Hydrodynamics between Africa and Antarctica during Austral Summer of 2008 and 2009: Results of the IPY Project — Oak Academic Publishing
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Hydrodynamics between Africa and Antarctica during Austral Summer of 2008 and 2009: Results of the IPY Project
National Centre for Antarctic and Ocean Research (NCAOR), Earth System Science Organization, Ministry of Earth Sciences, Government of India, New Delhi, India
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National Centre for Antarctic and Ocean Research (NCAOR), Earth System Science Organization, Ministry of Earth Sciences, Government of India, New Delhi, India
1 National Centre for Antarctic and Ocean Research (NCAOR), Earth System Science Organization, Ministry of Earth Sciences, Government of India, New Delhi, India
2 National Centre for Antarctic and Ocean Research (NCAOR), Earth System Science Organization, Ministry of Earth Sciences, Government of India, New Delhi, India
A hydrographic section between Cape Town,South AfricaandIndiaBay,Antarcticawas sampled by deploying expendable CTD probes during the austral summer of 2008 and 2009. In 2009, the Agulhas Retroflection (AR) Front was displaced southward by 1.5° latitude, while the northern and southern Polar Front meandered southward by 1° and 1.4° latitude, respectively, relative to their positions in 2008. Geostrophic transport, relative to1000 m, indicates that Antarctic Circumpolar Current (ACC) flow decreased by 2.5 Sv in 2009 compared to that in 2008. The anticyclones which are detached from the AR facilitates a transport to the southeast Atlantic Ocean ranging between 8 and 12 Sv. Nearly 50% of the ACC transport is confined to the 100 - 500 m layer. A comparison of water mass distribution for 2008 and 2009 suggests that Mode Water distribution was restricted to 42.5°S and 41.9°S, and the Antarctic Surface Water ex° tended to 57.6°S and 46.6°S, respectivel°. In 2009, the along track H eat C ontent (HC) and S alt C ontent (SC) for the upper750 mof the water column decreased each by 1% compared to those in 2008. In the ACC domain, the HC and SC dip by 36% and 40% in 2009, respectively. The HC and SC associated with Agulhas Retroflection Front increase in 2009 by 1% and 2%, respectively, due to an enhanced Agulhas transport of warm and saline water from the tropics by 2%.
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L. Stramma, “The South Indian Ocean Current,” Journal of Physical Oceanography, Vol. 22, No. 4, 1992, pp. 421-430. doi:10.1175/1520-0485(1992)022 2.0.CO;2
A. L. Gordon, “Indian-Atlantic Transfer of Thermohaline Water of the Agulhas Retroflection,” Science, Vol. 227, No. 4690, 1985, pp. 1030-1033. doi:10.1126/science.227.4690.1030
A. L. Gordon, “Interocean Exchange of Thermocline Water,” Journal of Geophysical Research, Vol. 91, No. C4, 1986, pp. 5037-5046. doi:10.1029/JC091iC04p05037
W. P. M. de Ruijter, A. Biastoch, S. S. Drijfhout, J. R. E. Lutjeharms, R. P. Matano, T. Pichevin, P. J. van Leeuwen and W. Weijer, “Indian-Atlantic Interocean Exchange: Dynamics, Estimation and Impact,” Journal of Geophysical Research, Vol. 104, No. C9, 1999, pp. 20885-20910. doi:10.1029/1998JC900099
I. E. Robertson and A. J. Watson, “A Summertime Sink for Atmospheric Carbon Dioxide in the Southern Ocean between 80°W and 80°E,” Deep Sea Research-II, Vol. 42, No. 4-5, 1995, pp. 1081-1091. doi:10.1016/0967-0645(95)00067-Z
M. Schroder and E. Fahrbach, “On the Structure and Transport of the Eastern Weddell Gyre,” Deep-Sea Research-II, Vol. 46, No. 1-2, 1999, pp. 501-527. doi:10.1016/S0967-0645(98)00112-X
A. H. Orsi, W. D. Nowlin and T. Whitworth Jr., “On the Circulation and Stratification of the Weddell Gyre,” Deep-Sea Research-I, Vol. 40, No. 1, 1993, pp. 169-203. doi:10.1016/0967-0637(93)90060-G
