A revised ocean glider concept to realize Stommel's vision and supplement Argo floats

This paper revisits Stommel's vision for a global glider network and the Argo design specification. A concept of floats with wings, so-called slow underwater gliders, is explored. An analysis of the energy or power consumption shows that, by operating gliders with half the vehicle volume at half the speed compared to present gliders, the energy requirements for long-duration missions can be met with available battery capacities. Simulation experiments of slow gliders are conducted using the horizontal current fields from an eddy-permitting ocean reanalysis product. By employing a semi-Lagrangian, streamwise navigation whereby the glider steers at right angles to ocean currents, we show that the concept is feasible. The simulated glider tracks demonstrate the potential for efficient coverage of key oceanographic features and variability.publishedVersio

The Lofoten Basin Eddy: three years of evolution as observed by Seagliders

The Lofoten Basin in the Norwegian Sea is an area where the warm Atlantic Water is subject to the greatest heat losses anywhere in the Nordic Seas. A long-lived, deep, anticyclonic eddy is located in the central part of the basin (the Lofoten Basin Eddy, LBE). Here we use observations from Seagliders, collected between July 2012 and July 2015, to describe LBE in unprecedented detail. The missions were designed to sample LBE repeatedly, allowing for multiple realizations of radial sections across the eddy. LBE has a mean radius of 1864 km and propagates cyclonically with a mean speed of approximately 3–4 cm s21. The anticyclonic azimuthal peak velocity varies between 0.5 and 0.7 m s21, located between 700 and 900 m depth. The average contribution of geostrophy in the cyclogeostrophic balance is 44%. The relative vorticity of the core is close to the local Coriolis parameter. The evolution of core water properties shows substantial interannual variability, influenced by surface buoyancy flux and advection of anomalous low-salinity nearsurface waters that may affect the vertical extent of winter convection. A comparison of the eddy properties to those inferred from automated tracking of satellite altimeter observations shows that the location of eddy center is successfully detected to within one half eddy radius, but vorticity is underestimated and the radius overestimated, each approximately by a factor of 2, because of excessive smoothing relative to the small eddy radius.publishedVersio

Forsøk med drone til miljøovervaking i innsjø

I oktober 2013 vart det gjort forsøk med bruk av ein autonom farkost, glider, for miljøovervaking i innsjøen Hornindalsvatnet i Nordfjord. Slik farkost kan gjentekne gonger dykke til store djup og returnere til overflata og sende måledata til land. Kommunikasjon med glideren via satellitt fungerte bra, trass i høge fjell rundt vatnet. Glideren lot seg manøvrere til å dykke til berre nokre meter frå botnen før den snudde automatisk. Den innebygde funksjonen med å avbryte dykket og gå opp viss den kom nær botnen, fungerte også godt. .

Monitoring a lake by an underwater drone (glider)

I oktober 2013 vart det gjort forsøk med bruk av ein autonom farkost, glider, for miljøovervaking i innsjøen Hornindalsvatnet i Nordfjord. Slik farkost kan gjentekne gonger dykke til store djup og returnere til overflata og sende måledata til land. Kommunikasjon med glideren via satellitt fungerte bra, trass i høge fjell rundt vatnet. Glideren lot seg manøvrere til å dykke til berre nokre meter frå botnen før den snudde automatisk. Den innebygde funksjonen med å avbryte dykket og gå opp viss den kom nær botnen, fungerte også godt. ..The present report presents results from testing of an undulating underwater vehicle for environmental monitoring in a deep lake in Norway, Lake Hornindalsvatn, in October, 2013. A Slocum glider was used for the purpose. Some traditional measuring devices like lowered CTDs were applied as well, to collect data for comparisons...Vegdirektoratet/StatensVegvesenFylkesmannen i Sogn og FjordaneMiljødirektorate

A revised ocean glider concept to realize Stommel's vision and supplement Argo floats

