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Abyssal Transport Variations in the Southwest South Atlantic: First Insights From a Long‐Term Observation Array at 34.5°S
Author(s) -
Valla Daniel,
Piola Alberto R.,
Meinen Christopher S.,
Campos Edmo
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl082740
Subject(s) - abyssal zone , geology , geostrophic wind , hydrography , barotropic fluid , boundary current , zonal and meridional , continental shelf , climatology , current meter , geostrophic current , oceanography , boundary layer , abyssal plain , geodesy , ocean current , physics , geomorphology , structural basin , thermodynamics
The zonal structure and time variability of the abyssal flow (below 3,000 dbar) in the South Atlantic western boundary is investigated using a combination of moored observations and simultaneous hydrographic/velocity sections at 34.5°S during 2009–2018. Moored direct velocity measurements near the bottom show strong variability with a peak‐to‐peak range exceeding 80 cm/s and dominant signals at times scales of 1–2 months. Daily time series of the meridional absolute geostrophic volume transport computed from the moorings reveals a highly energetic record with a temporal standard deviation of 8.3 Sv and peak‐to‐peak variations of 49 Sv, suggesting a significant contribution of the abyssal layer flows to the Deep Western Boundary Current time variability. The absolute transport is mostly driven by barotropic changes that are dominated by variations in the bottom pressure ~650 km away from the continental slope.