Argos DCS System Use Agreement of the Month
– February 2015
NOAA – Atlantic Oceanographic & Meteorological Laboratory
Sustained Ocean Observations for Atlantic Tropical Cyclone Intensity
This is a multi-institutional effort that brings together the research & operational components within NOAA & the University community to implement & carry out sustained & targeted ocean observations from Sea-gliders in the Caribbean Sea & southwestern tropical North Atlantic Ocean.
The upper ocean thermal structure in this region has been linked to rapid intensification of tropical cyclones and to the seasonal Atlantic hurricane activity. However, there are only a few (<300) upper ocean thermal observations carried out per year in this region, & sustained ocean observations are currently not in place or planned. In addition, for the first time, current velocity profiles will be obtained from the Sea-gliders during the second year of the work to assist hurricane forecast models to reproduce the key ocean dynamic processes associated with tropical storm-induced cooling of the ocean surface.
The main objectives of the proposed work are to implement upper ocean observations from Sea-gliders, to evaluate their impact on & to improve: (1) hurricane intensity forecasts, and (2) hurricane seasonal forecasts; using a combination of these new sustained observations, targeted observations, data analysis & current NOAA operational forecast models. The combined expertise of the investigators involved in this project in carrying out observations, data processing, data distribution, data analysis & numerical modeling, will be reflected in the implementation & positive outcomes of the proposed work.
This work will implement a pilot array of two Sea-gliders to carry out sustained & targeted upper-ocean profiling of temperature (T), salinity (S) & current velocities (u, v) in areas of the Caribbean Sea & North Tropical Atlantic Ocean. Underwater gliders are cost effective observational underwater vehicles used for targeted & sustained upper-ocean observations, they operate easily in open waters, even under hurricane strength winds, and can be navigated across moderately strong currents.
Underwater gliders are durable, autonomous and have a low-drag & hydrodynamic shape, use battery power to control their buoyancy to move vertically, and use their wings to guide themselves forward along a remotely programmed trajectory. When their batteries run out, the underwater gliders can be recovered & then refurbished & redeployed immediately. Their small size (~2m long) & low weight (~50 kg) allow for an easy deployment & recovery by two people from a small vessel.
Underwater gliders transit at approximately 20-25 km/day while executing 8-10 T-S profiles/day to 1,000 meters and of (u, v) to 200 m. They can navigate approximately 4,000 km & collect & transmit about 1,600 profiles during a 6-month deployment. While surfaced, they can also download any new instructions for altering the navigation route. Data will be transmitted in real-time into the Global Telecommunication System (GTS) & will be used by scientists involved in this & all other projects that utilize GTS profile data. In this work, each Sea-glider will provide data of approximately 2,700 profiles per year.
Argos tags will be used as an emergency beacon in the event of a loss of communications with a glider and for recoveries at the surface.