Skip to content

Research Topics

Western boundary currents, their extensions, and mode waters

Ocean circulation and water mass properties in the western boundary currents and their extensions (WBCs), e.g. the Gulf Stream and Kuroshio-Oyashio Extensions, exhibit strong variability at interannual to multi-decadal time scale. In addition, WBCs involve strong ocean-atmosphere exchanges of heat, momentum, and fresh water, indicating key roles in the climate system. For example, the largest the net surface heat flux over the global ocean is found in WBCs, in terms of mean values as well as the variance at time scales longer than a few years. Focus of my research is on how WBCs and their mode waters respond to stochastic atmospheric forcing to generate the decadal variability, and what are the pathways through which the atmospheric forcing reaches the WBCs.

Selected related publications:

Kwon, Y.-O., and S.C. Riser, 2004:  North Atlantic Subtropical Mode Water:  A history of ocean-atmosphere interaction 1961-2000.  Geophys. Res. Lett., 31, L19307, doi:10.1029/2004GL021116. [pdf]

Kwon, Y.-O., and C. Deser, 2007:  North Pacific decadal variability in Community Climate System Model Version 2.  J. Climate, 20, 2416–2433. [pdf]

Andres, M., Y.-O. Kwon, and J. Yang., 2011: Observations of the Kuroshio’s barotropic and baroclinic responses to basin-wide wind forcing, J. Geophys. Res., 116, C04011, doi:10.1029/2010JC006863. [pdf]

Kwon, Y.-O., J.J. Park, S.F. Gary*, and M.S. Lozier, 2015: Year-to-year re-outcropping of Eighteen Degree Water in an eddy-resolving ocean simulation. J. Phys. Oceanogr., 45, 1189-1204. doi: [pdf]

Ocean-to-atmosphere feedback and decadal climate variability

The ocean-to-atmosphere feedback is a key, but relatively poorly-understood aspect of the ocean’s role in climate variability, particularly in mid-latitudes. Observations show that the ocean and atmosphere in the extra-tropics exhibit variability on multi-year time scales, such as in the Pacific Decadal Oscillation (PDO) and the North Atlantic Oscillation (NAO). The ocean has long been thought to be the source of such long time scales, since the atmosphere has practically no memory from one year to the next. However, there is currently very little consensus on how or actually whether the long-time-scale ocean variability impacts the atmospheric circulation outside of the tropics. My research focuses on the how the atmosphere responds to the strong decadal variability in WBCs.

Selected related publications:

Kwon, Y.-O., and C. Deser, 2007:  North Pacific decadal variability in Community Climate System Model Version 2.  J. Climate, 20, 2416–2433. [pdf]

Kwon, Y.-O., M.A. Alexander, N.A. Bond, C. Frankignoul, H. Nakamura, B. Qiu, L. Thompson, 2010: Role of Gulf Stream and Kuroshio-Oyashio Systems in Large-Scale Atmosphere-Ocean Interaction: A Review. J. Climate, 23, 3249–3281. [pdf]

Kwon, Y.-O., and T.M. Joyce, 2013: Northern Hemisphere Winter Atmospheric Transient Eddy Heat Fluxes and the Gulf Stream and Kuroshio-Oyashio Extension Variability. J. Climate, 26, 9839-9859, doi:10.1175/JCLI-D-12-00647.1. [pdf]

Smirnov, D., M. Newman, M.A. Alexander, Y.-O. Kwon, and C. Frankignoul, 2015: Investigating the local atmospheric response to a realistic shift in the Oyashio sea surface temperature front. J. Climate, 28, 1126-1147. doi: [pdf]

Atlantic meridional overturning circulation and meridional heat transport

The Atlantic Meridional Overturning Circulation (AMOC) is another particular example, in which extra-tropical ocean dynamics play a crucial role in shaping the pronounced decadal variability. The AMOC is a crucial component of the Atlantic as well as the global climate, for example through its close relationship with the meridional ocean heat transport and the Atlantic Multidecadal Oscillation. My research interest is in decadal variability of the AMOC, in particular the role of WBC’s in AMOC variability, and the associated climate impacts.

Selected related publications:

Kwon, Y.-O., and C. Frankignoul, 2012: Stochastically-Driven multi-decadal variability of the Atlantic meridional overturning circulation in CCSM3. Climate Dyn., 38, 895-876, doi:10.1007/s00382-011-1040-2. [pdf]

Danabasoglu, G., S.G. Yeager, Y.-O. Kwon, J.J. Tribbia, A.S. Phillips, and J. Hurrell, 2012: Variability of the Atlantic Meridional Overturning Circulation in CCSM4. J. Climate, 25, 5153-5172, doi:10.1175/JCLI-D-11-00595.1. [pdf]

Kwon, Y.-O., and C. Frankignoul, 2014: Mechanisms of Multidecadal Atlantic Meridional Overturning Circulation Variability Diagnosed in Depth versus Density Space. J. Climate, 27, 9359-9376. doi: [pdf]

Frankignoul, C., G. Gastineau, and Y.-O. Kwon, 2015: Wintertime atmospheric response to North Atlantic ocean circulation variability in a climate model.  J. Climate, 28, 7659-7677, doi: [pdf]

Impact of basin-scale climate variability on the coastal environment and ecosystem

I have recently become interested in the physical and biological mechanistic links between the North Atlantic basin-scale climate variability, e.g. Gulf Stream, NAO and AMOC variability, and the coastal environment and ecosystem changes on the U.S. and Canadian shelf in collaboration with the fisheries scientist and coastal oceanographers.

Selected related publications:

Nye, J.A., T.M. Joyce, Y.-O. Kwon, and J.S. Link, 2011: Gulf Stream position determines spatial distribution of silver hake. Nature Commun., 2:412, doi:10.1038/ncomms1420. [pdf]

Chen, K.*, G. Gawarkiewicz, Y.-O. Kwon, and W. G. Zhang, 2015: Role of atmospheric forcing versus ocean advection during the anomalous warming on the Northeast U.S. shelf in 2012, J. Geophys. Res.120, 4324–4339, doi:10.1002/2014JC010547. [pdf]

Richaud, B.*, Y.-O. Kwon, T.M. Joyce, P.S. Fratantoni, and S.J. Lentz, 2016: Surface and bottom temperature and salinity climatology along the continental shelf off the Canadian and U.S. East Coasts. Cont. Shelf Res., 124, 165-181, doi:10.1016/j.csr.2016.06.005. [pdf]

Davis, X. J.*, T.M. Joyce, and Y.-O. Kwon, 2017: Prediction of silver hake distribution on the Northeast U.S. shelf based on the Gulf Stream path index. Cont. Shelf Res., 138, 51-64, doi:10.1016/j.csr.2017.03.003. [pdf]