The diurnal cycle of tropical cyclones (TCs) is a daily cycle in clouds that appears in satellite images and may have implications for TC structure and intensity. The diurnal pattern can be seen in infrared (IR) satellite imagery as cyclical pulses in the cloud field that propagate radially outward from the center of nearly all Atlantic-basin TCs. These diurnal pulses, a distinguishing characteristic of the TC diurnal cycle, begin forming in the storm's inner core near sunset each day and appear as a region of cooling cloud-top temperatures. The area of cooling takes on a ring-like appearance as cloud-top warming occurs on its inside edge and the cooling moves away from the storm overnight, reaching several hundred kilometers from the circulation center by the following afternoon. The state-of-the-art TC diurnal cycle measurement has a limited ability to analyze the behavior beyond qualitative observations. We present a method for quantifying the TC diurnal cycle using one-dimensional persistent homology, a tool from Topological Data Analysis, by tracking maximum persistence and quantifying the cycle using the discrete Fourier transform. Using Geostationary Operational Environmental Satellite IR imagery data from Hurricane Felix (2007), our method is able to detect an approximate daily cycle.

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使用持久同源性来量化飓风菲利克斯的昼夜循环

热带气旋 (TC) 的昼夜循环是出现在卫星图像中的云中的每日循环，可能对 TC 的结构和强度产生影响。昼夜模式可以在红外 (IR) 卫星图像中看到，作为云场中的周期性脉冲，从几乎所有大西洋盆地 TC 的中心径向向外传播。这些昼夜脉冲是 TC 昼夜循环的一个显着特征，每天在日落附近开始在风暴的内核中形成，并表现为云顶温度变冷的区域。冷却区域呈现环形外观，因为云顶在其内侧边缘发生变暖，并且冷却在一夜之间远离风暴，到第二天下午到达距环流中心数百公里。最先进的 TC 昼夜循环测量在分析定性观察之外的行为方面的能力有限。我们提出了一种使用一维持久同源性（拓扑数据分析中的工具）量化 TC 昼夜循环的方法，通过跟踪最大持久性并使用离散傅立叶变换量化循环。使用来自飓风费利克斯 (2007) 的地球同步运行环境卫星红外图像数据，我们的方法能够检测到近似的每日周期。