Variability of the Atlantic inflow to the Nordic Seas and its causes inferred from observations of sea surface height

Abstract

We investigate the potential to use sea surface height observed with satellites and tide gauges to explore and to estimate the variability of volume transport of Atlantic water to the Nordic Seas. It is shown that the variability of the Atlantic inflow to the Nordic Seas over the Iceland Faroe Ridge (Faroe Current) primarily responds to an oceanic regime dominated by steric height changes in the interior Nordic Seas. In contrast, variations in the Norwegian Atlantic Slope Current measured at the Svinøy section are largely driven by direct wind forcing. Using linear regression analysis, volume transports anomalies were successfully modeled from the leading modes of altimeter-derived sea surface height and reconstructed back in time using sea surface height observations from tide gauges. The reconstructions explain 22% and 38% of the observed variability in the Faroe and Svinøy currents, respectively. For the Svinøy Current, the reconstruction indicates that the volume transport variability is typically of the order ±1 Sv. High inflow around 1983 and low inflow around 1987 coincide with times when respectively warm and cold anomalies passed through the system. © 2012 by the American Geophysical Union.