World Library  


Add to Book Shelf
Flag as Inappropriate
Email this Book

Agulhas Ring Injection Into the South Atlantic During Glacials and Interglacials : Volume 4, Issue 3 (30/09/2008)

By Zharkov, V.

Click here to view

Book Id: WPLBN0004020358
Format Type: PDF Article :
File Size: Pages 15
Reproduction Date: 2015

Title: Agulhas Ring Injection Into the South Atlantic During Glacials and Interglacials : Volume 4, Issue 3 (30/09/2008)  
Author: Zharkov, V.
Volume: Vol. 4, Issue 3
Language: English
Subject: Science, Ocean, Science
Collections: Periodicals: Journal and Magazine Collection, Copernicus GmbH
Historic
Publication Date:
2008
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications

Citation

APA MLA Chicago

Nof, D., & Zharkov, V. (2008). Agulhas Ring Injection Into the South Atlantic During Glacials and Interglacials : Volume 4, Issue 3 (30/09/2008). Retrieved from http://www.worldlibrary.net/


Description
Description: Geophysical Fluid Dynamics institute, Florida State University, USA. Recent proxies suggest that, at the end of the last glacial, there was a significant increase in the injection of Agulhas rings into the South Atlantic (SA). This brought about a dramatic increase in the salt-influx (from the Indian Ocean) into the SA helping re-start the then-collapsed meridional overturning cell (MOC), leading to the termination of the Younger Dryas (YD). Here, we propose a mechanism through which large variations in ring production take place.

Using nonlinear analytical solutions for eddy shedding, we show that there are restricted possibilities for ring detachment when the coast is oriented in the north-south direction. We define a critical coastline angle below which there is rings shedding and above which there is almost no shedding. In the case of the Agulhas region, the particular shape of the African continent implies that rings can be produced only when the retroflection occurs beyond a specific latitude where the angle is critical. During glaciation, the wind stress curl (WSC) vanished at a latitude lower than that of the critical angle, which prohibited the retroflection from producing rings. When the latitude at which the WSC vanishes migrated poleward towards its present day position, the corresponding coastline angle decreased below the critical angle and allowed for a vigorous production of rings.

Simple process-oriented numerical simulations (using the Bleck and Boudra model) are in satisfactory agreement with our results and enable us to affirm that, during the glacials, the behavior of the Agulhas Current (AC) was similar to that of the modern East Australian Current (EAC), for which the coastline slant is supercritical.


Summary
Agulhas ring injection into the South Atlantic during glacials and interglacials

