My research interests focus on understanding the mechanisms governing global atmosphere-ocean dynamics and their impacts on climate variability. I use both observations and mathematical models, such as general atmosphere-ocean circulation models, as my research tools. Currently, my research lies in the areas of inter-basin ocean transports of heat, salt and carbon; atmosphere-ocean processes conducive to extreme weather events; Antarctic sea-ice variability; and inter-ENSO variability.
Contrasting sea-ice trends around West Antarctica: Since late 1978, Antarctic sea-ice extent has overall expanded in all seasons in stark contrast to the retreating Arctic sea-ice extent. However, while the sea-ice extent around East Antarctica has increased monotonically, the sea-ice around West Antarctica exhibits regionally and seasonally inhomogeneous trends. For instance, Antarctic sea-ice extent in the East Pacific has decreased substantially in Austral summer. We used an ocean and sea-ice coupled model to show that the increased wind-driven upwelling of the relatively warm subsurface water, known as upper Circumpolar Deep Water, is mainly responsible for the declining sea-ice extent. This study also explains how the changes in Weddell Gyre circulations and associated meridional heat transport contributed to the increasing Antarctic sea ice in the Atlantic during Austral summer (Lee et al. 2017) [JGR editor's highlight].
Abrupt increase in Indian Ocean heat content during the warming hiatus: Global mean surface warming has stalled since the end of the 20th century, but the net radiation imbalance at the top of the atmosphere continues to suggest an increasingly warming planet. This apparent contradiction has been reconciled by an anomalous heat flux into the Pacific Ocean, induced by a shift toward a La Nina-like state over the past decade or so. This study found that the enhanced heat uptake by the Pacific Ocean has been compensated by an increased heat transport from the Pacific Ocean to the Indian Ocean, carried by the Indonesian throughflow. As a result, Indian Ocean heat content has increased abruptly during the warming hiatus (Lee et al. 2015) [highlighted in EOS and Nature].
Spring persistence, transition and resurgence of El Nino: An objective method is presented to explore the differences in the space-time evolution of equatorial Pacific SST anomalies observed during El Nino events. This inter-El Nino variability is captured by two leading orthogonal modes, which explain more than 60% of the interevent variance. The first mode illustrates the extent to which warm SST anomalies in the eastern tropical Pacific persist into the boreal spring after the peak of El Nino. The second mode captures the transition and resurgence of El Nino in the following year (Lee et al. 2014).
What drives the southern subtropical anticyclones in austral winter?: The southern subtropical anticyclones are notably stronger in austral winter than in summer, which is in contrast with the Northern Hemisphere in which subtropical anticyclones are more intense in boreal summer consistent with the monsoon heating paradigm. Specially designed model experiments show that during boreal summer enhanced tropical convection activity in the Northern Hemisphere plays important roles in strengthening the southern subtropical anticyclones (Lee et al. 2013).
An optimal ENSO phase for U.S. tornado outbreaks: Among the top ten extreme U.S. tornado outbreak years during 1950-2010, seven years including the top three are identified with a strongly positive Trans-Niño phase. Modeling experiments suggest that a positive Trans-Niño phase provides large-scale atmospheric conditions conducive to intense tornado outbreaks over the U.S. (Lee et al. 2013) [highlighted in Bulletin of the American Meteorological Society as Paper in Note].
What caused the significant increase in Atlantic ocean heat content since the mid-20th century?: As the upper layer of the world ocean warms gradually during the 20th century, the inter-ocean heat transport from the Indian to Atlantic basin should be enhanced, and the Atlantic Ocean should therefore gain extra heat due to the increased upper ocean temperature of the inflow via the Agulhas leakage. Consistent with this hypothesis, instrumental records indicate that the Atlantic Ocean has warmed substantially more than any other ocean basin since the mid-20th century. A surface-forced global ocean-sea ice coupled model is used to confirm this hypothesis (Lee et al. 2011) [highlighted in Nature as Community Choice].
Delayed advective oscillation of the AMOC: A simple dynamic model is proposed to illustrate the multidecadal oscillation of the AMOC. The proposed oscillation relies on alternating actions of positive and negative feedbacks, which are operated by a slow adjustment of the ocean circulation and the associated time delay in the advective flux response to meridional density gradient perturbation (Lee and Wang 2010).
