Articles | Volume 13, issue 6
https://doi.org/10.5194/os-13-1035-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/os-13-1035-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
07 Dec 2017
Research article |
| 07 Dec 2017
An undercurrent off the east coast of Sri Lanka
Scripps Institution of Oceanography, La Jolla, California, USA
Uwe Send
Scripps Institution of Oceanography, La Jolla, California, USA
Julie L. McClean
Scripps Institution of Oceanography, La Jolla, California, USA
Janet Sprintall
Scripps Institution of Oceanography, La Jolla, California, USA
Luc Rainville
Applied Physics Laboratory, University of Washington, Seattle,
Washington, USA
Craig M. Lee
Applied Physics Laboratory, University of Washington, Seattle,
Washington, USA
S. U. Priyantha Jinadasa
National Aquatic Resources Research and Development Agency (NARA)
Crow Island, Colombo 15, Sri Lanka
Alan J. Wallcraft
Center for Ocean–Atmospheric Prediction Studies (COAPS), Florida State University, Tallahassee, Florida, USA
E. Joseph Metzger
Naval Research Laboratory, Stennis Space Center, Mississippi, USA
Related authors
Arachaporn Anutaliya
Ocean Sci., 19, 335–350, https://doi.org/10.5194/os-19-335-2023, https://doi.org/10.5194/os-19-335-2023, 2023
Short summary
Short summary
To understand the circulation pattern in the Gulf of Thailand (GoT) and the local wind effect, satellite and in situ observations are used. The flow is highly variable at the western boundary and the GoT mouth. Seasonally, it is dominated by the monsoon winds and sea surface level set up by local wind rotation. Surprisingly, interannual variation in the current over each region in the GoT responds to different climate modes (El Niño–Southern Oscillation and the Indian Ocean Dipole) differently.
Arne Bendinger, Sophie Cravatte, Lionel Gourdeau, Luc Rainville, Clément Vic, Guillaume Sérazin, Fabien Durand, Frédéric Marin, and Jean-Luc Fuda
Ocean Sci., 20, 945–964, https://doi.org/10.5194/os-20-945-2024, https://doi.org/10.5194/os-20-945-2024, 2024
Short summary
Short summary
A unique dataset of glider observations reveals tidal beams south of New Caledonia – an internal-tide-generation hot spot in the southwestern tropical Pacific. Observations are in good agreement with numerical modeling output, highlighting the glider's capability to infer internal tides while assessing the model's realism of internal-tide dynamics. Discrepancies are in large part linked to eddy–internal-tide interactions. A methodology is proposed to deduce the internal-tide surface signature.
Clea Baker Welch, Neil Malan, Daneeja Mawren, Tamaryn Morris, Janet Sprintall, and Juliet Clair Hermes
EGUsphere, https://doi.org/10.5194/egusphere-2024-2210, https://doi.org/10.5194/egusphere-2024-2210, 2024
Short summary
Short summary
Marine heatwaves (MHWs) are prolonged periods of extreme ocean temperatures with significant impacts on marine ecosystems. Much research has focused on surface MHWs, but less is known about their subsurface extent. This study uses satellite and in situ data to investigate MHWs in the Southwest Indian Ocean (SWIO). We find that MHWs in the SWIO are typically moderate in severity, closely linked to mesoscale eddies, and that strong temperature anomalies extend below surface-identified MHWs.
Arachaporn Anutaliya
Ocean Sci., 19, 335–350, https://doi.org/10.5194/os-19-335-2023, https://doi.org/10.5194/os-19-335-2023, 2023
Short summary
Short summary
To understand the circulation pattern in the Gulf of Thailand (GoT) and the local wind effect, satellite and in situ observations are used. The flow is highly variable at the western boundary and the GoT mouth. Seasonally, it is dominated by the monsoon winds and sea surface level set up by local wind rotation. Surprisingly, interannual variation in the current over each region in the GoT responds to different climate modes (El Niño–Southern Oscillation and the Indian Ocean Dipole) differently.
