Estimating Tropical Cyclone Intensity and Structure from TROPICS data

Satellite microwave (MW) imagers and sounders provide a unique ability to “see” through clouds, which is especially useful for identifying tropical cyclone (TC) structures that cannot be inferred from infrared (IR) and visible channels. MW sounders have proven to be especially useful for estimating tropical cyclone intensity and structure parameters.

The TROPICS mission is a constellation of five cubesats that carry MW sounders that possess similar sounding capabilities as the Advanced Technology Microwave Sounder (ATMS) and Advanced Microwave Sounding Unit (AMSU). The five TROPICS satellites in carefully designed orbits provide the ability to view the same TC from multiple viewing angles and high spatial resolution with a median revisit time around one hour, which is adding a significant amount of MW overpasses over TCs. For comparison, a single sun-synchronous satellite provides 0 – 2 overpasses per day for a single TC. The TROPICS sounder uses 118-GHz temperature channels that have a horizontal resolution of 24 km at nadir, which is superior to the 32 km resolution of 55-GHz ATMS temperature channels, the highest operationally available resolution, and allows for better sampling of the TC warm core. The improved horizontal resolution could be, however, partially offset by more significant scattering impact for the 118-GHz channels.

This presentation will discuss estimating TC intensity and structure from TROPICS data, as well as the comparison of TROPICS and ATMS temperature and moisture retrievals. We use the CIRA Hurricane Intensity and Structure Algorithm (HISA) to generate global objective and Dvorak-independent estimates of TC intensity and wind radii, as well as 2D TC-centric winds at multiple pressure levels. HISA is running operationally at NESDIS and produces TC intensity and structure estimates from temperature profiles retrieved with Microwave Integrated Retrieval System (MiRS) from AMSU on-board NOAA-19 and MetOp-B, and ATMS on Suomi National Polar-orbiting Partnership (SNPP) satellite. TROPICS HISA uses as input two versions of temperature retrievals: a) the TROPICS version of the operational NOAA MiRS and b) TROPICS machine learning temperature retrievals. Preliminary results will be discussed together with the possible implications for the operational use of TROPICS HISA estimates.

Disclaimer: The scientific results and conclusions, as well as any views or opinions expressed herein, are those of the author(s) and do not necessarily reflect those of NOAA or the Department of Commerce.