Open Journal Systems

The annual cycle of surface eddy kinetic energy and its influence on eddy momentum fluxes as inferred from altimeter data

Xiaoming Zhai

Article ID: 299
Vol 2, Issue 2, 2017, Article identifier:

VIEWS - 670 (Abstract) 470 (PDF)

Abstract

The annual cycle of surface eddy kinetic energy (EKE) and its influence on eddy momentum fluxes are investigated using an updated record of satellite altimeter data. It is found that there is a phase difference between the annual cycles of EKE in the western boundary current regions and EKE in the interior of the subtropical gyres, suggesting that different mechanisms may be at work in different parts of the subtropical gyres. The annual cycles of EKE averaged in the two hemispheres are found to be of similar magnitude but in opposite phase. As a result, the globally-averaged EKE shows little seasonal variability. The longer record of altimeter data used in this study has brought out a clearer and simpler picture of eddy momentum fluxes in the Gulf Stream and Kuroshio Extension. Considerable seasonal variations in eddy momentum fluxes are found in the western boundary current regions, which potentially play an important role in modulating the strength of the western boundary currents and their associated recirculation gyres on the seasonal time scale.

Keywords

eddy kinetic energy; eddy momentum flux; seasonal cycle; western boundary current; altimeter

Full Text:

PDF

References

Ducet N and Le Traon P-Y. (2001). A comparison of surface eddy kinetic energy and Reynolds stresses in the Gulf Stream and the Kuroshio Current systems from merged TOPEX/Poseidon and ERS-1/2 altimetric data. J Geophys Res Lett, 106(C8): 16603–16622. http://dx.doi.org/10.1029/2000JC000205

Duhaut T H A and Straub D N. (2006). Wind stress dependence on ocean surface velocity: Implications for mechanical energy input to ocean circulation. J Phys Oceanogr, 36: 202–211. http://dx.doi.org/10.1175/JPO2842.1

Eady E T. (1949). Long waves and cyclone waves. Tellus, 1(3): 33–52. http://dx.doi.org/10.1111/j.2153-3490.1949.tb01265.x

Greatbatch R J, Zhai X, Kohlmann J-D, et al. (2010a). Ocean eddy momentum fluxes at the latitudes of the Gulf Stream and the Kuroshio extensions as revealed by satellite data. Ocean Dyn, 60(3): 617–628. http://dx.doi.org/10.1007/s10236-010-0282-6

Greatbatch R J, Zhai X, Claus M, et al. (2010b). Transport driven by eddy momentum fluxes in the Gulf Stream Extension region. Geophys Res Lett, 37(24): L24401. http://dx.doi.org/10.1029/2010GL045473

Hecht M W and Smith R D. (2008). Towards a physical understanding of the North Atlantic: A review of model studies in an eddying regime. In: Hecht M W and Hasumi H (editors). Ocean modelling in an eddying regime. Washington: American Geophysical Union, p.213–240. http://dx.doi.org/10.1029/GM177

Morrow R A, Coleman R, Church J, et al. (1994). Surface eddy momentum flux and velocity variances in the Southern Ocean from GEOSAT altimetry. J Phys Oceanogr, 24: 2050–2071. http://dx.doi.org/10.1175/1520-0485(1994)024<2050:SEMFAV>2.0.CO;2

Niiler P P, Maximenko N A and McWilliams J C. (2003). Dynamically balanced absolute sea level of the global ocean derived from near-surface velocity observations. Geophys Res Lett, 30(22): 2164. http://dx.doi.org/10.1029/2003GL018628

Penduff T, Barnier B, Dewar W K, et al. (2004). Dynamical responses of the oceanic eddy field to the North Atlantic Oscillation: A model-data comparison. J Phys Oceanogr, 34: 2615–2629. http://dx.doi.org/10.1175/JPO2618.1

Qiu B. (1999). Seasonal eddy field modulation of the North Pacific Subtropical Countercurrent: TOPEX/Poseidon observations and theory. J Phys Oceanogr, 29: 2471–2486. http://dx.doi.org/10.1175/1520-0485(1999)029<2471:SEFMOT>2.0.CO;2

Qiu B, Chen S, Hacker P, et al. (2008). The Kuroshio Extension northern recirculation gyre: Profiling float measurements and forcing mechanism. J Phys Oceanogr, 38: 1764–1779. http://dx.doi.org/10.1175/2008JPO3921.1

Rieck J K, Böning C W, Greatbatch R J, et al. (2015). Seasonal variability of eddy kinetic energy in a global high-resolution ocean model. Geophys Res Lett, 42(21): 9379–9386. http://dx.doi.org/10.1002/2015GL066152

Scott R B, Arbic B K, Holland C L, et al. (2008). Zonal versus meridional velocity variance in satellite observations and realistic and idealised ocean circulation models. Ocean Modell, 23(3–4): 102–112. http://dx.doi.org/10.1016/j.ocemod.2008.04.009

Stammer D and Wunsch C. (1999). Temporal changes in eddy energy of the ocean. Deep Sea Res, 46(1–2): 77–108. http://dx.doi.org/10.1016/S0967-0645(98)00106-4

Wilson C, Hughes C, and Blundell J R. (2015). Forced and intrinsic variability in the response to increased wind stress of an idealised Southern Ocean. J Geophys Res, 120(1): 113–130. http://dx.doi.org/10.1002/2014JC010315

Xu C, Zhai X and Shang X D. (2016). Work done by atmospheric winds on mesoscale ocean eddies. Geophys Res Lett, 43(23): 12,174–12,180. http://dx.doi.org/10.1002/2016GL071275

Zhai X and Greatbatch R J. (2006a). Surface eddy diffusivity for heat in a model of the northwest Atlantic Ocean. Geophys Res Lett, 33(24): L24611. http://dx.doi.org/10.1029/2006GL028712

Zhai X and Greatbatch R J. (2006b). Inferring eddy-induced diffusivity for heat in the surface mixed layer using satellite data. Geophys Res Lett, 33(24): L24607. http://dx.doi.org/10.1029/2006GL027875

Zhai X and Greatbatch R J. (2007). Wind work in a model of the northwest Atlantic Ocean. Geophys Res Lett, 34(4): L04606. http://dx.doi.org/10.1029/2006GL028907

Zhai X and Wunsch C. (2013). On the variability of wind power input to the oceans with a focus on the subpolar North Atlantic. J Clim, 26: 3892–3903. http://dx.doi.org/10.1175/JCLI-D-12-00472.1

Zhai X, Greatbatch R J and Sheng J. (2004). Diagnosing the role of eddies in driving the circulation of the northwest Atlantic Ocean. Geophys Res Lett, 31(23): L23304. http://dx.doi.org/10.1029/2004GL021146

Zhai X, Greatbatch R J and Kohlmann J-D. (2008). On the seasonal variability of eddy kinetic energy in the Gulf Stream region. Geophys Res Lett, 35(24): L24609. http://dx.doi.org/10.1029/2008GL036412


DOI: http://dx.doi.org/10.18063/som.v2i2.299
(670 Abstract Views, 470 PDF Downloads)

Refbacks

  • There are currently no refbacks.


Copyright (c) 2017 Satellite Oceanography and Meteorology