from air–sea enthalpy fluxes. Upshear, low-level (~0.5–2 km) outflow transported high-entropy air outward, which aided boundary layer recovery from low-entropy downdraft air. This study underscores the importance of simultaneously measuring atmospheric and oceanographic parameters to understand tropical cyclone structure during rapid intensification.