A Global Tropical Cyclone Eye Climatology from HURSAT B1

Tropical cyclones, when most intense, often produce a cloud free center with calm winds, called the eye. Using Hurricane Satellite (HURSAT) B1 infrared (IR) imagery data and the Automated Rotational Center Hurricane Eye Retrieval (ARCHER) algorithm, the occurrence of tropical cyclone eyes from 1982-2015 are analyzed. The HURSAT B1 data provides regular (3-hourly) observations of storms, providing regular observations of tropical cyclones and their eyes. The result is a 34-year climatology of eyes. Eyes are identified in about 13% of all IR images of tropical cyclones and slightly more than half of all storms during that time period produced an eye. Those that produce an eye have (on average) 30 hours of eye scenes. However, some storms have more: Hurricane Ioke (1992) had the most with 98 eye images (which is 12 complete days with an eye). The median wind speed of a system with an eye is 97 knots (compared to 35 knots for those without an eye). Eyes are much more frequent in the Northern Hemisphere (particularly in the Western Pacific) but eyes are larger in the Southern Hemisphere. The occurrence of an eye can provide an objective measure of tropical cyclone activity since it is unrelated to human designations or practices. This climatology could allow analysis of further relationships of storm morphology, structure, and intensity.