Transport of the Norwegian Atlantic Current as determined from satellite altimetry

Abstract

Relatively warm and salty North Atlantic surface waters flow through the Faeroe‐Shetland Channel into the higher latitudes of the Nordic Seas, preserving an ice‐free winter environment for much of the exterior coast of northern Europe. In this study, we have monitored this flow along the Norwegian coast using GEOSAT altimetry on two ascending arcs during the Exact Repeat Mission in 1987–1989. Concurrent undertrack CTD surveys were used to fix a reference surface for the altimeter‐derived sea surface height (SSH) anomalies, in effect creating time series of alongtrack surface dynamic height topographies. Climatologic CTD casts were then used, with empirical orthogonal function (EOF) analysis, to derive relationships between historical surface dynamic heights and vertical temperature and salinity profiles. Applying these EOF relationships to the altimeter signals, we calculated mean transports of volume, heat and salt at approximately 2.9 Sverdrups, 8.1 × 1011 KCal/s and 1.0 × 108 Kg/s, respectively. Although strong variability occurred, a clear seasonal signal could be seen with summer to winter variations of about 50% of the means. Maximum transports occurred in February/March and minimum in July/August.