The ability to forecast tropical cyclone (TC) intensity has improved modestly in recent years, partly because of an inadequate understanding of eyewall convection processes. Short-term periodic convection activities (period: 3–5 h) have been identified in a number of TCs, but the effect of these activities on the evolution of TC intensity at the hourly scale is yet to be fully investigated. Using radar observations and a high-resolution numerical simulation based on the Weather Research and Forecasting model, we analyzed the periodic cycles of eyewall convection associated with the intensification of Typhoon Hato (2017). Results indicate the presence of four short-term periodic cycles (period: 3–5 h) in the eyewall convection, which correspond to TC intensification. We further divided each cycle into three stages. The periodic evolution of convection inhibited the rapid intensification of the TC. The highest and lowest intensification rates were associated with the first and third stages according to the virtual potential temperature tendency in the eyewall region, respectively. Heating was dominated by the vertical advection associated with sensible heat and latent heat, which were controlled by the eyewall convection and structure. Of the three stages in each cycle, the vertical transport released the largest amount of latent heat in the first stage; consequently, the highest intensification rate occurred in this stage. In the second stage, heating was reduced because of decreased latent heat and increased cooling of sensible heat associated with vertical advection as the eyewall intensified. Vertical transport was the weakest in the third stage; this resulted in the smallest amount of heating, which limited the rapid intensification of the TC.

中文翻译：

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眼壁对流的周期性循环限制了台风哈托 (2017) 的快速增强

近年来，预测热带气旋 (TC) 强度的能力略有提高，部分原因是对眼壁对流过程的了解不足。在许多 TC 中已经确定了短期周期性对流活动（周期：3-5 小时），但这些活动对 TC 强度在小时尺度上的演变的影响尚未得到充分研究。我们使用雷达观测和基于天气研究与预报模型的高分辨率数值模拟，分析了与台风哈托（2017）加剧有关的眼墙对流的周期性周期。结果表明眼壁对流中存在四个短期周期循环（周期：3-5 小时），这对应于 TC 增强。我们进一步将每个周期分为三个阶段。对流的周期性演变抑制了台风的快速增强。根据眼壁区域的虚拟潜在温度趋势，最高和最低的强化率分别与第一和第三阶段相关。取暖主要是与显热和潜热相关的垂直平流，受眼壁对流和结构控制。每个循环的三个阶段中，第一阶段垂直输运释放的潜热最大；因此，最高的集约化率出现在这个阶段。在第二阶段，由于随着眼壁加强，与垂直平流相关的潜热减少和显热冷却增加，加热减少。第三阶段垂直运输最弱；