An Examination of Salinity Effect on Hurricane Sally (2020)

On September the 15 ^th of 2020, Hurricane Sally traveled within 35 km from the location of NOAA NDBC Sea-glider (SG) 601 situated south of De Soto canyon. In this study, upper ocean observations from SG601 were compared to Hybrid Coordinated Ocean Model (HYCOM) and Navy Coastal Ocean Model for American Seas (NCOM-AmSeas or NCOM), coupled atmospheric-ocean models mainly used in hurricane science. Results from this study show that water temperatures, from the HYCOM simulations, were >29°C in the upper 30m and differ from SG observations by a 1°C. On HYCOM modelled upper ocean salinity, the differences (2-3PSU) are noticeable on two days (09/15 and 09/16). NCOM simulations, on the other hand, show a difference of 0.5-1°C (1.5-2PSU) in upper ~30 m water temperatures (salinity) of 09/15. Furthermore, when a 1D PWP model was initialized with a temperature and salinity profile with a barrier layer (barrier layer removed) to evaluate the influence of barrier layer on Hurricane Sally (HS), a 0.1-0.15°C (0.15°C-0.20°C) cooling of the mixed layer was noticed on 09/15.