New satellite constellations to provide high-resolution atmospheric observations from microwave (MW) sounders operating in low-Earth orbit are now coming online and are providing operationally useful data. The first of these missions, the NASA Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) Earth Venture (EVI-3) mission, was successfully launched into orbit on May 7 and 25, 2023 (Eastern Daylight Time, two CubeSats in each of the two launches). TROPICS is now providing nearly all-weather observations of 3-D 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 (TCs). TROPICS is providing rapid-refresh MW measurements (median refresh rate of better than 60 min early in the mission with four functional CubeSats, and now approximately 70–90 min with three functional CubeSats) over the tropics that can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm lifecycle. Hundreds of high-resolution images of TCs have been captured thus far by the TROPICS mission, revealing the detailed structure of the eyewall and surrounding rain bands. The new 205-GHz channel in particular (together with a traditional channel near 92 GHz) is providing new information on the inner storm structure, and, coupled with the relatively frequent revisit and low downlink latency, is already informing TC analysis at operational centers. Here, we present an overview of the TROPICS mission after two years of successful science operations with a focus on the suite of geophysical (Level 2) products (atmospheric vertical temperature and moisture profiles, instantaneous surface rain rate, and TC intensity) and the science investigations that have been enabled by these new measurements.

Instruments on board Joint Polar Satellite System (JPSS) satellites (and other polar orbiters) provide unique operational capabilities for tropical cyclones to United States National Weather Service (NWS) forecasters throughout the Pacific basin. Data from these satellites are also used as input to forecast models that are used globally for tropical cyclone guidance. Specific products include visible imagery at night (from the Visible-Infrared Imaging Radiometer Suite -- VIIRS -- Day Night Band (DNB) that flies on the Suomi-NPP and NOAA-20 satellites), information in the microwave part of the electromagnetic spectrum as sensed by the Advanced Technology Microwave Sounder (ATMS) on Suomi-NPP and NOAA-20 and the Advanced Microwave Sounding Unit (AMSU) and Microwave Humidity Sounder (MHS) instruments on NOAA-19 (and also on EUMETSAT's MetOp series of satellites). JPSS data from ATMS and from the Cross-track Infrared Sounder (CrIS, also on board Suomi-NPP and NOAA-20) instruments are used to create vertical profiles of temperature in moisture via HEAP (Hyper-spectral Enterprise Algorithm Package; formerly NOAA-Unique Combined Atmospheric Processing System -- NUCAPS). These data sources afford a forecaster with important analysis techniques for center-fixing a tropical cyclone (TC), estimating the size of the eye (a metric that influences peak speeds) and for assessing the environment in and around the storm.