W. J. Emery and J. Meincke, “Global Water Masses: Summary and Review,” Oceanologica Acta, Vol. 9, 1986, pp. 383-391.
L. Stramma and J. R. E. Lutjeharms, “The Flow Field of the Subtropical Gyre of the South Indian Ocean,” Journal of Geophysical Research, Vol. 102, No. C3, 1997, pp. 5513-5530. doi:10.1029/96JC03455
S. T. Gille, “Warming of the Southern Ocean since the 1950s,” Science, Vol. 295, No. 5558, 2002, pp. 1275-1277. doi:10.1126/science.1065863
W. Cai, “Antarctic Ozone Depletion Causes an Intensification of the Southern Ocean Super-Gyre Circulation,” Geophysical Research Letters, Vol. 33, No. 3, 2006. doi:10.1029/2005GL024911
J. K. Willis, D. Roemmich and B. Cornuelle, “Combining Altimetric Height with Broadscale Profile Data to Estimate Steric Height, Heat Storage, Subsurface Temperature, and Sea-Surface Temperature Variability,” Journal of Geophysical Research, Vol. 108, No. C9, 2003, p. 3292. doi:10.1029/2002JC001755
Y.-H. Park, L. Gamberoni and E. Charriaud, “Frontal Structure, Water Masses, and Circulation in the Crozet Basin,” Journal of Geophysical Research, Vol. 98, No. C7, 1993, pp. 12361-12385. doi:10.1029/93JC00938
I. M. Belkin and A. L. Gordon, “Southern Ocean Fronts from the Greenwich Meridian to Tasmania,” Journal of Geophysical Research, Vol. 101, No. C2, 1996, pp. 3675-3696. doi:10.1029/95JC02750
M. D. Sparrow, K. J. Heywood, J. Brown and D. P. Stevens, “Current Structure of the South Indian Ocean,” Journal of Geophysical Research, Vol. 101, No. C3, 1996, pp. 6377-6391. doi:10.1029/95JC03750
A. J. Luis and M. Sudhakar, “Upper-Ocean Hydrodynamics along Meridional Sections in the Southwest Indian Sector of the Southern Ocean during Austral Summer 2007,” Polar Science, Vol. 3, No. 1, 2009, pp. 13-30. doi:10.1016/j.polar.2009.03.001
A. H. Orsi, T. Whitworth III and W. D. Nowlin Jr., “On the Meridional Extent and Fronts of the Antarctic Circumpolar Current,” Deep-Sea Research-I, Vol. 42, No. 5, 1995, pp. 641-673. doi:10.1016/0967-0637(95)00021-W
K. Mizuno and T. Watanabe, “Preliminary Results of in-Situ XCTD/CTD Comparison Test,” Journal of Oceanography, Vol. 54, No. 4, 1998, pp. 373-380. doi:10.1007/BF02742621
S. Kizu, H. Onishi, T. Suga, K. Hanawa, T. Watanabe and H. Iwamiya, “Evaluation of the Fall Rates of the Present and Developmental XCTDs,” Deep-Sea Research-I, Vol. 55, No. 4, 2008, pp. 571-586. doi:10.1016/j.dsr.2007.12.011
R. Bailey, A. Gronell, H. Phillips, G. Meyers and E. Tanner, “CSIRO Cookbook for Quality Control of Expendable Bathythermograph (XBT) Data,” CSIRO Marine Laboratories Report 221, CSIRO, Hobert, 1993.
