科研之友
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摘要
The meridional overturning circulation (MOC) in the North Atlantic plays a major role in the transport of heat from low to high latitudes. In this study, we combine recent measurements of currents from the surface to >700 m from a shipboard acoustic Doppler current profiler with Argo profiles (to 2000 m) to estimate poleward volume, heat, and freshwater flux at 59.5 degrees N between Greenland and Scotland. This is made possible thanks to the vessel Nuka Arctica that operates on a 3 week schedule between Greenland and Denmark. For the period late 2012 to early 2016, the deseasoned mean meridional overturning circulation reaches a 18.4 +/- 3.4 Sv maximum at the sigma(theta) = 27.55 kg m(-3) isopycnal, which varies in depth from near the surface in the western Irminger Sea to 1000 m in Rockall Trough. The total heat and freshwater fluxes across 59.5 degrees N = 399 +/- 74 TW and -0.20 +/- 0.04 Sv, where the uncertainties are principally due to that of the MOC. Analysis of altimetric sea surface height variations along exactly the same route reveals a somewhat stronger geostrophic flow north during this period compared to the 23 year mean suggesting that for a long-term mean the above flux estimates should be reduced slightly to 17.4 Sv, 377 TW, and -0.19 Sv, respectively, with the same estimate uncertainties. The ADCP program is ongoing.
- 出版日期2017-7
