Autonomous Underwater Glider Observations in Category 5 Hurricane Beryl

Tropical cyclones remain the costliest and deadliest weather and climate disasters globally, with impacts to coastal communities expected to increase. Over the past decade autonomous platforms have emerged as a critical component of tropical cyclone observing systems to support operational Earth system modeling and forecasting. Since 2018 autonomous underwater gliders have carried out targeted deployments as part of the NOAA Hurricane Glider Program and Coordinated Hurricane Atmosphere Ocean Sampling (CHAOS) project. The glider operator community has supported near real-time transmission and submission of all glider data to the Global Telecommunication System (GTS) for assimilation into forecast systems, regardless of science mission.

In June - July of 2024 glider RU29 captured data in advance of, throughout, and following the passage of Category 5 Hurricane Beryl in the central Caribbean Sea. It became the furthest east formation of an Atlantic hurricane in the month of June. Hurricane Beryl underwent two periods of rapid intensification while making it the first June Cat 4 storm on record, devastating the windward islands. As Beryl moved into the central Caribbean it rapidly intensified a third time and became the earliest Cat 5 storm on record. Glider RU29, equipped with a CTD, current profiler, and oxygen optode was rapidly re-positioned on the N-S track it had been sampling between Curaçao and the Dominican Republic to intersect the storm’s eye-center. RU29 started a station-keeping 24 hours in advance of Beryl’s passage with programmed 500 m dives to enable the collection of hourly profiles of temperature, salinity, velocity and oxygen. The eye of Beryl passed within 17 n mi of RU29 on 07/02 at 15:32z with maximum sustained winds of 139 knots, and a radius of maximum winds of 10 n mi. To our knowledge this is the closest approach of a Cat 5 tropical cyclone to an autonomous platform. Ongoing NOAA P3 Hurricane Hunters and saildrone missions were tasked toward the glider location, with a dropsonde targeted to the glider location on 07/02. In this presentation we will detail the glider mission, innovative piloting behaviors, operational data collection and usage, as well as preliminary analyses of the proximate upper ocean evolution during the storm event and advances through multiple collocations.