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 this diurnal cycle, begin forming in the storm’s inner core near sunset each day, appearing 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 in IR satellite imagery 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 from Hurricanes Felix and Ivan, our method is able to detect an approximate daily cycle.

热带气旋（TCs）的昼夜周期是出现在卫星图像中的云层的每日周期，可能对TC结构和强度有影响。昼夜模式在红外（IR）卫星图像中可以看作是云场中的循环脉冲，该脉冲从几乎所有大西洋盆地TC的中心径向向外传播。这些昼夜脉冲是这一昼夜周期的显着特征，每天在日落附近在风暴的内核中开始形成，表现为降温的云顶温度区域。降温区域呈环形，这是因为其内部边缘出现了云层顶变暖，并且降温在夜间远离风暴，并在第二天下午到达距循环中心几百公里的位置。红外卫星图像中最先进的TC昼夜周期测量在定性观测之外分析行为的能力有限。我们提出了一种方法，该方法使用一维持久性同源性（一种来自拓扑数据分析的工具）来量化TC日循环，方法是跟踪最大持久性并使用离散傅里叶变换来量化该周期。使用来自飓风费利克斯和伊凡的对地静止运行环境卫星红外图像，我们的方法能够检测到近似的每日周期。通过跟踪最大持久性并使用离散傅立叶变换量化周期。使用来自飓风费利克斯和伊凡的对地静止运行环境卫星红外图像，我们的方法能够检测到近似的每日周期。通过跟踪最大持久性并使用离散傅立叶变换量化周期。使用来自飓风费利克斯和伊凡的对地静止运行环境卫星红外图像，我们的方法能够检测到近似的每日周期。