Four idealized, high-resolution (500 m horizontal grid spacing), numerical simulations are used to investigate the evolution of convective structures during tropical cyclogenesis. The simulations all begin with a weak initial axisymmetric cloud-free vortex in a quiescent environment, but differ in the moisture level of the initial sounding and whether or not ice microphysical processes are considered. Irrespective of experimental setup, there is only a short period where shallow or congestus clouds dominate. The shallow cloud phase is slightly extended with the drier initial environmental sounding. The composite structure of the convective elements sampled changes markedly throughout the genesis period. For much of the genesis phase, vertical profiles of the mean convective cell show significant amounts of anticyclonic vorticity produced in cells in the inner core. Towards the end of the genesis phase, there is a large increase in the production of cyclonic vertical vorticity in inner-core convection, and cyclonic vorticity becomes dominant at low-mid levels. The evolution from roughly equal strength vertical profiles of cyclonic/anticyclonic vorticity at low-mid levels to profiles where cyclonic vorticity dominates occurs at relatively low system wind speeds (V_max less than 10 m·s⁻¹). This finding indicates a change in the structure of vortical convection prior to rapid intensification. In outer-core convection, there are roughly equal strength vertical vorticity dipoles produced throughout the genesis period.

中文翻译：

---

热带气旋形成过程中对流特征的演变

四个理想化的高分辨率（500 m 水平网格间距）数值模拟用于研究热带气旋形成过程中对流结构的演变。模拟都从静止环境中的弱初始轴对称无云涡旋开始，但在初始探测的水分含量以及是否考虑冰微物理过程方面有所不同。无论实验设置如何，浅云或浓云占主导地位的时间都很短。浅云阶段随着较干燥的初始环境探测略有延长。在整个成因时期，采样的对流元素的复合结构发生了显着变化。在创世阶段的大部分时间里，平均对流单元的垂直剖面显示在内核的单元中产生了大量的反气旋涡度。到成因末期，内核对流中气旋垂直涡量大量增加，中低层气旋涡量占主导地位。从中低层气旋/反气旋涡度的强度大致相等的垂直剖面到气旋涡度占主导地位的剖面的演变发生在相对较低的系统风速下（V _max小于 10 m·s ^-1 )。这一发现表明涡流对流结构在快速增强之前发生了变化。在外核对流中，在整个成因时期产生了大致相等强度的垂直涡度偶极子。