Effects of Roll Vortices on the Evolution of Hurricane Harvey during Landfall
Effects of Roll Vortices on the Evolution of Hurricane Harvey during Landfall
复制标题
滚动涡旋对飓风哈维登陆期间演变的影响
DOI：
10.1175/jas-d-20-0270.1
复制
发表时间：
2021
影响因子：
3.1
通讯作者：
Gao, Zhiqiu
中科院分区：
文献类型：
--
作者：
Li, Xin;Pu, Zhaoxia;Gao, Zhiqiu
水平边界层滚转涡是飓风边界层中常见的一系列大尺度湍流涡旋。本文采用基于天气研究与预报（WRF）模式的单向嵌套亚公里尺度大涡模拟（LES），研究了滚涡对飓风哈维登陆前后演变的影响。0000 UTC 8月25日至1800 UTC 2017年8月27日。模拟结果表明，大涡模拟中的湍流主要是由滚转涡引起的。大涡模拟中加入了滚转涡，能较好地模拟飓风风场垂直结构和降水。相比之下，中尺度模拟与YSU PBL方案高估了海洋上的飓风降水。进一步的分析表明，滚涡引入了正的垂直通量和较薄的入流层，而负通量保持最大切向风在地面上约400米。在飓风登陆期间，弱的负通量维持了LES的较高风速。在中尺度模拟中，由于YSU方案高估了低层垂直通量，导致高估了海洋上的飓风强度，加速了飓风在登陆期间的衰减。降水分析表明，涡卷的存在导致了低涡区上升气流的减弱和水汽供应的不足。在YSU方案的模拟中，强烈的上升气流加上多余的水汽最终导致海洋上空的飓风产生了不切实际的暴雨。
Horizontal boundary layer roll vortices are a series of large-scale turbulent eddies that prevail in a hurricane’s boundary layer. In this paper, a one-way nested sub-kilometer-scale large-eddy simulation (LES) based on the Weather Research and Forecasting (WRF) Model was used to examine the impact of roll vortices on the evolution of Hurricane Harvey around its landfall from 0000 UTC 25 August to 1800 UTC 27 August 2017. The simulation results imply that the turbulence in the LES can be attributed mainly to roll vortices. With the representation of roll vortices, the LES provided a better simulation of hurricane wind vertical structure and precipitation. In contrast, the mesoscale simulation with the YSU PBL scheme overestimated the precipitation for the hurricane over the ocean. Further analysis indicates that the roll vortices introduced a positive vertical flux and thinner inflow layer, whereas a negative flux maintained the maximum tangential wind at around 400 m above ground. During hurricane landfall, the weak negative flux maintained the higher wind in the LES. The overestimated low-level vertical flux in the mesoscale simulation with the YSU scheme led to overestimated hurricane intensity over the ocean and accelerated the decay of the hurricane during landfall. Rainfall analysis reveals that the roll vortices led to a weak updraft and insufficient water vapor supply in the LES. For the simulation with the YSU scheme, the strong updraft combined with surplus water vapor eventually led to unrealistic heavy rainfall for the hurricane over the ocean.