Figure 2 - uploaded by Silvia L. Garzoli
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Map of the South Atlantic and Southern Ocean, including the two principal choke point regions, the Drake Passage and south of South Africa, with the current and proposed locations of instrument deployments and the institutes leading the corresponding associated projects.
Source publication
While the North Atlantic is the sole provider of North Atlantic Deep Water (NADW) to the global ocean the
South Atlantic is also the sole recipient for upper and bottom waters flowing into the North Atlantic to balance the NADW export. Export of NADW to other ocean basins is compensated for by net northward flow of surface, intermediate and bottom...
Context in source publication
Context 1
... May 8-10, 2007 a workshop was held in Buenos Aires, Argentina to discuss the need for measuring the components of the global meridional overturning circulation in the South Atlantic. The meeting gathered a diverse group of scientists from Argentina, Brazil, France, Germany, Italy, Russia, Uruguay, United Kingdom, and the United States all of whom were working or had plans to work in the South Atlantic region. Copies of the presentations that were made at the workshop and a complete workshop report are available on the NOAA-AOML web site at www.aoml.noaa.gov/phod/SAMOC/. Some of the key results of the workshop were: • Meridional overturning circulation variability can be linked to 30oS/33oS heat transport but over longer time scales than surface fluxes • Some discernable changes in sea-surface temperature appear to be linked to the eastern boundary circulation • Direct measurements of Western Boundary Currents are critical in order to observe accurately either the meridional overturning circulation or heat transport • Very little is currently in place or even proposed that will capture all the meridional overturning circulation as a sustained observing system The Second SAMOC Workshop took place in Paris France, July 1 and 2, 2009. The main objectives of the workshop were: • Review the main achievements made since May 2007 • Review and update current collaborations • Further coordinate the efforts with the Southern Ocean Observing System community and the paleo community. • To agree and design a poster to be presented at OceanObs’09 • To review the South Atlantic component of the AMOC White paper for OceanObs’09. The meeting included presentations detailing new advances in science and in observations in the South Atlantic. The importance of monitoring the South Atlantic was emphasized based on modeling results that demonstrated: 1) the SA, the sole generator of the compensating flows for the southward flowing NADW, is not a passive ocean. Water mass transformations occurred in the regions of high variability, i.e., the Confluence and the Cape Basin. Therefore observations of the AMOC are need in the Subtropical South Atlantic. 2) The variability in those regions is highly correlated to the variability of the winds in the South Pacific and Indian Oceans. Therefore, in order to understand the origins of this variability, observations in the SA should be related to observations or modeling results in the adjacent basins. The main discussion focused on what parameters are needed to be measured and what were the best locations to observe them. It was agreed to have the next meeting in Brazil in April 2010. The SAMOC group already started with ongoing collaborative projects that include: 1) the undertaking of proof-of-concept numerical studies to design a monitoring system capable of determining the time-variable overturning in the South Atlantic and its horizontal fluxes of heat and freshwater 2) a number of coordinated observing efforts such as the GoodHope international effort and the already deployed arrays of C-PIES and PIES along the high resolution NOAA-AOML XBT AX18 zonal line (see figure 2 here below for a summary of ongoing/planned ...
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Citations
... Despite the efforts made in the South Atlantic Ocean, the current in situ observations are not able to monitor, for example, large-scale inter-basin flows, heat transfer, fresh water, mass and other quantities relevant to the climate [9]. As expected, Argentina is not alien to this weakness, even with the sea conditions and the richness of its resources. ...
Lakes, rivers, estuaries and ocean waters control many important natural functions at the regional-global level. Hence, integrative and frequent long-term water monitoring is required globally. This paper describes the main features and innovations of a low-cost monitoring buoys network (MBN) deployed in a temperate region of Argentina. The MBN was designed to record extended time series at high-frequency, which is of great value for the scientific community, as well as for decision-makers. In addition, two innovative designs belonging to two versions of moored buoys (i.e. shallow waters and coastal marine waters) were presented. It was shown that the cost of either of two versions of the buoy is low, which can be considered as the main advantage.
... The general public's increased awareness of the physics of climate has been brought about partly by the mounting evidence that climate is indeed undergoing significant variability and change (e.g., data showing increases of global temperature and sea level rise during the last century), and partly by the predictions based upon model results about the consequences that such changes might have on societies (IPCC, 2007). It is not always easy to separate fact from fiction, but the paleo-climate record indeed suggests that past shutdowns of the MOC triggered ice ages with dramatic decreases of the temperatures in western Europe and beyond (IPCC, 2007; Speich et al., 2010). The perceived fragility of the climate system has prompted a flurry of new studies whose conclusions are, if not alarming, at least worrisome. ...
