Towards Better Estimates of Tropical Cyclone Intensity and Structure Parameters from Microwave Soundings

Temperature and moisture retrievals from microwave (MW) sounders onboard JPSS and MetOp polar-orbiting satellites and smallsats such as the Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) provide information about the tropical cyclone (TC) structure that is not readily available from other sources. These data are especially important for the systems in remote locations, which comprise the majority of all global TCs. The operational MW sounders include Advanced Technology Microwave Sounder (ATMS), Advanced Microwave Sounding Unit (AMSU), and TROPICS.

CIRA developed an updated version of the ATMS/AMSU Hurricane Intensity and Structure Algorithm (HISA) that uses MW temperature retrievals to estimate maximum wind, minimum sea level pressure, and radii of 34-, 50-, and 64- kt winds. HISA intensity and structure estimates are available for global TCs, for pre-TC disturbances (invests) and all developed systems, and are independent of Dvorak intensity estimates. In addition, HISA generates gradient winds, azimuthally-averaged temperature profiles, and 2D horizontal winds at standard pressure levels. The updated ATMS/AMSU HISA is scheduled to become operational at NESDIS at the end of 2024.

The presentation will discuss verification statistics for the updated HISA and an analysis of scenarios where HISA tends to produce good and bad estimates. In addition, we will show preliminary results from running HISA using TROPICS retrievals as input, and compare statistics from ATMS/AMSU and TROPICS HISA runs. We will also discuss development of new qualitative products from temperature and moisture retrievals and from HISA outputs. Finally, we will show preliminary results on improving HISA performance for intensity and structure estimates, demonstrate how HISA output can be used to improve TC intensity forecasts using new diagnostics from the HISA output, including vortex depth and tilt, and discuss current and planned demonstrations and forecaster’s feedback.