X. Yuan, D. G. Martinson and Z. Dong, “Upper Ocean Thermohaline Structure and Its Temporal Variability in the Southeast Indian Ocean,” Deep-Sea Research-I: Oceanographic Research Papers, Vol. 51, No. 2, 2003, pp. 333-347. doi:10.1016/j.dsr.2003.10.005
Y.-H. Park, E. Charriaud and P. Craneguy, “Fronts, Transport, and Weddell Gyre at 30°E between Africa and Antarctica,” Journal of Geophysical Research, Vol. 106, No. C2, 2001, pp. 2857-2879. doi:10.1029/2000JC900087
A. G. Kostianoy, A. I. Ginzburg, M. Frankignoulle and B. Delille, “Fronts in the Southern Indian Ocean as inferred from Satellite Sea Surface Temperature Data,” Journal of Marine Systems, Vol. 45, No. 1-2, 2004, pp. 55-73. doi:10.1016/j.jmarsys.2003.09.004
http://www.aviso.oceanobs.com
N. Ducet, P.-Y. Le Traon and G. Reverdin, “Global High-Resolution Mapping of Ocean Circulation from TOPEX/ Poseidon and ERS-1 and -2,” Journal of Geophysical Research, Vol. 105, No. C8, 2000, pp. 19477-19498. doi:10.1029/2000JC900063
M. Andres, J.-H. Park, M. Wimbush, X.-H. Zhu, K.-I. Chang and H. Ichikawa, “Study of the Kuroshio/Ryukyu Current System Based on Satellite-Altimeter and in-Situ Measurements,” Journal of Oceanography, Vol. 64, No. 6, 2008, pp. 937-950. doi:10.1007/s10872-008-0077-2
F. J. Wentz, C. L. Gentemann and P. D. Ashcroft, “On-Orbit Calibration of AMSR-E and the Retrieval of Ocean Products,” The 83rd AMS Annual Meeting, Long Beach, 2003.
O. Boebel, J. R. E. Lutjeharms, C. Schmid, W. Zenk, T. Rossby and C. Barron, “The Cape Cauldron: A Regime of Turbulent Inter-Ocean Exchange,” Deep-Sea Research II, Vol. 50, No. 1, 2003, pp. 57-86. doi:10.1016/S0967-0645(02)00379-X
J. R. E. Lutjeharms and W. P. M. de Ruijter, “The Influence of the Agulhas Current on the Adjacent Coastal Ocean: Possible Impacts of Climate Change,” Journal of Marine Systems, Vol. 7, No. 2-4, 1996, pp. 321-336. doi:10.1016/0924-7963(95)00010-0
W. P. M. de Ruijter, P. J. van Leeuwen and J. R. E. Lutjeharms, “Generation and Evolution of Natal Pulses: Solitary Meanders in the Agulhas Current,” Journal of Physical Oceanography, Vol. 29, No. 12, 1999, pp. 3043-3055. doi:10.1175/1520-0485(1999)029 2.0.CO;2
M. Tsugawa and H. Hasumi, “Generation and Growth Mechanism of the Natal Pulse,” Journal of Physical Oceanography, Vol. 40, No. 7, 2010, pp. 1597-1612. doi:10.1175/2010JPO4347.1
J. R. E. Lutjeharms, “The Role of Mesoscale Turbulence in the Agulhas Current System,” Elsevier Oceanography Series, Vol. 50, 1989, pp. 357-372. doi:10.1016/S0422-9894(08)70196-X
C. D. Quartly and M. A. Srokosz, “Seasonal Variations in the Region of the Agulhas Retroflection: Studies with Geosat and FRAM,” Journal of Physical Oceanography, Vol. 23, No. 9, 1993, pp. 2107-2124. doi:10.1175/1520-0485(1993)023 2.0.CO;2
C. J. Koblinsky, “The Global Distribution of f/H and the Barotropic Response of the Ocean,” Journal of Geophysical Research, Vol. 95, No. C3, 1990, pp. 3213-3218. doi:10.1029/JC095iC03p03213
J. R. E. Lutjeharms and J. Cooper, “Interbasin Leakage through Agulhas Current Filaments,” Deep-Sea Research-I, Vol. 43, No. 2, 1996, pp. 213-238. doi:10.1016/0967-0637(96)00002-7