... At present there is only one quasi-comprehensive monitoring system of the AMOC in the northern North Atlantic: the RAPID/MOCHA array in conjunction with the observations of the warm, shallow limb in the Florida Current/Gulf Stream and of the Deep Western Boundary Current (DWBC) started in the early 1980s off Florida (Baringer and Larsen, 2001; Meinen et al. 2006 )—provided the basin-wide integrated strength and vertical structure of the Atlantic Meridional Overturning Circulation (AMOC) at 26.51N (Cunningham et al., 2007; Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/dsr2 Deep-Sea Research II 0967-0645/$ -see front matter Published by Elsevier Ltd. doi:10.1016/j.dsr2.2010 .10.063 Kanzow et al., 2007 ). ...
... .10.063 Kanzow et al., 2007 ). Other attempts to monitor the same components are located in other parts of the North Atlantic (e.g., the Denmark Straits overflow); a small pilot effort recently started in the South Atlantic (Speich et al., 2010). These systems were designed to observe some of the important components of the AMOC that can, in turn, be used to verify and assimilate into models (Østerhus et al., 2005; Srokosz, 2004; Baringer and Garzoli, 2007). ...
As a contribution to the OCEANOBS99 objectives, we give a brief description of the present knowledge of the South Atlantic and identify some key processes and areas which need to be monitored in order to understand the role of that part of the ocean in the global climate. Included are suggestions of strategies for a first approximation towards an ocean climate monitoring system in the South Atlantic.
The eastern side of the South Atlantic Meridional overturning circulation
Basin-wide Array (SAMBA) along 34.5° S is used to assess the
nonlinear, mesoscale dynamics of the Cape Basin. This array presently
consists of current meter moorings and bottom mounted Current and Pressure recording Inverted Echo
Sounders (CPIES)
deployed across the continental slope. These data, available from September
2014 to December 2015, combined with satellite altimetry allow us to
investigate the characteristics and the impact of mesoscale dynamics on local
water mass distribution and cross-validate the different data sets. We
demonstrate that the moorings are affected by the complex dynamics of the
Cape Basin involving Agulhas rings, cyclonic eddies and anticyclonic eddies
from the Agulhas Bank and the South Benguela upwelling front and filaments.
Our analyses show that exchange of water masses happens through the advection
of water by mesoscale eddies but also via wide water mass intrusions
engendered by the existence of intense dipoles. These complex dynamics induce
strong intra-seasonal upper-ocean velocity variations and water mass
exchanges between the shelf and the open ocean but also across the
subantarctic and subtropical waters. This work presents the first independent
observations comparison between full-depth moorings and CPIES data sets
within the eastern South Atlantic region that gives some evidence of eastern
boundary buoyancy anomalies associated with migrating eddies. It also
highlights the need to continuously sample the full water depth as
inter-basin exchanges occur intermittently and affect the whole water column.
Two ocean general circulation models are used to test the ability of geostrophic velocity measurement systems to observe the meridional overturning circulation (MOC) and meridional heat transport (MHT) in the South Atlantic. Model sampling experiments are conducted at five latitudes (between 15 degrees and 34.5 degrees S) spanning the range of extratropical current regimes in the South Atlantic. Two methods of estimating geopotential height anomalies and geostrophic velocities are tested, simulating dynamic height moorings (T-S array) and current and pressure recording inverted echo sounders (CPIES) deployed within the models. The T-S array accurately reproduces the MOC variability with a slight preference for higher latitudes, while the CPIES array has skill only at higher latitudes resulting from the increased geopotential height anomaly signal. Whether direct model velocities or geostrophic velocities are used, MHT and the MOC are strongly correlated, and successful reconstruction of MHT only occurs when there is skill in the MOC reconstructions. The geopotential height anomaly signal is concentrated near the boundaries along 34.5 degrees S, suggesting that this is an advantageous latitude for deployment of an in situ array. Four reduced arrays that build upon the sites from two existing pilot arrays along 34.5 degrees S were examined. For these realistically sized arrays, the MOC and MHT reconstructions from the T-S and CPIES arrays have comparable skill, and an array of approximately 20 instruments can be effectively used to reproduce the temporal evolution and vertical structure of the MOC and MHT.
