Previous numerical simulations have focused mainly on the mesoscale structure of the principal rainband in tropical cyclones with a relatively coarse model resolution. In this study, the principal rainband was simulated in a semi-idealized experiment at a horizontal grid spacing of 1/9 km and its convective-scale structure was examined by comparing the convective elements of the simulated principal rainband with previous observational studies. It is found that the convective scale structure of the simulated principal rainband is well comparable to the observation. The azimuthal variations of the convective scale structure were examined by dividing the simulated principal rainband into the upwind, middle and downwind portions. Some new features are found in the simulated principal rainband. First, the overturning updraft contains small-scale rolls aligned along the inward side of the outward-leaning reflectivity tower in the middle portion. Second, the inner-edge downdraft is combined with a branch of inflow from the upper levels in middle and downwind portions, carrying upper-level dry air to the region between the overturning updrafts and eyewall, and the intrusion of the upper-level dry air further limits the altitude of the overturning updrafts in the middle and downwind portions of the principal rainband. Third, from the middle to downwind portions, the strength of the secondary horizontal wind maximum is gradually replaced by a low-level maximum of the tangential wind collocated with the low-level downdraft.

中文翻译：

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模拟热带气旋主雨带中对流尺度结构的方位角变化

以前的数值模拟主要集中在热带气旋主雨带的中尺度结构上，模式分辨率相对较粗。本研究在水平网格间距为1/9 km的半理想化实验中模拟了主雨带，并通过将模拟主雨带的对流元素与先前的观测研究进行比较来检查其对流尺度结构。发现模拟的主雨带的对流尺度结构与观测具有较好的可比性。通过将模拟的主雨带划分为上风、中风和下风部分，研究了对流尺度结构的方位角变化。在模拟的主雨带中发现了一些新特征。第一的，倾覆的上升气流包含沿着中间部分向外倾斜的反射塔的内侧排列的小卷。其次，内缘下沉气流与中下风部分的上层进流相结合，将上层干空气带到翻转上升气流与眼墙之间的区域，并侵入上层干空气进一步限制了主雨带中部和下风部分倾覆上升气流的高度。第三，从中间到下风部分，次水平风最大强度逐渐被低层切向风与低层下降气流并置的低层最大强度所取代。内缘下沉气流在中风和下风部分与上层流入的分支相结合，将上层干空气带到翻转上升气流和眼墙之间的区域，上层干空气的侵入进一步限制了上层干空气的侵入。主雨带中部和下风部分倾覆上升气流的高度。第三，从中间到下风部分，次水平风最大强度逐渐被低层切向风与低层下降气流并置的低层最大强度所取代。内缘下沉气流在中风和下风部分与上层流入的分支相结合，将上层干空气带到翻转上升气流和眼墙之间的区域，上层干空气的侵入进一步限制了上层干空气的侵入。主雨带中部和下风部分倾覆上升气流的高度。第三，从中间到下风部分，次水平风最大强度逐渐被低层切向风与低层下降气流并置的低层最大强度所取代。上层干空气的侵入进一步限制了主雨带中下风部分倾覆上升气流的高度。第三，从中间到下风部分，次水平风最大强度逐渐被低层切向风与低层下降气流并置的低层最大强度所取代。上层干空气的侵入进一步限制了主雨带中下风部分倾覆上升气流的高度。第三，从中间到下风部分，次水平风最大强度逐渐被低层切向风与低层下降气流并置的低层最大强度所取代。