Excerpt
Andrews, J. C. and Scully-Power, P.: The structure of an East Australian Current anticyclonic eddy, J. Phys. Oceanogr., 6, 756–765, 1976.; Arruda, W. Z., Nof, D., and O'Brien, J. J.: Does the Ulleung eddy owe its existence to \textit$\beta $ and nonlinearities?, Deep-Sea Res., 51, 2073–2090, 2004.; Bard, E.: Climate shock: abrupt changes over millennial time scales, Phys. Today, 55, 32–38, 2002.; Berger, W. H. and Wefer, G.: Expeditions into the past: paleoceanographic studies in the South Atlantic, pp. 35–156, Springer-Verlag, Berlin-Heidelberg, 1996.; Bleck, R. and Boudra, D.: Wind-driven spin-up in eddy resolving ocean models formulated in isopycnic and isobaric coordinates, J. Geophys. Res., 91, 7611–7621, 1986.; Bostock, H. C., Opdyke, B. N., Gagan, M. K., Kiss, A. E., and Fifield, L. K.: Glacial/interglacial changes in the East Australian current, Clim. Dynam., 26, 645–659, 2006.; Byrne, A. D., Gordon, A. L., and Haxby, W. F.: Agulhas eddies: A synoptic view using geosat ERM data, J. Phys. Oceanogr., 25, 902–917, 1995.; Chassignet, E. P. and Boudra, D. B.: Dynamics of the Agulhas retroflection and ring formation in a numerical model. II. Energetics and ring formation, J. Phys. Oceanogr., 18, 304–319, 1988.; de Ruijter, W. P. M.: Asymptotic analysis of the Agulhas and Brazil Current systems, J. Phys. Oceanogr., 12, 361–373, 1982.; de Ruijter, W. P. M., Biastoch, A., Drijfhout, S. S., Lutjeharms, J. R. E., Matano, R. P., Pichevin, T., van Leeuwen, P. J., and Weijer, W.: Indian-Atlantic interocean exchange: Dynamics, estimation and impact, J. Geophys. Res., 104, 20 885–20 910, 1999.; Esper, O., Versteegh, G. J. M., Zonneveld, K. A. F., and Willems, H.: A palynological reconstruction of the Agulhas Retroflection (South Atlantic Ocean) during the Late Quaternary, Global Planet. Change, 41, 31–62, 2004.; Gasse, F.: Hydrological changes in the African tropics since the Last Glacial Maximum, Quat. Sci. Rev., 19, 189–211, 2000.; Goni, G. J., Garzoli, S. L., Roubicek, A. J., Olson, D. B., and Brown, O. B.: Agulhas ring dynamics from TOPEX/POSEIDON satellite altimeter data, J. Mar. Res., 55, 861–883, 1997.; Gordon, A. L., Lutjeharms, J. R. E., and Gründlingh, M. L.: Stratification and circulation at the Agulhas Retroflection, Deep-Sea Res., 34, 565–599, 1987.; Howard, W. R. and Prell, W. L.: Late quaternary surface circulation of the southern Indian Ocean and its relationship to orbital variation, Paleoceanogr., 7, 79–117, 1992.; Kawagata, S.: Tasman front shifts and associated paleoceanographic changes during the last 250,000 years: foraminiferal evidence from the Lord Howe Rise, Mar. Micropal., 41, 167–191, 2001.; Knorr, G. and Lohmann, G.: Southern Ocean origin for the resumption of the Atlantic overturning circulation during deglaciation, Nature, 424, 532–536, 2003.; Lutjeharms, J. R. E.: The exchange of water between the South Indian and South Atlantic Oceans, in: The South Atlantic: Present and Past Circulation, edited by: Wefer, G., Berger, W., and Sielder, G., pp. 125–162. Springer-Verlag, Berlin-Heidelberg, 1996.; Lutjeharms, J. R. E.: The Agulhas Current, Springer-Verlag, Berlin-Heidelberg-New York, XIV, 330 p., 2006.; Martinez, J. I.: Late Pleistocene palaeoceanography of the Tasman Sea: implications for the dynamics of the warm pool in the western Pacific, Palaeogreogr. Palaeoclimatol. Palaeoecol., 112, 19–62, 1994.; Martinez, J. I., de Deckker P., and Barrows, T. T.: Palaeoceanography of the western Pacific warm pool during the last glacial maximum: long-term climatic monitoring of the maritime continent, in: Bridging Wallace's line, edited by: Kershaw, P., Bruno, D., Tapper, N., Penny, D., and Brown, J., Adv. Geoecol., 34, 147–172, 2002.; McDonagh, E. L., Heywood, K. J., and Meredith, M. P.: On the structure, paths, and fluxes associated with Agulhas rings, J. Geophys. Res., 104, 21 007–21 020, 1999.; Nilsson, C. S., Andrews, J. C., and Scully-Power, P.: Observation of eddy formation off East Australia, J. Phys. Ocea

 

Click To View

Additional Books


  • Structure of Phytoplankton (Continuous P... (by )
  • Upper Layer Current Variability in the C... (by )
  • Observed Decline of the Atlantic Meridio... (by )
  • Regime Changes in Global Sea Surface Sal... (by )
  • Liquid Export of Arctic Freshwater Compo... (by )
  • Temporal Variations of Zooplankton Bioma... (by )
  • Atmospheric Forcing of Dsow Salinity : V... (by )
  • Assessment of Meris Ocean Color Data Pro... (by )
  • A Century of Sea Level Data and the Uk's... (by )
  • Estimates of Radiance Reflected Towards ... (by )
  • The Mediterranean is Becoming Saltier : ... (by )
  • A Comparison Between Vertical Motions Me... (by )
Scroll Left
Scroll Right

 



Copyright © World Library Foundation. All rights reserved. eBooks from World Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.