Svein Østerhus, Rebecca Woodgate, Héðinn Valdimarsson, Bill Turrell, Laura de Steur, Detlef Quadfasel, Steffen M. Olsen, Martin Moritz, Craig M. Lee, Karin Margretha H. Larsen, Steingrímur Jónsson, Clare Johnson, Kerstin Jochumsen, Bogi Hansen, Beth Curry, Stuart Cunningham, and Barbara Berx
Ocean Sci., 15, 379–399, https://doi.org/10.5194/os-15-379-2019, https://doi.org/10.5194/os-15-379-2019, 2019
Short summary
Short summary
Two decades of observations of the Arctic Mediterranean (AM) exchanges show that the exchanges have been stable in terms of volume transport during a period when many other components of the global climate system have changed. The total AM import is found to be 9.1 Sv and has a seasonal variation in amplitude close to 1 Sv, and maximum import in October. Roughly one-third of the imported water leaves the AM as surface outflow.
Adrienne J. Sutton, Richard A. Feely, Stacy Maenner-Jones, Sylvia Musielwicz, John Osborne, Colin Dietrich, Natalie Monacci, Jessica Cross, Randy Bott, Alex Kozyr, Andreas J. Andersson, Nicholas R. Bates, Wei-Jun Cai, Meghan F. Cronin, Eric H. De Carlo, Burke Hales, Stephan D. Howden, Charity M. Lee, Derek P. Manzello, Michael J. McPhaden, Melissa Meléndez, John B. Mickett, Jan A. Newton, Scott E. Noakes, Jae Hoon Noh, Solveig R. Olafsdottir, Joseph E. Salisbury, Uwe Send, Thomas W. Trull, Douglas C. Vandemark, and Robert A. Weller
Earth Syst. Sci. Data, 11, 421–439, https://doi.org/10.5194/essd-11-421-2019, https://doi.org/10.5194/essd-11-421-2019, 2019
Short summary
Short summary
Long-term observations are critical records for distinguishing natural cycles from climate change. We present a data set of 40 surface ocean CO2 and pH time series that suggests the time length necessary to detect a trend in seawater CO2 due to uptake of atmospheric CO2 varies from 8 years in the least variable ocean regions to 41 years in the most variable coastal regions. This data set provides a tool to evaluate natural cycles of ocean CO2, with long-term trends emerging as records lengthen.
Nathan Briggs, Kristinn Guðmundsson, Ivona Cetinić, Eric D'Asaro, Eric Rehm, Craig Lee, and Mary Jane Perry
Biogeosciences, 15, 4515–4532, https://doi.org/10.5194/bg-15-4515-2018, https://doi.org/10.5194/bg-15-4515-2018, 2018
Short summary
Short summary
We rigorously tested emerging methods for measuring the rate of photosynthesis in the ocean using autonomous robotic platforms. We found similar accuracy to traditional, labor-intensive, ship-based measurements across a variety of ocean conditions. Photosynthesis is the basis of nearly all life, both on land and in the ocean. Our results suggest that by scaling up existing technologies, we can greatly improve global monitoring of one of life's key processes.
Adrienne J. Sutton, Christopher L. Sabine, Richard A. Feely, Wei-Jun Cai, Meghan F. Cronin, Michael J. McPhaden, Julio M. Morell, Jan A. Newton, Jae-Hoon Noh, Sólveig R. Ólafsdóttir, Joseph E. Salisbury, Uwe Send, Douglas C. Vandemark, and Robert A. Weller
Biogeosciences, 13, 5065–5083, https://doi.org/10.5194/bg-13-5065-2016, https://doi.org/10.5194/bg-13-5065-2016, 2016
Short summary
Short summary
Ocean carbonate observations from surface buoys reveal that marine life is currently exposed to conditions outside preindustrial bounds at 12 study locations around the world. Seasonal conditions in the California Current Ecosystem and Gulf of Maine also exceed thresholds that may impact shellfish larvae. High-resolution observations place long-term change in the context of large natural variability: a necessary step to understand ocean acidification impacts under real-world conditions.
Andrew Delman, Janet Sprintall, Julie McClean, and Lynne Talley
Ocean Sci. Discuss., https://doi.org/10.5194/os-2016-1, https://doi.org/10.5194/os-2016-1, 2016
Revised manuscript not accepted
Short summary
Short summary
Eastward-propagating Kelvin waves are important to the development of coupled climate modes such as El Niño and the Indian Ocean Dipole. The new decomposition method presented isolates the waves' signal from sea surface height variations. The Kelvin waves are tracked effectively even when superimposed with westward-propagating waves of higher amplitude in a noisy field. When applied to satellite data, the decomposition of eastward- and westward-propagating signals is consistent with theory.
