Publication Date:
2024-02-21
Description:
〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Bottom‐current related sediments have been commonly used for paleoceanographic reconstructions. However, the strength and variability of bottom currents are poorly understood and thus the processes that control sedimentation in deep environments are not clear. In this study, we focus on the Drake Passage, which is connected to the Antarctic Circumpolar Current, that has a major impact on the global climate. We studied the intensity and variability of bottom currents and how they are related to sedimentary processes. For this purpose, we used 27‐years from GLORYS12 Mercator Ocean reanalysis at high resolution to evaluate the bottom current dynamics. Geophysical data and surface grain size measurements were used to identify the type of sediment deposits. Our results show that the dynamics of bottom currents is disconnected from the sea surface dynamics, and bottom circulation is strongly controlled by the rough topography of the Drake Passage. The patterns for the first modes of bottom‐current variability are related to the local topography and seem to generally control the distribution of contourites. The second and third EOF modes show patterns in the bottom currents that differ from the mean field, and they may affect the rate of erosion and deposition differently. Time series of bottom currents reveals multiple high‐speed current events, but contourite drifts seem to accumulate preferentially in zones of slow and stable bottom currents. Our study highlights the potential of using ocean reanalysis to better constrain bottom currents in zones of scarce data and to plan future campaigns of direct measurements.〈/p〉
Description:
Plain Language Summary: As a result of its unique geography, the Southern Ocean contains the largest ocean current in the world ocean, the Antarctic Circumpolar Current (ACC). The Drake Passage (DP) is the major geographic constriction for the ACC and exerts a strong control on the exchange of physical, chemical, and biological properties between the ocean basins. Yet, the bottom dynamics and the relation with sedimentary processes remain to be studied. We analyzed the currents flowing near the seafloor using a high resolution (1°/12°) reanalysis and compared the bottom dynamics with the characteristics of the seafloor sediments obtained using geophysical data sets and sediment cores. We found that the complex topography of the DP plays an essential role in bottom‐current dynamics and that the circulation pattern near the seabed is often different from the sea surface circulation. The largest sediment deposits are located in the zones with weakest bottom current activity.〈/p〉
Description:
Key Points:
〈list list-type="bullet"〉
〈list-item〉
〈p xml:lang="en"〉The variability of bottom currents in the Drake Passage is described using the ocean reanalysis GLORYS12〈/p〉〈/list-item〉
〈list-item〉
〈p xml:lang="en"〉Bottom currents are strongly controlled by the topography and are often disconnected from the surface circulation〈/p〉〈/list-item〉
〈list-item〉
〈p xml:lang="en"〉Sedimentary processes are dominated by the influence of local topography and bottom currents〈/p〉〈/list-item〉
〈/list〉
〈/p〉
Description:
Deutscher Akademischer Austauschdienst
http://dx.doi.org/10.13039/501100001655
Description:
https://doi.org/10.48670/moi-00021
Description:
https://doi.org/10.17882/59800
Description:
https://doi.org/10.1594/PANGAEA.864950
Description:
https://doi.org/10.1594/PANGAEA.864807
Description:
https://doi.org/10.1594/PANGAEA.862944
Description:
https://doi.pangaea.de/10.1594/PANGAEA.907140
Description:
https://doi.org/10.1038/s41597-022-01366-7
Description:
http://www.eoas.ubc.ca/7Erich/map.html
Description:
https://odv.awi.de/
Keywords:
ddc:551.46
;
Drake Passage
;
bottom currents
;
sedimentary features
;
Southern Ocean
;
bathymetry
Language:
English
Type:
doc-type:article
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