Wave Glider Observations in the Southern Ocean

UW team sending autonomous surfboard to explore Antarctic waters

UW News, Hannah Hickey

The research project will use the Wave Glider to investigate the summer conditions near Palmer Station on the Antarctic Peninsula, to better understand how the warming ocean interacts with ice shelves that protrude from the shore. It will then head across Drake Passage, braving some of the stormiest seas on the planet.

23 Oct 2019

Motivation		Plan
Southern Ocean climate change is at the heart of the ocean's response to anthropogenic forcing. Variations in South Polar atmospheric circulation patterns, fluctuations in the strength and position of the Antarctic Circumpolar Current, and the intertwining intermediate deep water cells of the oceanic meridional overturning circulation have important impacts on the rate of ocean carbon sequestration, biological productivity, and the transport of heat to the melting continental ice shelves. The connections among these processes are the turbulent fluxes of heat, momentum, and gases through the air–sea interface, all of which depend on the interplay of winds, surface waves, and ocean currents. Persistent measurements of these quantities, however, are difficult to come by in the Southern Ocean.		We are using a Wave Glider (Liquid Robotics, Inc.), to which we've added a new set of capabilities including a profiling CTD winch, and high-frequency acoustic Doppler turbulence and chlorophyll fluorescence sensors. This autonomous surface vehicle will conduct a summer-season experiment to investigate ocean–shelf exchange on the West Antarctic Peninsula and frontal air–sea interaction over both the continental shelf and open ocean. Mobile autonomous surface platforms such as the Wave Glider offer a cost-effective alternative to ship surveys and can greatly extend our database of direct measurements of Southern Ocean air–sea processes.

Media — 2017 Deployment
Successful Wave Glider Mission in the Southern Ocean.		Using an autonomous platform allowed us to have persistence in the region, as well as track or target the fronts and gradients that make the place so interesting.

November 2019 – February 2020
Wave Glider operations in the Southern Ocean have two key constraints: deployment or recovery in the rough seas of the Drake Passage is to be avoided, and solar charging limits Wave Glider operations at these latitudes to the months of October–February. Wave Glider will be deployed from the ARSV Laurence M. Gould near Palmer Station in Nov–Dec 2019 and will participate in coordinated operations with the Rutgers University Slocum glider near the shelf-break and across the region making up the Palmer Long-Term Ecological Research (LTER) site. In Jan 2020 Wave Glider will head north in the Drake Passage to survey Antarctic Circumpolar Current fronts. And in Feb 2020 Wave Glider will travel northward, complete a crossing of the Drake Passage, and be recovered in the Argentine EEZ.

Experimental plan overview: West Antarctic Peninsula and open-ocean fronts surveys. Boxes indicate focus regions expanded in figures below. Red contours show an AVISO dynamic topography (5-cm interval) snapshot.


Schematic patterns of West Antarctic Peninsula Shelf survey. Red contours show a snapshot of AVISO dynamic topography (1-cm intervals) and red arrows illustrate the Southern Antarctic Circumpolar Current pathway and shelf intrusion.		Schematic patterns of open-ocean fronts surveys. Black contours show a snapshot of AVISO dynamic topography (5-cm intervals).

Measurements of directional wave spectra and wind stress from a Wave Glider autonomous surface vehicle

Thomson, J., J.B. Girton, R. Jha, and A. Trapani "Measurements of directional wave spectra and wind stress from a Wave Glider autonomous surface vehicle," J. Atmos. Ocean. Technol., 35, 347-363, doi:10.1175/JTECH-D-17-0091.1, 2018.

More Info

1 Feb 2018

Methods for measuring waves and winds from a Wave Glider Autonomous Surface Vehicle (ASV) are described and evaluated. The wave method utilizes the frequency spectra of orbital velocities measured by GPS, and the wind stress method utilizes the frequency spectra of turbulent wind fluctuations measured by ultrasonic anemometer. Both methods evaluate contaminations from vehicle motion. The methods were evaluated with 68 days of data over a full range of open ocean conditions, in which wave heights varied from 1 to 8 m and wind speeds varied from 1 to 17 m/s. Reference data were collected using additional sensors onboard the vehicle. For the waves method, several additional datasets are included which use independently moored Datawell waverider buoys as reference data. Bulk wave parameters are determined waverider buoys as reference data. Bulk wave parameters are determined within 5% error, with biases of less than 5%. Wind stress is determined within 4% error, with 1% bias. Wave directional spectra also compare well, although the Wave Glider results have more spread at low frequencies.

Sustained measurements of Southern Ocean air–sea coupling from a Wave Glider autonomous surface vehicle

Thomson, J., and J. Girton, "Sustained measurements of Southern Ocean air–sea coupling from a Wave Glider autonomous surface vehicle," Oceanography, 30, 104-109, doi:10.5670/oceanog.2017.228, 2017.

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1 Jun 2017

The four-month mission of a Wave Glider in the Southern Ocean has demonstrated the capability for an autonomous surface vehicle to make sustained measurements of air-sea interactions in remote regions. Several new sensor payloads were integrated for this mission, including a three-axis sonic anemometer for turbulent wind stress estimation and a high-resolution atmospheric pressure gage. The mission focused on Drake Passage, where strong gradients are common along the Antarctic Circumpolar Current (ACC) fronts. Using satellite data products, pilots ashore were able to remotely navigate the Wave Glider across the ACC Polar Front and measure changes in air-sea coupling. The resulting data set combines the persistence of a mooring with the adaptability of a ship-based survey.