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

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 CTD/XBT 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 in~erse method. The results of the research show that I ) 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.