CIRA's Hurricane Intensity and Structure Algorithm (HISA) was first developed in 2004 using input from the statistical temperature retrievals from the Advanced Microwave Sounding Units (AMSU) on-board NOAA-15 and -16. Several upgrades have been made to HISA since 2004. Currently, operational versions of HISA are using as input both statistical and Microwave Integrated Retrieval System (MiRS) temperature and cloud liquid water (CLW) retrievals from microwave sounders on-board seven polar-orbiting satellites, including NOAA-15, -16, -18, -19, MetOp-A and -B, and Suomi National Polar Orbiting Partnership (S-NPP), providing up to 14 intensity estimates per storm per day. HISA is also being adapted to work with Joint Polar Satellite System-1 (JPSS-1) Advanced Technology Microwave Sounder (ATMS)-MiRS retrievals. In addition to maximum sustained winds (MSW), minimum sea-level pressure (MSLP), and estimates of 34-, 50-, and 64- kt wind radii that are available to operational forecasters at the National Hurricane Center (NHC), Central Pacific Hurricane Center (CPHC), and Joint Typhoon Warning Center (JTWC) via Automated Tropical Cyclone Forecasting System (ATCF) f-decks, HISA is providing azimuthally averaged gradient winds and 2-D balanced winds at standard pressure levels that are available in NetCDF format. Recently, work has begun on adapting HISA to use as input data obtained from Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS). TROPICS is currently planned to include a constellation of six smallsats, all of which will be carrying ATMS-like instruments. Unlike ATMS that has 22 temperature and moisture channels ranging from 23 GHz to 191 GHz, TROPICS Radiometers (TR) only have 12 channels, ranging from 91 GHz to 205 GHz. The TROPICS version of HISA will be using TR radiances processed with a modified version of MiRS. The discussion of differences in implementing HISA on TROPICS vs ATMS, as well as recent HISA modifications that include use of moisture retrievals will be presented, together with some preliminary results.
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