Transports across the 2002 Greenland‐Portugal Ovide section and comparison with 1997

Abstract

The first Ovide cruise occurred in June–July 2002 on R/V Thalassa between Greenland and Portugal. The absolute transports across the Ovide line are estimated using a box inverse model constrained by direct acoustic Doppler current profiler velocity measurements and by an overall mass balance (±3 Sv, where 1 Sv = 106 m3 s−1) across the section. Main currents are studied and compared to the results of the similar Fourex section performed in August 1997 and revisited here. The meridional overturning cell (MOC) is estimated in two different ways, both leading to a significantly lower value in June 2002 than in August 1997, consistent with the relative strength of the main components of the MOC (North Atlantic Current and deep western boundary current). It has been found that the MOC calculated on density levels is more robust and meaningful than when calculated on depth levels, and it is found to be 16.9 ± 1.0 Sv in 2002 versus 19.2 ± 0.9 Sv in 1997. The 2002 heat transport of 0.44 ± 0.04 × 1015 W is also significantly different from the 0.66 ± 0.05 × 1015 W found in 1997, but it is consistent with the much weaker integrated warm water transport across the section than in 1997.