In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes
In Situ Observations of the Diurnal Variation in the Boundary Layer of Mature Hurricanes
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DOI：
10.1029/2019gl086206
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发表时间：
2020-02
影响因子：
5.2
通讯作者：
Jun A. Zhang;J. Dunion;D. Nolan
中科院分区：
文献类型：
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作者：
Jun A. Zhang;J. Dunion;D. Nolan
最近的研究表明，热带气旋（tc）的结构，特别是由卫星红外亮度、温度和降水所显示的高层云，随着日循环而波动。包括边界层在内的低层结构的日循环还没有被观测到。本研究分析了2242个成熟飓风GPS落差探空仪的数据，探讨了平均边界层结构的日变化。对夜间（当地时间0-6点）和下午（当地时间12-18点）的运动学和热力学结构进行了综合分析。综合结果表明，夜间入流更强，湿熵也比白天大。相对于当地时间，将下沉探空仪数据分组为6小时的时间窗口，可以清楚地看到边界层入流的日变化信号。日信号的振幅在半径250-500公里处最大。
Recent studies have suggested that the structure of tropical cyclones (TCs), especially the upper‐level clouds as indicated by satellite infrared brightness temperatures and precipitation, fluctuates with the diurnal cycle. The diurnal cycle of the low‐level structure, including the boundary layer, has not yet been investigated with observations. This study analyzes data from 2242 GPS dropsondes collected in mature hurricanes to investigate the diurnal variation of the mean boundary layer structure. A composite analysis is conducted to compare the kinematic and thermodynamic structure during nighttime (0–6 local time) vs in the afternoon (12–18 local time). The composites show that much stronger inflow occurs during nighttime and the moist entropy is also larger than that in the daytime. Grouping the dropsonde data into 6‐h time windows relative to the local time shows a clear diurnal signal of boundary layer inflow. The amplitude of the diurnal signal is largest at a radius of 250–500 km.