Interannual Variations of Volume Transport in the Western Labrador Sea Based on TOPEX/Poseidon and WOCE Data

Abstract

The interannual variations of volume transport in the western Labrador Sea are estimated using six years of TOPEX/Poseidon altimeter data and hydrographic data from a WOCE repeat section and a method based on the linear momentum equation in which the sea surface is the level of known motion. The interannual variation of the total transport in spring/summer has a range of 6.2 Sv (Sv ≡ 106 m3 s−1) and is positively correlated with the fall/winter North Atlantic Oscillation (NAO) index and wind patterns in the northwest North Atlantic. The total transport anomaly is decomposed into a barotropic and a baroclinic component. The interannual change of the barotropic transport is similar to that of the total transport, and is positively correlated with the fall/winter NAO index. The baroclinic transport anomaly, in comparison, has a smaller magnitude and the opposite sign. The authors conjecture that the deepened Icelandic low in high index years generates a strong cyclonic wind stress curl, which in turn creates a strong divergence and a large upward sea surface slope toward the Greenland coast, resulting in an intensified Labrador Sea circulation.