P. G. Posey, E. J. Metzger, A. J. Wallcraft, D. A. Hebert, R. A. Allard, O. M. Smedstad, M. W. Phelps, F. Fetterer, J. S. Stewart, W. N. Meier, and S. R. Helfrich
The Cryosphere, 9, 1735–1745, https://doi.org/10.5194/tc-9-1735-2015, https://doi.org/10.5194/tc-9-1735-2015, 2015
Short summary
Short summary
This study presents the improvement in the US Navy's operational sea ice forecast systems gained by assimilating high horizontal resolution satellite-derived ice concentration products. A method of blending ice concentration observations from AMSR2 along with a sea ice mask has been developed, resulting in an ice concentration product with high spatial resolution. A significant improvement in the ice edge location has been shown in the operational system assimilating this new product.
I. Cetinić, M. J. Perry, E. D'Asaro, N. Briggs, N. Poulton, M. E. Sieracki, and C. M. Lee
Biogeosciences, 12, 2179–2194, https://doi.org/10.5194/bg-12-2179-2015, https://doi.org/10.5194/bg-12-2179-2015, 2015
Short summary
Short summary
The ratio of simple optical properties measured from underwater autonomous platforms, such as floats and gliders, is used as a new tool for studying phytoplankton distribution in the North Atlantic Ocean. The resolution that optical instruments carried by autonomous platforms provide allows us to study phytoplankton patchiness and its drivers in the oceanic systems.
M. Lankhorst, G. Chavez, S. H. Nam, and U. Send
Ocean Sci. Discuss., https://doi.org/10.5194/osd-11-2447-2014, https://doi.org/10.5194/osd-11-2447-2014, 2014
Revised manuscript has not been submitted
Cited articles
Argo: Argo float data and metadata from Global Data Assembly Centre (Argo GDAC), https://doi.org/10.17882/42182, 2000.
Boyer, T. P., Antonov, J. I., Baranova, O. K., Coleman, C., Garcia, H. E., Grodsky, A., Johnson, D. R., Locarnini, R. A., Mishonov, A. V., O'Brien, T. D., Paver, C. R., Reagan, J. R., Seidov, D., Smolyar, I. V., and Zweng, M. M.: World Ocean Database 2013, NOAA Atlas NESDIS 72, edited by: Levitus, S. and Mishonov, A., Silver Spring, MD, 209 pp., https://doi.org/10.7289/V5NZ85MT, 2013.
Delman, S. A., McClean, J. L., Sprintall, J., Talley, L. D., Yulaeva, E., and Jayne, S. R.: Effects of Eddy Vorticity Forcing on the Mean State of the Kuroshio Extension, J. Phys. Oceanogr., 45, 1356–1375, 2015.
de Vos, A., Pattiaratchi, C. B., and Wijeratne, E. M. S.: Surface circulation and upwelling patterns around Sri Lanka, Biogeosciences, 11, 5909–5930, https://doi.org/10.5194/bg-11-5909-2014, 2014
Ducet, N., Traon, P. Y. L., and Reverdin, G.: Global high-resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and -2, J. Geophys. Res., 105, 19477–19498, 2000.
Durand, F., Shankar, D., Birol, F., and Shenoi, S. S. C.: Spatiotemporal structure of the East India Coastal Current from satellite altimetry. J. Geophys. Res., 114, C02013, https://doi.org/10.1029/2008JC004807, 2009.
Eigenheer, A. and Quadfasel, D.: Seasonal variability of the Bay of Bengal circulation inferred from TOPEX/Poseidon altimetry, J. Geophys. Res., 105, 3243–3252, https://doi.org/10.1029/1999JC900291, 2000.
Gordon, A. L., Shroyer, E. L., Mahadevan, A., Sengupta, D., and Freilich, M.: Bay of Bengal: 2013 northeast monsoon upper-ocean circulation, Oceanography, 29, 82–91, https://doi.org/10.5670/oceanog.2016.41, 2016.
Hacker, P., Firing, E., and Hummon, J.: Bay of Bengal currents during the northeast monsoon, Geophys. Res. Lett., 25, 2769–2772, https://doi.org/10.1029/98GL52115, 1998.