Work in progress
Lee, S.-K., M. Goes, H. Lopez, A. Gronholz, and S. Dong: Southward pathways of the upper and lower North Atlantic Deep Water and their impact on the Atlantic meridional heat transport, In preparation.
Dong, J., R. Domingues, G. Goni, G. Halliwell, H. Kim, S.-K. Lee, M. Mehari, F. Bringas, J. Morell, and L. Pomales, 2017: Impact of assimilating underwater glider data on Hurricane Gonzalo (2014) forecast. Wea. Forecasting., 32, 1143-1159, doi:10.1175/WAF-D-16-0182.1.
Lee, S.-K., D. Volkov, H. Lopez, W. G. Cheon, A. L. Gordon, Y. Liu, and R. Wanninkhof, 2017: Wind-driven ocean dynamics impact on the contrasting sea-ice trends around West Antarctica. J. Geophys. Res. Oceans, 122, 4413-4430, doi:10.1002/2016JC012416.
Muhling, B. A., R. Brill, J. T. Lamkin, M. A. Roffer, S.-K. Lee, Y. Liu, and F. Muller-Karger, 2017: Projections of future habitat use by Atlantic bluefin tuna: mechanistic vs. correlative distribution models. ICES J. Mar. Sci., 74, 698-716, doi:10.1093/icesjms/fsw215.
Volkov, D., S.-K. Lee, F. Landerer, and R. Lumpkin, 2017: Decade-long deep-ocean warming detected in the subtropical South Pacific. Geophys. Res. Lett., 44, 927-936, doi:10.1002/2016GL071661.
Lee, S.-K., A. T. Wittenberg, D. B. Enfield, S. J. Weaver, C. Wang and R. Atlas, 2016: U.S. regional tornado outbreaks and their links to ENSO flavors and North Atlantic SST variability. Environ. Res. Lett., 11, 044008, doi:10.1088/1748-9326/11/4/044008.
Lopez, H., S. Dong, S.-K. Lee and G. Goni, 2016: Decadal modulations of interhemispheric global atmospheric circulations and monsoons by the South Atlantic Meridional Overturning Circulation. J. Climate, 29, 1831-1851, doi:http://dx.doi.org/10.1175/JCLI-D-15-0491.1.
Lopez, H., S. Dong, S.-K. Lee and E. Campos, 2016: Remote influence of Interdecadal Pacific Oscillation on the South Atlantic Meridional Overturning Circulation variability. Geophys. Res. Lett., 43, 8250-8258, doi:10.1002/2016GL069067.
Cheon, W. G., S.-K. Lee, A. L. Gordon, Y. Liu, C.-B. Cho and J. Park, 2015: Replicating the 1970s' Weddell Polynya using a coupled ocean - sea ice model with reanalysis surface flux fields. Geophys. Res. Lett., 42, 5411-5418, doi:10.1002/2015GL064364.
Domingues, R., G. Goni, F. Bringas, S.-K. Lee, H.-S. Kim, G. Halliwell, J. Dong, J. Morell and L. Pomales, 2015: Upper-ocean response to Hurricane Gonzalo (2014): salinity effects revealed by sustained and targeted observations from underwater gliders. Geophys. Res. Lett., 42, 7131-7138, doi:10.1002/2015GL065378.
Jo, H.-S., S.-W. Yeh and S.-K. Lee, 2015: Changes in the relationship in the SST variability between the tropical Pacific and the North Pacific across the 1998/99 regime shift. Geophys. Res. Lett., 42, 7171-7178, doi:10.1002/2015GL065049.
Lee, S.-K., W. Park, M. O. Baringer, A. L. Gordon, B. Huber and Y. Liu, 2015: Pacific origin of the abrupt increase in Indian Ocean heat content during the warming hiatus. Nature Geosci., 8, 445-449, doi:10.1038/ngeo2438.
Liu, H., C. Wang, S.-K. Lee and D. Enfield, 2015: Inhomogeneous influence of the Atlantic Warm Pool on United States precipitation. Atmosph. Sci. Lett., 16, 6369, doi: 10.1002/asl2.521.
