التفاصيل البيبلوغرافية
| العنوان: |
The North Atlantic Current and its Volume and Freshwater Transports in the Subpolar North Atlantic, Time Period 1993–2016. |
| المؤلفون: |
Stendardo, I., Rhein, M., Steinfeldt, R. |
| المصدر: |
Journal of Geophysical Research. Oceans; Sep2020, Vol. 125 Issue 9, p1-23, 23p |
| مصطلحات موضوعية: |
MERIDIONAL overturning circulation, HILBERT-Huang transform, FRESH water, WESTERLIES, OCEAN |
| مستخلص: |
The North Atlantic Current (NAC) supplies the subpolar gyre with warm and saline water from the subtropics as part of the upper branch of the Atlantic Meridional Overturning Circulation (AMOC). In the context of climate changes, the North Atlantic Ocean is one of the key regions to investigate the variability of the overturning circulation in which salinity and freshwater variability are playing a central role. Through the gravest empirical mode (GEM) method, we reconstructed salinity and velocity fields in the same spatiotemporal resolution as the sea surface height (SSH) product. The time series of salinity, freshwater, and volume transport are characterized by strong interannual variability related to most of the recently developed subpolar gyre indices. The variability of the freshwater transport in the study area is as high or even higher than the freshwater fluxes from the Arctic Ocean and thus needs to be considered for the impact of freshwater on the subpolar North Atlantic. Our analysis also revealed that the NAC import into the subpolar gyre is not only occurring in the western Atlantic close to the western boundary current. One o the NAC branches that forms at the Mann Eddy contributes about 15% of the volume transport and 28% of the freshwater transport crossing from the western into the eastern Atlantic north of 45°N. This branch has not been subject to the strong lateral mixing with freshwater at the western boundary, and thus, the salinity of this NAC pathway is higher than the one at the western boundary. Plain Language Summary: The northward prolongation of the Gulf Stream is called North Atlantic Current (NAC). The NAC transports warm and salty water from the subtropics to the north, and part of it even reaches the Arctic Ocean. Up to now, the pathways north of 40°N and their strengths and fluctuations are only poorly known. In this study, we used satellite data and measurements in the ocean to calculate the amount of water (volume transport) and salt (here expressed as negative salinity transport and dubbed freshwater transport) between 40°N and 53°N. Our results show that all transports are very variable during the time period from 1993 to 2016. The fluctuation of the NAC freshwater transport is comparable with the amount of freshwater coming from the Arctic Ocean into our study region and thus cannot be neglected. We also saw that the NAC splits into several branches that cross from the western into the eastern Atlantic Ocean. It has been often considered that the southernmost branches turn back to the subtropics. Our results show, however, that some fraction of them instead flows into the eastern subpolar region and influences the amount of salinity there. Key Points: North Atlantic Current branches forming at the Mann Eddy contribute to the salinity distribution in the subpolar eastern North AtlanticTime series of salinity, freshwater, and volume transport show strong variability related to most of the subpolar gyre indicesNorth Atlantic freshwater transport variability is as high or higher than the fluxes from the Arctic ocean [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
Complementary Index |
