The Iceland–Faroe Front: A Synergistic Study of Hydrography and Altimetry

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  • 1 James Rennell Centre for Ocean Circulation, Institute of Oceanographic Sciences, Deacon Laboratory, Southampton, England
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Abstract

Two triangular hydrographic surveys were conducted in the Iceland-Faroes region with sampling corresponding to the ERS-1 3-day commissioning-phase orbit. The CTD, XBT, and ADCP data show a very active frontal region changing on the order of days. Likewise, the altimetric and infrared data also show a highly variable region. The CTDIXBT data and the altimetric data are synergistically combined in an implementation of the Bernoulli inverse method to calculate velocity fields. A priori information for the inverse are the ERS-1 altimeter height differences. The method produces a velocity field much different from that using a strict reference depth of 800 m for a level of no motion. Velocities of 15–20 cm s−1 flow eastward along the shelf at a depth of 400–500 m. Farther north, a strong eddy feature is visible along the western section. Along the western section, the height differences calculated from the altimetry are similar to the height differences produced by the inverse method. The results of the research show that 1) the Bernoulli inverse method produces a valid geostrophic velocity field, 2) altimeter data constrains the inverse method, and 3) the initial ERS-1 altimeter data are of good quality if handled carefully.

Abstract

Two triangular hydrographic surveys were conducted in the Iceland-Faroes region with sampling corresponding to the ERS-1 3-day commissioning-phase orbit. The CTD, XBT, and ADCP data show a very active frontal region changing on the order of days. Likewise, the altimetric and infrared data also show a highly variable region. The CTDIXBT data and the altimetric data are synergistically combined in an implementation of the Bernoulli inverse method to calculate velocity fields. A priori information for the inverse are the ERS-1 altimeter height differences. The method produces a velocity field much different from that using a strict reference depth of 800 m for a level of no motion. Velocities of 15–20 cm s−1 flow eastward along the shelf at a depth of 400–500 m. Farther north, a strong eddy feature is visible along the western section. Along the western section, the height differences calculated from the altimetry are similar to the height differences produced by the inverse method. The results of the research show that 1) the Bernoulli inverse method produces a valid geostrophic velocity field, 2) altimeter data constrains the inverse method, and 3) the initial ERS-1 altimeter data are of good quality if handled carefully.

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