Jensen, T. G., Wijesekera, H. W., Nyadjro, E. S., Thoppil, P. G., Shriver, J. F., Sandeep, K. K., and Pant, V.: Modeling salinity exchanges between the equatorial Indian Ocean and the Bay of Bengal, Oceanography, 29, 92–101, https://doi.org/10.5670/oceanog.2016.42, 2016.
Killworth, P. D. and Blundell, J. R.: Long extratropical planetary wave propagation in the presence of slowly varying mean flow and bottom topography, Part I: The local problem, J. Phys. Oceanogr., 33, 784–801, 2003.
Lee, C. M., Jinadasa, S. U. P., Anutaliya, A., Centurioni, L. R., Fernando, H. J. S., Hormann, V., Lankhorst, M., Rainville, L., Send, U., and Wijesekera, H. W.: Collaborative observations of boundary currents, water mass variability, and monsoon response in the southern Bay of Bengal, Oceanography, 29, 102–111, https://doi.org/10.5670/oceanog.2016.43, 2016.
Luyten, J. R. and Roemmick, D. H.: Equatorial currents at semiannual period in the Indian Ocean, J. Phys. Oceanogr., 12, 406–413, 1982.
Maltrud, M. E., Bryan, F. O., and Peacock, S.: Boundary impulse response functions in a century-long eddying global ocean simulation, Environ. Fluid Mech., 10, 275–295, https://doi.org/10.1007/s10652-009-9154-3, 2010.
McCreary, J. P., Han, W., Shankar, D., and Shetye, S. R.: Dynamics of the East India Coastal Current 2. Numerical solutions, J. Geophys. Res., 101, 13993–14010, https://doi.org/10.1029/96JC00560, 1996.
Metzger, E. J., Hurlburt, H. E., Xu, X., Shriver, J. F., Gordon, A. L., Sprintall, J., Susanto, R. D., and van Aken, H. M.: Simulated and observed circulation in the Indonesian Seas: 1/12° global HYCOM and the INSTANT observations, Dynam. Atmos. Oceans, 50, 275–300, https://doi.org/10.1016/j.dynatmoce.2010.04.002, 2010.
Mukherjee, A., Shankar, D., Fernando, V., Amol, P., Aparna, S. G., Fernandes, R., Michael, G. S., Khalap, S. T., Satelkar, N. P., Agarvadekar, Y., Gaonkar, M. G., Tari, A. P., Kankonkar, A., and Vernekar, S.: Observed seasonal and intraseasonal variability of the East India Coastal Current on the continental slope, J. Earth Syst. Sci., 123, 1197–1232, https://doi.org/10.1007/s12040-014-0471-7, 2014.
Rao, R. R. and Sivakumar, R.: Seasonal variability of sea surface salinity and salt budget of the mixed layer of the north Indian Ocean, J. Geophys. Res.-Oceans, 108, 9-1–9-14, https://doi.org/10.1029/2001JC000907, 2003.
Reppin, J., Schott, F. A., and Fischer, J.: Equatorial currents and transports in the upper central Indian Ocean: Annual cycle and interannual variability, J. Geophys. Res., 104, 15495–15514, 1999.
Rosmond, T. E., Teixeira, J., Peng, M., Hogan, T. F., and Pauley, R.: Navy Operational Global Atmospheric Prediction System (NOGAPS): forcing for ocean models, Oceanography, 15, 99–108, 2002.
Schott, F. A., Reppin, J., and Fischer, J.: Currents and transports of the Monsoon Current south of Sri Lanka, J. Geophys. Res., 99, 25127–25141, 1994.
Sengupta, D., Bhsrath Raj, G. N., and Shenoi, S. S. C.: Surface freshwater from Bay of Bengal runoff and Indonesian Throughflow in the tropical Indian Ocean, Geophys. Res. Lett., 33, L22609, https://doi.org/10.1029/2006GL027573, 2006.
Shankar, D., McCreary, J. P., and Han, W.: Dynamics of the East India Coastal Current 1. Analytic solutions forced by interior Ekman pumping and local alongshore winds, J. Geophys. Res., 101, 13975–13991, 1996.
