The Jan Mayen Current from 1989 and 1990 summer data

Abstract

As part of the Greenland Sea Project, a hydrographic survey consisting of 45 CTD stations was conducted in the vicinity of the Jan Mayen Current (JMC) in August 1990 aboard the USNS BARTLETT to further characterize and quantify circulation of the JMC. Comparisons were made with a similar survey performed in September 1989. In the summer of 1990, as in 1989, the JMC appears to be both a portion of the East Greenland Current (EGC) flowing eastward to close the Greenland Sea Gyre (GSG) and an anticyclonic meander in the EGC flow north of Jan Mayen. Geostrophic velocities and transports were similar for 1990 and 1989 with typical near-surface speeds of 3 cm/s slowing to 1 cm/s at depth. The total input flow to the JMC from the EGC is estimated at 1.45 Sv for August 1990 compared to 2 Sv during September 1989. Baroclinic calculations for 1990 data indicate that the meander portion of the JMC is concentrated in the upper waters (approx 100 m) with the result that 44% of the upper layer and 25% of lower layer (approx 100 - 1000 m) flow contributes to the JMC meander. The remainder, 56% from the surface and 75% from the lower layer, continues eastward as throughput to the GSG. Similarly, in 1989, it was determined that about half of the upper layer flow is involved in the meander with flow becoming more easterly with depth.