Observed Kinematic and Thermodynamic Structure in the Hurricane Boundary Layer during Intensity Change
Observed Kinematic and Thermodynamic Structure in the Hurricane Boundary Layer during Intensity Change
复制标题
DOI：
10.1175/mwr-d-18-0380.1
复制
发表时间：
2019-07
影响因子：
3.2
通讯作者：
Kyle Ahern;M. Bourassa;R. Hart;Jun A. Zhang;R. Rogers
中科院分区：
文献类型：
--
作者：
Kyle Ahern;M. Bourassa;R. Hart;Jun A. Zhang;R. Rogers
在增强[IN;强度趋势≥20 kt（24 h）−1，其中1 kt = 0.5144 m s−1]、减弱[WE;强度趋势<−10 kt（24 h）−1]和稳定状态[SS;剩余的]时间段使用1998年至2015年期间侦察任务的GPS落风探空仪的合成物进行分析。总共有3091个投下式探空仪在2.5公里高度以下进行了合成分析--IN期间为1086个，WE期间为1042个，SS期间为963个。在非强化飓风中，最大风速半径（RMW）外的低空切向风大于强化飓风，这意味着非强化飓风在这些半径处具有更高的惯性稳定性（I2）。各组间切向风结构（和I2）的差异也意味着次级环流的差异。IN径向流入层的厚度几乎等于或大于nonintensifying组，并且所有组都显示出RMW外部的流入最大值。非增强型飓风在眼墙区域外有更强的流入，这可能与在RMW外半径处强迫上升离开BL和增强下沉进入BL有关。非增强风暴的RMW内的等效位温（θe）和条件稳定度最高，这可能与TC强度有关。在更大半径处，WE飓风的流入层θe最低，这表明与IN和SS飓风相比，这些半径处的下沉更大或对流下降气流更多。强调了先前观测和理论研究的比较，特别是那些将BL结构与大尺度涡旋结构、对流和强度相关的研究。
The axisymmetric structure of the inner-core hurricane boundary layer (BL) during intensification [IN; intensity tendency ≥20 kt (24 h)−1, where 1 kt ≈ 0.5144 m s−1], weakening [WE; intensity tendency <−10 kt (24 h)−1], and steady-state [SS; the remainder] periods are analyzed using composites of GPS dropwindsondes from reconnaissance missions between 1998 and 2015. A total of 3091 dropsondes were composited for analysis below 2.5-km elevation—1086 during IN, 1042 during WE, and 963 during SS. In nonintensifying hurricanes, the low-level tangential wind is greater outside the radius of maximum wind (RMW) than for intensifying hurricanes, implying higher inertial stability (I2) at those radii for nonintensifying hurricanes. Differences in tangential wind structure (and I2) between the groups also imply differences in secondary circulation. The IN radial inflow layer is of nearly equal or greater thickness than nonintensifying groups, and all groups show an inflow maximum just outside the RMW. Nonintensifying hurricanes have stronger inflow outside the eyewall region, likely associated with frictionally forced ascent out of the BL and enhanced subsidence into the BL at radii outside the RMW. Equivalent potential temperatures (θe) and conditional stability are highest inside the RMW of nonintensifying storms, which is potentially related to TC intensity. At greater radii, inflow layer θe is lowest in WE hurricanes, suggesting greater subsidence or more convective downdrafts at those radii compared to IN and SS hurricanes. Comparisons of prior observational and theoretical studies are highlighted, especially those relating BL structure to large-scale vortex structure, convection, and intensity.