Shankar, D., Vinayachandran, P. N., and Unnikrishnan, A. S.: The monsoon currents in the north Indian Ocean, Prog. Oceanogr., 52, 63–120, https://doi.org/10.1016/S0079-6611(02)00024-1, 2002.
Shetye, S. R., Gouveia, A. D., Shenoi, S. S. C., Sundar, D., Michael, G. S., and Nampoothiri, G.: The western boundary current of the seasonal subtropical gyre in the Bay of Bengal, J. Geophys. Res., 98, 945–954, 1993.
Shetye, S. R., Gouveia, A. D., Shankar, D., Shenoi, S. S. C., Vinayachandran, P. N., Sundar, D., Michael, G. S., and Nampoothiri, G.: Hydrography and circulation in the western Bay of Bengal during the northeast monsoon, J. Geophys. Res., 101, 14011–14025, 1996.
Smith, R., Jones, P., Briegleb, B., Bryan, F., Danabasoglu, G., Dennis, J., Dukowicz, J., Eden, C., Fox-Kemper, B., Gent, P., Hecht, M., Jayne, S., Jochum, M., Large, W., Linday, K., Maltrud, M., Norton, N., Peacock, S., Vertenstein, M., and Yeager, S.: The Parallel Ocean Program (POP) reference manual, LANL/NCAR Tech. Rep. LAUR-10-01853, 140 pp., 2010.
Vinayachandran, P. N. and Yamagata, T.: Monsoon response of the sea around Sri Lanka: generation of thermal domes and anticyclonic vortices, J. Phys. Oceanogr., 28, 1946–1960, 1997.
Vinayachandran, P. N., Masumoto, Y., Mikawa, T., and Yamagata, T.: Intrusion of the southwest monsoon current into the Bay of Bengal, J. Geophys. Res., 104, 11077–11085, 1999.
Vinayachandran, P. N., Shankar, D., Vernekar, S., Sandeep, K. K., Amol, P., Neema, C. P., and Chatterjee, A.: A summer monsoon pump to keep the Bay of Bengal salty, Geophys. Res. Lett., 40, 1777–1782, https://doi.org/10.1002/grl.50274, 2013.
Wijesekera, H. W., Jensen, T. G., Jarosz, E., Teague, W. J., Metzger, E. J., Wang, D. W., Jinadasa, S. U. P., Arulananthan, K., Centurioni, L. R., and Fernando, H. J. S.: Southern Bay of Bengal currents and salinity intrusions during the northeast monsoon, J. Geophys. Res.-Oceans, 120, 6897–6913, https://doi.org/10.1002/2015JC010744, 2015.
Wijesekera, H. W., Teague, W. J., Jarosz, E., Wang, D. W., Jensen, T. G., Jinadasa, S. U. P., Fernando, H. J. S., Centurioni, L. R., Hallock, Z. R., Shroyer, E. L., and Moum, J. N.: Observations of currents over the deep southern Bay of Bengal – With a little luck, Oceanography, 29, 112–123, https://doi.org/10.5670/oceanog.2016.44, 2016a.
Wijesekera, H. W., Teague, W. J., Wang, D. W., Jarosz, E., and Jensen, T. G.: Low-Frequency Currents from Deep Moorings in the Southern Bay of Bengal, J. Phys. Oceanogr., 46, 3209–3238, https://doi.org/10.1175/JPO-D-16-0113.1, 2016b.
Wilson, E. A. and Riser, S. C.: An Assessment of the Seasonal Salinity Budget for the Upper Bay of Bengal, J. Phys. Oceanogr., 46, 1361–1376, 2016.
Wyrtki, K.: An Equatorial Jet in the Indian Ocean, Science, 181, 262–264, 1973.
Yu, L., O'Brien, J. J., and Yang, J.: On the Remote Forcing of the Circulation in the Bay of Bengal, J. Geophys. Res., 96, 20449–20454, 1991.
Short summary
Observations and numerical models reveal the existence of the subsurface current in the opposite direction to the surface current off the Sri Lankan east coast. The undercurrent (200–1000 m layer) is most pronounced during the boreal spring and summer and transports more mass than the surface layer (0–200 m). Although the undercurrent is potentially a pathway of salt exchange between the Arabian Sea and the Bay of Bengal, the data and models suggest little salt transport by the undercurrent.
Observations and numerical models reveal the existence of the subsurface current in the opposite...
