TROPICS01 Pathfinder L2B Tropical Cyclone Intensity Estimate (TCIE) Algorithm V1.0

The "Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats" (TROPICS) mission has a goal of providing nearly all-weather observations of three-dimensional temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high-value science investigations of tropical cyclones. The mission comprises a constellation of five identical Space Vehicles (SVs) conforming to the 3U form factor and hosting a passive microwave spectrometer payload.

Each SV hosts an identical high-performance spectrometer named the TROPICS Millimeter-wave Sounder (TMS) that will provide temperature profiles using seven channels near the 118.75-GHz oxygen absorption line, water vapor profiles using three channels near the 183-GHz water vapor absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher resolution water vapor channels), and a single channel near 205 GHz that is more sensitive to cloud-sized ice particles.

The TROPICS Tropical Cyclone Intensity Estimate algorithm (TCIE), developed at the University of Wisconsin/CIMSS that uses native microwave brightness temperatures, estimates two primary TC variables: Minimum Sea Level Pressure (MSLP) and Maximum Sustained Winds (MSW). The TROPICS TCIE uses the brightness temperature perturbation of two temperature sounding channels (Ch. 6 and Ch. 7) and one channel from the moisture sounding channel (Ch. 1) along with ancillary information from the TC working best track file and the CIMSS ARCHER algorithm (eye size information) to estimate the TC intensity. This validated TCIE data release starts in June 2023 for the constellation CubeSats, and August 2021 for the TROPICS-01/Pathfinder.

“小卫星星座降水结构与风暴强度时间分辨率观测”（Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats，简称TROPICS）任务的目标是以高时间分辨率获取近乎全天气条件下的三维温湿度、云冰与降水水平结构观测数据，用于开展热带气旋的高价值科学研究。该任务由5颗完全一致的航天器（Space Vehicles，简称SV）组成，均遵循3U构型，并搭载无源微波光谱仪载荷。

每颗航天器均搭载同款高性能光谱仪——TROPICS毫米波测深仪（TROPICS Millimeter-wave Sounder，简称TMS），其可通过118.75GHz氧吸收线附近的7个通道获取温度廓线，通过183GHz水汽吸收线附近的3个通道获取水汽廓线；通过90GHz附近的单通道成像（结合更高分辨率的水汽通道）开展降水观测，并通过205GHz附近的单通道对云尺度冰粒子实现更高灵敏度探测。

威斯康星大学/CIMSS开发的TROPICS热带气旋强度估计算法（TROPICS Tropical Cyclone Intensity Estimate，简称TCIE），依托原生微波亮温数据，可估算热带气旋（Tropical Cyclone，简称TC）的两项核心变量：最低海平面气压（Minimum Sea Level Pressure，简称MSLP）与最大持续风速（Maximum Sustained Winds，简称MSW）。该TROPICS TCIE算法利用2个温度探测通道（第6通道与第7通道）、1个水汽探测通道（第1通道）的亮温扰动值，结合热带气旋最佳路径文件的辅助信息以及CIMSS ARCHER算法提供的眼区尺寸信息，完成热带气旋强度估算。此经过验证的TCIE数据发布起始时间为：2023年6月（对应本星座立方体卫星CubeSat），以及2021年8月（对应TROPICS-01/路径探测器）。