NOAA/AOML-CARICOOS Underwater Glider Operations in Support of Tropical Cyclone Intensification Studies

Every Atlantic Hurricane season since July 2014, an array of underwater gliders is deployed off Puerto Rico by NOAA's Atlantic Oceanographic & Meteorological Laboratory (AOML) and the Caribbean Coastal Ocean Observing System (CARICOOS) as part of a multi-institutional effort. The goal of this work is to enhance our knowledge on the role of the ocean on the intensification of tropical cyclones (TC) in the Atlantic Ocean. Sustained and targeted upper-ocean profile observations from underwater gliders are carried out to assess the upper ocean response to hurricane force winds and to evaluate the impact of these observations on tropical cyclone intensity forecasts. Glider observations provide valuable data on the ocean's thermal and haline structure prior to a storm's arrival, during the storm, and after the storm has passed. Initial findings from this study have shown that assimilation of glider data into coupled tropical cyclone forecast models, specifically the Hurricane Weather Research and Forecasting (HWRF) Model-Hybrid Coordinate Ocean Model (HYCOM), significantly improved the initial upper ocean thermal and haline conditions near the glider locations and beyond. Another finding from these studies was that salinity plays an important role in suppressing the hurricane induced upper ocean cooling by creating a nearsurface barrier layer, causing temperature changes to be less than expected, which helps sustain the TC intensification.