This paper revisits Stommel's vision for a global glider network and the Argo design specification. A concept of floats with wings, so-called slow underwater gliders, is explored. An analysis of the energy or power consumption shows that, by operating gliders with half the vehicle volume at half the speed compared to present gliders, the energy requirements for long-duration missions can be met with available battery capacities. Simulation experiments of slow gliders are conducted using the horizontal current fields from an eddy-permitting ocean reanalysis product. By employing a semi-Lagrangian, streamwise navigation whereby the glider steers at right angles to ocean currents, we show that the concept is feasible. The simulated glider tracks demonstrate the potential for efficient coverage of key oceanographic features and variability

A revised ocean glider concept to realize Stommel's vision and supplement Argo floats

This paper revisits Stommel's vision for a global glider network and the Argo design specification. A concept of floats with wings, so-called slow underwater gliders, is explored. An analysis of the energy or power consumption shows that, by operating gliders with half the vehicle volume at half the speed compared to present gliders, the energy requirements for long-duration missions can be met with available battery capacities. Simulation experiments of slow gliders are conducted using the horizontal current fields from an eddy-permitting ocean reanalysis product. By employing a semi-Lagrangian, streamwise navigation whereby the glider steers at right angles to ocean currents, we show that the concept is feasible. The simulated glider tracks demonstrate the potential for efficient coverage of key oceanographic features and variability

The Lofoten Basin Eddy: three years of evolution as observed by Seagliders

The Lofoten Basin in the Norwegian Sea is an area where the warm Atlantic Water is subject to the greatest heat losses anywhere in the Nordic Seas. A long-lived, deep, anticyclonic eddy is located in the central part of the basin (the Lofoten Basin Eddy, LBE). Here we use observations from Seagliders, collected between July 2012 and July 2015, to describe LBE in unprecedented detail. The missions were designed to sample LBE repeatedly, allowing for multiple realizations of radial sections across the eddy. LBE has a mean radius of 1864 km and propagates cyclonically with a mean speed of approximately 3–4 cm s21. The anticyclonic azimuthal peak velocity varies between 0.5 and 0.7 m s21, located between 700 and 900 m depth. The average contribution of geostrophy in the cyclogeostrophic balance is 44%. The relative vorticity of the core is close to the local Coriolis parameter. The evolution of core water properties shows substantial interannual variability, influenced by surface buoyancy flux and advection of anomalous low-salinity nearsurface waters that may affect the vertical extent of winter convection. A comparison of the eddy properties to those inferred from automated tracking of satellite altimeter observations shows that the location of eddy center is successfully detected to within one half eddy radius, but vorticity is underestimated and the radius overestimated, each approximately by a factor of 2, because of excessive smoothing relative to the small eddy radius

The Iceland Greenland seas project

The Iceland Greenland Seas Project (IGP) is a coordinated atmosphere–ocean research program investigating climate processes in the source region of the densest waters of the Atlantic meridional overturning circulation. During February and March 2018, a field campaign was executed over the Iceland and southern Greenland Seas that utilized a range of observing platforms to investigate critical processes in the region, including a research vessel, a research aircraft, moorings, sea gliders, floats, and a meteorological buoy. A remarkable feature of the field campaign was the highly coordinated deployment of the observing platforms, whereby the research vessel and aircraft tracks were planned in concert to allow simultaneous sampling of the atmosphere, the ocean, and their interactions. This joint planning was supported by tailor-made convection-permitting weather forecasts and novel diagnostics from an ensemble prediction system. The scientific aims of the IGP are to characterize the atmospheric forcing and the ocean response of coupled processes; in particular, cold-air outbreaks in the vicinity of the marginal ice zone and their triggering of oceanic heat loss, and the role of freshwater in the generation of dense water masses. The campaign observed the life cycle of a long-lasting cold-air outbreak over the Iceland Sea and the development of a cold-air outbreak over the Greenland Sea. Repeated profiling revealed the immediate impact on the ocean, while a comprehensive hydrographic survey provided a rare picture of these subpolar seas in winter. A joint atmosphere–ocean approach is also being used in the analysis phase, with coupled observational analysis and coordinated numerical modeling activities underway