J. Ochoa and P. P. Niiler, “Vertical Vorticity Balance in Meanders Downstream the Agulhas Retroflection,” Journal of Physical Oceanography, Vol. 37, No. 6, 2007, pp. 1740-1744. doi:10.1175/JPO3064.1
D. Stammer and C. Wunsch, “Temporal Changes in the Mesoscale Variability of the Oceans,” Deep-Sea Research-II, Vol. 46, No. 1-2, 1999, pp. 77-108. doi:10.1016/S0967-0645(98)00106-4
N. Anilkumar, A. J. Luis, Y. K. Somayajulu, V. Ramesh Babu, M. K. Dash, S. M. Pednekar, K. N. Babu, M. Sudhakar and P. C. Pandey, “Fronts, Water Masses, and Heat Content Variability in the Western Indian Sector of the Southern Ocean during Austral Summer 2004,” Journal of Marine Systems, Vol. 63, No. 1-3, 2006, pp. 20-34. doi:10.1016/j.jmarsys.2006.04.009
Y.-H. Park, L. Gamberoni and E. Charriaud, “Frontal Structure, Water Masses, and Circulation in the Crozet Basin,” Journal of Geophysical Research, Vol. 98, No. C7, 1993, pp. 12361-12385. doi:10.1029/93JC00938
Y.-H. Park and L. Gamberoni, “Large-Scale Circulation and Its Variability in the South Indian Ocean from TOPEX/POSEIDON Altimetry,” Journal of Geophysical Research, Vol. 100, No. C12, 1995, pp. 24911-24929. doi:10.1029/95JC01962
Y.-H. Park, E. Charriaud and M. Fieux, “Thermohaline Structure of the Antarctic Surface Water/Winter Water in the Indian Sector of the Southern Ocean,” Journal of Marine Systems, Vol. 17, No. 1-4, 1998, pp. 5-23. doi:10.1016/S0924-7963(98)00026-8
J. R. E. Lutjeharms, “Location of Frontal Systems between Africa and Antarctica: Some Preliminary Results,” Deep-Sea Research-I, Oceanography Research Papers, Vol. 32, No. 12, 1985, pp. 1499-1509. doi:10.1016/0198-0149(85)90100-1
J. F. Legeais, S. Speich, M. Arhan, I. J. Ansorge, E. Fahrbach, S. Garzoli and A. Klepikov, “The Baroclinic Transport of the Antarctic Circumpolar Current South of Africa,” Geophysical Research Letters, Vol. 32, No. 24, 2005. doi:10.1029/2005GL023271
S. R. Rintoul, S. Sokolov and J. Church, “A 6 Year Record of Baroclinic Transport Variability of the Antarctic Circumpolar Current at 140°E from Expendable Bathythermograph and Altimetry Measurements,” Journal of Geophysical Research, Vol. 107, 2002, p. 3155.
P. L. Richardson, “Agulhas Leakage into the Atlantic Estimated with Subsurface Floats and Surface Drifters,” Deep-Sea Research-I, Vol. 54, No. 8, 2007, pp. 1361-1389. doi:10.1016/j.dsr.2007.04.010
M. Rouault, P. Penven and B. Pohl, “Warming in the Agulhas Current System since the 1980’s,” Geophysical Research Letters, Vol. 36, No. 12, 2009. doi:10.1029/2009GL037987
D. Byrne, A. L. Gordon and W. Haxby, “Agulhas Eddies: A Synoptic View Using Geosat ERM Data,” Journal of Physical Oceanography, Vol. 25, No. 5, 1995, pp. 902-917. doi:10.1175/1520-0485(1995)025 2.0.CO;2
A. L. Gordon, J. R. E. Lutjeharms and M. L. Gründlingh, “Stratification and Circulation at the Agulhas Retroflection,” Deep-Sea Research-I: Oceanographic Research Papers, Vol. 34, No. 4, 1987, pp. 565-599.
J. R. E. Lutjeharms, “A Quantative Assessment of Year-to-Year Variability in Water Movement in the Southwest Indian Ocean,” Nature, Vol. 239, No. 91, 1972, pp. 59-60.