Liu, Y., S.-K. Lee, D. B. Enfield, B. A. Muhling, J. T. Lamkin, F. Muller-Karger and M. A. Roffer, 2015: Potential impact of climate change on the Intra-Americas Seas: Part-1. A dynamic downscaling of the CMIP5 model projections. J. Marine Syst., 148, 56-69, doi:10.1016/j.jmarsys.2015.01.007.
Muhling B. A., Y. Liu, S.-K. Lee, J. T. Lamkin, M. A. Roffer, F. Muller-Karger and J. F. Walter, 2015: Potential impact of climate change on the Intra-Americas Seas: Part-2. Implications for Atlantic bluefin tuna and skipjack tuna adult and larval habitats. J. Marine Syst., 148, 1-13, doi:10.1016/j.jmarsys.2015.01.010.
Song, Z. S.-K. Lee, C. Wang, B. Kirtman and F. Qiao, 2015: Contributions of the atmosphere-land and ocean-sea ice model components to the tropical Atlantic SST bias in CESM1. Ocean Modelling, 96, 280-290, doi:10.1016/j.ocemod.2015.09.008.
van Hooidonk, R., J. A. Maynard, Y. Liu and S.-K. Lee, 2015: Downscaled projections of Caribbean coral bleaching that can inform conservation planning. Glob. Change Biol., 21, 3389-3401, doi: 10.1111/gcb.12901.
Cheon, W. G., Y.-G. Park, J. R. Toggweiler and S.-K. Lee, 2014: The relationship of Weddell polynya and open-ocean deep convection to the Southern Hemisphere westerlies. J. Phys. Oceanogr., 44, 694-713, doi: http://dx.doi.org/10.1175/JPO-D-13-0112.1
Ji, X., J. D. Neelin, S.-K. Lee and C. R. Mechoso, 2014: Interhemispheric teleconnections from tropical heat sources in intermediate and simple models. J. Climate, 27, 684-697, doi: http://dx.doi.org/10.1175/JCLI-D-13-00017.1.
Lee, S.-K., P. N. DiNezio, E.-S. Chung, S.-W. Yeh, A. T. Wittenberg and C. Wang, 2014: Spring persistence, transition and resurgence of El Nino. Geophys. Res. Lett., 41, 8578-8585, doi:10.1002/2014GL062484.
Lee, S.-K., B. E. Mapes, C. Wang, D. B. Enfield and S. J. Weaver, 2014: Springtime ENSO phase evolution and its relation to rainfall in the continental U.S. Geophys. Res. Lett., 41, 1673-1680, doi:10.1002/2013GL059137.
Wang, C., L. Zhang, S.-K. Lee, L. Wu and C. R. Mechoso, 2014: A global perspective on CMIP5 climate model biases. Nature Clim. Change, 4, 201-205, doi:10.1038/nclimate2118.
Zhang, L., C. Wang and S.-K. Lee, 2014: Potential role of Atlantic warm pool-induced freshwater forcing in the Atlantic meridional overturning circulation: Ocean-sea ice coupled model simulations. Climate Dynam., 43, 553-574, doi:10.1007/s00382-013-2034-z.
Zhang, L. C. Wang, Z. Song, S.-K. Lee, 2014: Remote effect of the model cold bias in the tropical North Atlantic on the warm bias in the tropical southeastern Pacific. J. Adv. Model. Earth Syst., 6, 1016-1026, doi:10.1002/2014MS000338.
Lee, S.-K., C. R. Mechoso, C. Wang and J. D. Neelin, 2013: Interhemispheric influence of the northern summer monsoons on the southern subtropical anticyclones. J. Climate, 26, 10193-10204, doi:http://dx.doi.org/10.1175/JCLI-D-13-00106.1.
Lee, S.-K., R. Atlas, D. B. Enfield, C. Wang and H. Liu, 2013: Is there an optimal ENSO pattern that enhances large-scale atmospheric processes conducive to major tornado outbreaks in the U.S.? J. Climate, 26, 1626-1642, doi:http://dx.doi.org/10.1175/JCLI-D-12-00128.1. [highlighted in Feb, 2013 issue of Bulletin of the American Meteorological Society as Paper in Note]
Liu, H., C. Wang, S.-K. Lee and D. B. Enfield, 2013: Atlantic warm pool variability in the CMIP5 simulations. J. Climate, 26, 5315-5336, doi: http://dx.doi.org/10.1175/JCLI-D-12-00556.1.
