Observing abyssal motions by tracking Swallow floats in the SOFAR channel

Rossby, H. Thomas; Webb, Douglas C.

doi:10.1016/0011-7471(70)90027-6

Cited by 34 publications

(17 citation statements)

References 7 publications

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“…Consequently, even weak oceanic subsurface currents are captured by the floats' paths (see Gould, 2005). Float trajectories can be established by either recording satellite fixes when floats surface at pre-programmed intervals (ALACE and APEX floats, Davis et al, 1992) or via triangulation of times of arrival of coded sound signals (SOFAR floats, Rossby and Webb, 1970;RAFOS floats, Rossby et al, 1986;MARVOR floats, Ollitrault et al, 1994). Floats located by means of satellite fixes must ascend periodically to the surface to transmit their data, which is why they are frequently called pop-up floats.…”

Section: Float Datamentioning

confidence: 99%

Lagrangian circulation of Antarctic Intermediate Water in the subtropical South Atlantic

Núñez‐Riboni

Boebel

Ollitrault

et al. 2005

Deep Sea Research Part II: Topical Studies in Oceanography

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This study combines float data from different projects collected between 1991 and 2003 in the South Atlantic to describe the flow of Antarctic Intermediate Water (AAIW). Velocity space-time averages are calculated for various grid resolutions and with cells deformed to match the bathymetry, f/H or f/h (with H being the water depth and h being the thickness of the AAIW layer). When judged by the degree of alignment between respective isolines and the resulting average velocity fields, the best grid is based on a nominal cell size of 31 (latitude) by 41 (longitude) with cell shapes deformed according to f/h. Using this grid, objectively estimated mean currents (and their associated errors), as well as meridional and zonal volume transports are estimated. Results show an anticyclonic Subtropical Gyre centred near 361S and spanning from 23711S to 46711S. The South Atlantic Current meanders from 331S to 461S and shows a mean speed of 9.677.8 cm s À1 (8.573.5 Sv; 1 Sv ¼ 1 Â 10 6 m 3 s À1 ). The northern branch of the Subtropical Gyre is located between 221S and 321S and flows westward with a mean speed of 4.773.3 cm s À1 (9.373.4 Sv). Evidence of a cyclonic Tropical Gyre divided in two sub-cells is visible on the stream function. r

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Section: Float Datamentioning

confidence: 99%

Lagrangian circulation of Antarctic Intermediate Water in the subtropical South Atlantic

Núñez‐Riboni

Boebel

Ollitrault

et al. 2005

Deep Sea Research Part II: Topical Studies in Oceanography

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“…The surprising dispersion of the floats in all directions by the eddy field made it immediately apparent that ship‐based float tracking was impractical and insufficient to map out the subsurface ocean circulation over larger spatial and temporal scales. A long‐range acoustic float tracking method was developed by Rossby and Webb (), based on an early conceptual idea proposed by Stommel (), capitalizing on the ducting effect of the middepth “sound channel”.…”

Section: Introductionmentioning

confidence: 99%

Lagrangian Views of the Pathways of the Atlantic Meridional Overturning Circulation

et al. 2019

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The Lagrangian method—where current location and intensity are determined by tracking the movement of flow along its path—is the oldest technique for measuring the ocean circulation. For centuries, mariners used compilations of ship drift data to map out the location and intensity of surface currents along major shipping routes of the global ocean. In the mid‐20th century, technological advances in electronic navigation allowed oceanographers to continuously track freely drifting surface buoys throughout the ice‐free oceans and begin to construct basin‐scale, and eventually global‐scale, maps of the surface circulation. At about the same time, development of acoustic methods to track neutrally buoyant floats below the surface led to important new discoveries regarding the deep circulation. Since then, Lagrangian observing and modeling techniques have been used to explore the structure of the general circulation and its variability throughout the global ocean, but especially in the Atlantic Ocean. In this review, Lagrangian studies that focus on pathways of the upper and lower limbs of the Atlantic Meridional Overturning Circulation (AMOC), both observational and numerical, have been gathered together to illustrate aspects of the AMOC that are uniquely captured by this technique. These include the importance of horizontal recirculation gyres and interior (as opposed to boundary) pathways, the connectivity (or lack thereof) of the AMOC across latitudes, and the role of mesoscale eddies in some regions as the primary AMOC transport mechanism. There remain vast areas of the deep ocean where there are no direct observations of the pathways of the AMOC.

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“…Although mechani-cal current meters have been used since the 1920s, their extended use by the oceanographic community started in the 1960s thanks to improved design, accuracy and reliability of rotor-type current meters and the commercialization of modern acoustic Doppler current meters (Emery and Thomson, 2001). Simultaneously, attempts to infer deep ocean velocities by tracking drifting devices exploiting the sound fixing and ranging (SOFAR) channel located at around 1200 m depth (e.g., Rossby and Webb, 1970) were made. First prototypes designed independently by H. Stommel andJ.…”

Section: Introductionmentioning

confidence: 99%

Remote sensing of ocean surface currents: a review of what is being observed and what is being assimilated

Isern‐Fontanet

Ballabrera-Poy

Turiel

et al. 2017

Nonlin. Processes Geophys.

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Abstract. Ocean currents play a key role in Earth's climate -they impact almost any process taking place in the ocean and are of major importance for navigation and human activities at sea. Nevertheless, their observation and forecasting are still difficult. First, no observing system is able to provide direct measurements of global ocean currents on synoptic scales. Consequently, it has been necessary to use sea surface height and sea surface temperature measurements and refer to dynamical frameworks to derive the velocity field. Second, the assimilation of the velocity field into numerical models of ocean circulation is difficult mainly due to lack of data. Recent experiments that assimilate coastal-based radar data have shown that ocean currents will contribute to increasing the forecast skill of surface currents, but require application in multidata assimilation approaches to better identify the thermohaline structure of the ocean. In this paper we review the current knowledge in these fields and provide a global and systematic view of the technologies to retrieve ocean velocities in the upper ocean and the available approaches to assimilate this information into ocean models.

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Observing abyssal motions by tracking Swallow floats in the SOFAR channel

Cited by 34 publications

References 7 publications

Lagrangian circulation of Antarctic Intermediate Water in the subtropical South Atlantic

Lagrangian circulation of Antarctic Intermediate Water in the subtropical South Atlantic

Lagrangian Views of the Pathways of the Atlantic Meridional Overturning Circulation

Remote sensing of ocean surface currents: a review of what is being observed and what is being assimilated

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