M. J. Orren, “Hydrology of the South West Indian Ocean,” Investigational Report of the Division for Sea Fisheries of South Africa, Vol. 55, 1966, pp. 1-35.
H. R. Valentine, J. R. E. Lutjeharms and G. B. Brundrit, “The Water Masses and Volumetry of the Southern Agulhas Current Region,” Deep-Sea Research-I, Vol. 40, No. 6, 1993, pp. 1285-1305. doi:10.1016/0967-0637(93)90138-S
A. L. Gordon, “South Atlantic Thermohaline Ventilation,” Deep-Sea Research, Vol. 28, No. 11, 1981, pp. 1239-1264. doi:10.1016/0198-0149(81)90033-9
M. S. McCartney, “Subantarctic Mode Water,” In: M. V. Angel, Ed., A Voyage of Discovery, Pergamon, New York, 1977.
M. S. McCartney, “The Subtropical Recirculation of Mode Waters,” Journal of Marine Research, Vol. 40, 1982, pp. 427-464.
Y.-H. Park, L. Gamberoni and E. Charriaud, “Frontal Structure and Transport of the Antarctic Circumpolar Current in the South Indian Ocean Sector, 40°E-80°E,” Marine Chemistry, Vol. 35, No. 1-4, 1991, pp. 45-62. doi:10.1016/S0304-4203(09)90007-X
A. P. S. Wong, N. L. Bindoff and A. Forbes, “Ocean-Ice Shelf Interaction and Possible Bottom Water Formation in Prydz Bay, Antarctica,” In: S. S. Jacobs and R. F. Weiss, Eds., Ocean, Ice and Atmosphere: Interactions at the Antarctic Continental Margin, Antarctic Research Series, Vol. 75. AGU, Washington DC, 1998.
H. U. Sverdrup, M. W. Johnson and R. H. Fleming, “The Oceans: Their Physics, Chemistry, and General Biology,” Prentice-Hall, Upper Saddle River, 1942.
K. Wyrtki, “Oceanographic Atlas of the International Indian Ocean Expedition,” National Science Foundation, Washington DC, 1971.
T. Whitworth III, A. H. Orsi, S. J. Kim, W. D. Nowlin Jr. and R. A. Locarnini, “Water Masses and Mixing Near the Antarctic Slope Front,” In: S. S. Jacobs and R. F. Weiss, Eds., Ocean, Ice and Atmosphere: Interactions at the Antarctic Continental Margin, Antarctic Research Series, Vol. 75. AGU, Washington DC, 1998, pp. 1-27. doi:10.1029/AR075p0001
E.-P. Lim and I. Simmonds, “Explosive Cyclone Development in the Southern Hemisphere and a Comparison with Northern Hemisphere Events,” Monthly Weather Review, Vol. 130, No. 9, 2002, pp. 2188-2209. doi:10.1175/1520-0493(2002)130 2.0.CO;2
R. G. Peterson, W. D. Nowlin Jr. and T. Whitworth III, “Generation and Evolution of a Cyclonic Ring at Drake Passage in Early 1979,” Journal of Physical Oceanography, Vol. 12, No. 7, 1984, pp. 712-719. doi:10.1175/1520-0485(1982)012 2.0.CO;2
O. Boebel, T. Rossby, J. R. E. Lutjeharms, W. Zenk and C. Barron, “Path and Variability of the Agulhas Return Current,” Deep-Sea Research II, Vol. 50, No. 1, 2003, pp. 35-56. doi:10.1016/S0967-0645(02)00377-6
M. R. Jury, B. M. R. Pathack, C. J. D. W. Rautenbach and J. van Heerden, “Drought over South Africa and Indian Ocean SST: Statistical and GCM Results,” The Global Atmosphere and Ocean System, Vol. 4, No. 1, 1996, pp. 47-63.
W. H. F. Smith and D. T. Sandwell, “Global Seafloor Topography from Satellite Altimetry and Ship Depth Soundings,” Science, Vol. 277, No. 5334, 1997, pp. 1957-1962. doi:10.1126/science.277.5334.1956