Observations at 11°S in the Atlantic
Rebecca Hummels
1, Peter Brandt
1, Marcus Dengler
1, Jürgen Fischer
1, M. Araujo
2, R. Kopte
1, J. Herrford
1, P. Tchipilanga
31GEOMAR Helmholtz Zentrum für Ozeanforschung, Kiel, Germany
2DOCEAN Department of Oceanography UFPE Refice, Brazil
3INIP Instituto National de Investigacao Pesqueira, Luanda, Angola
SAMOC Workshop at Ocean Sciences Meeting 2016, New Orleans, USA, 21.02.2016
Circulation within the tropical Atlantic
Atlantic thermohaline circulation (ATHC) Shallow Subtropical-tropical Cells (STC)
11°S
Observations at 5°S and 11°S between 1990-2004:
Observations:
• 9 research cruises:
repeatedly occupied the 5°S and 11°S section
• Mooring array at 11°S 2000-2004
Schott et al. 2005
Observations at 11°S between 2000-2004: Mean state
remake of Schott et al. 2005
Observations at 11°S between 2000-2004: Variability
NBUC:
• strong short term variability
• seasonal cycle <2.5 Sv
DWBC:
• even stronger short term variability
• Spectral peak at 60-70 days period associated with deep eddies
Schott et al. 2005
Observations at 11°S between 2000-2004:
Break up of DWBC in to deep eddies at around 8°S
Dengler et al. 2004
Plans within “RACE“
• estimate the northward transport of central and intermediate water within the NBUC as part of the AMOC and STC on interannual to decadal time scales
• estimate the northward transport of central and intermediate water within the NBUC as part of the AMOC and STC on interannual to decadal time scales
• analyze the connection between transport variations in the western boundary current system of the tropical South Atlantic (warm and cold water route) and the variability of the subpolar North Atlantic with
respect to the signal propagation within the AMOC
Plans within “RACE“
• estimate the northward transport of central and intermediate water within the NBUC as part of the AMOC and STC on interannual to decadal time scales
• analyze the connection between transport variations in the western boundary current system of the tropical South Atlantic (warm and cold water route) and the variability of the subpolar North Atlantic with
respect to the signal propagation within the AMOC
• analyze the propagation of water mass anomalies in the AMOC, which can e.g. be caused by the variability in the Agulhas leakage
Plans within “RACE“
• estimate the northward transport of central and intermediate water within the NBUC as part of the AMOC and STC on interannual to decadal time scales
• analyze the connection between transport variations in the western boundary current system of the tropical South Atlantic (warm and cold water route) and the variability of the subpolar North Atlantic with
respect to the signal propagation within the AMOC
• analyze the propagation of water mass anomalies in the AMOC, which can e.g. be caused by the variability in the Agulhas leakage
• analyze the connection between assessed NBUC variability at 11° S and EUC variability at 23°W on the equator and its relevance for climate
variability
Plans within “RACE“
• estimate the northward transport of central and intermediate water within the NBUC as part of the AMOC and STC on interannual to decadal time scales
• analyze the connection between transport variations in the western boundary current system of the tropical South Atlantic (warm and cold water route) and the variability of the subpolar North Atlantic with
respect to the signal propagation within the AMOC
• analyze the propagation of water mass anomalies in the AMOC, which can e.g. be caused by the variability in the Agulhas leakage
• analyze the connection between assessed NBUC variability at 11° S and EUC variability at 23°W on the equator and its relevance for climate
variability
• investigate the variability of the basin-wide (S)AMOC at 11°S
Plans within “RACE“
• estimate the northward transport of central and intermediate water within the NBUC as part of the AMOC and STC on interannual to decadal time scales
• analyze the connection between transport variations in the western boundary current system of the tropical South Atlantic (warm and cold water route) and the variability of the subpolar North Atlantic with
respect to the signal propagation within the AMOC
• analyze the propagation of water mass anomalies in the AMOC, which can e.g. be caused by the variability in the Agulhas leakage
• analyze the connection between assessed NBUC variability at 11° S and EUC variability at 23°W on the equator and its relevance for climate
variability
• investigate the variability of the basin-wide (S)AMOC at 11°S
How do we plan to achieve this?
Collaboration with SFB754 at GEOMAR
Collaboration with PREFACE/SACUS at GEOMAR
Collaboration with PREFACE/SACUS
Western boundary current meter array
Eastern boundary current meter array
11°S
AMOC estimate at 11°S
Geostrophy Geostrophy
WBWB EBEB
Ekman Ekman
WB EB
Recent/upcoming cruises
M119: 8.9.2015 (Sao Vicente, Cape Verde) -13.10.2015 (Recife, Brazil)
M120: 17.10.2015 (Recife, Brazil)
-18.11.2015 (Walvis Bay, Namibia)
M130: 25.8.2016 (Sao Vicente, Cape Verde) -30.09.2016 (Recife, Brazil)
M131: 03.10.2016 (Recife, Brazil)
-08.11.2016 (Walvis Bay, Namibia)
MXXX: spring 2018
2016 2018
2015
Recent/Future moored observations
Last recovery 2018 from GEOMAR (end of RACE II)
after 2018: Collaboration with Brazil ?!
Western boundary ADCP observations Eastern boundary ADCP observations Last recovery 2018 from GEOMAR
Possibiliy of prolongation
Publications/Data Status
Hummels et al. (2015), Interannual to decadal changes in the western boundary circulation in the Atlantic at 11°S, Geophys. Res. Lett., 42, 7615–7622, doi:10.1002/2015GL065254.
Herrford et al. (2016), The Pathways and Property Changes of Deep and Bottom Waters in the Western Tropical Atlantic, submitted to Deep Sea Reseach