Menary, M. B, C. D. Roberts, M. D. Palmer, P. R. Halloran, L. Jackson, R. A. Wood, W. A. Mueller, D. Matei and S.-K. Lee, 2013: Mechanisms of aerosol-forced AMOC variability in a state of the art climate model. J. Geophys. Res. Oceans, 118, 2087-2096, doi:10.1002/jgrc.20178.
Wang, C., L. Zhang, S.-K. Lee, 2013: Response of freshwater and sea surface salinity to variability of the Atlantic warm pool. J. Climate, 26, 1249-1267, doi:10.1175/JCLI-D-12-00284.1.
DiNezio, P. N., B. P. Kirtman, A. C. Clement, S.-K. Lee, G. A. Vecchi and A. Wittenberg, 2012: Mean climate controls on the simulated response of ENSO to increasing greenhouse gases. J. Climate, 25, 7399-7420, doi: http://dx.doi.org/10.1175/JCLI-D-11-00494.1.
Larson, S., S.-K. Lee, C. Wang, E.-S. Chung and D. Enfield, 2012: Impacts of non-canonical El Nino patterns on Atlantic hurricane activity. Geophys. Res. Lett., 39, L14706, doi:10.1029/2012GL052595.
Liu, H., C. Wang, S.-K. Lee and D. B. Enfield, 2012: Atlantic warm pool variability in the IPCC twentieth-century climate simulations. J. Climate, 25, 5612-5628, doi:10.1175/JCLI-D-11-00376.1.
Liu, Y., S.-K. Lee, B. A. Muhling, J. T. Lamkin and D.B. Enfield, 2012: Significant reduction of the Loop Current in the 21st century and its impact on the Gulf of Mexico. J. Geophys. Res., 117, C05039, doi:10.1029/2011JC007555
Wang, C., S. Dong, A. T. Evan, G. R. Foltz and S.-K. Lee, 2012: Multidecadal co-variability of North Atlantic sea surface temperature, African dust, Sahel rainfall and Atlantic hurricanes. J. Climate, 25, 5404-5415, doi:10.1175/JCLI-D-11-00413.1.
Lee, S.-K., W. Park, E. van Sebille, M. O. Baringer, C. Wang, D. B. Enfield, S. Yeager and B. P. Kirtman, 2011: What caused the significant increase in Atlantic ocean heat content since the mid-20th century? Geophys. Res. Lett., 38, L17607, doi:10.1029/2011GL048856. [highlighted in Oct. 6, 2011 issue of Nature as Community Choice]
Lee, S.-K., D. B. Enfield and C. Wang, 2011: Future impact of differential inter-basin ocean warming on Atlantic hurricanes. J. Climate, 24, 1264-1275.
Muhling, B. A., S.-K. Lee, J. T. Lamkin and Y. Liu, 2011: Predicting the effects of climate change on bluefin tuna (Thunnus thynnus) Spawning habitat in the Gulf of Mexico. ICES J. Mar. Sci., 68, 1051-1062, doi:10.1093/icesjms/fsr008.
Wang, C., H. Liu, S.-K. Lee and R. Atlas, 2011: Impact of the Atlantic warm pool on United States landfalling hurricanes. Geophys. Res. Lett., doi:10.1029/2011GL049265. [highlighted in Oct. 21, 2011 issue of Sciecne as Editor's Choice]
Lee, S.-K., C. Wang and D. B. Enfield, 2010: On the impact of central Pacific warming events on Atlantic tropical storm activity. Geophys. Res. Lett., 37, L17702, doi:10.1029/2010GL044459.
Lee, S.-K. and C. Wang, 2010: Delayed advective oscillation of the Atlantic thermohaline circulation. J. Climate, 23, 1254-1261.
Wang, C. and S.-K. Lee, 2010: Is hurricane activity in one basin tied to another? EOS, 91, 93-94, doi:10.1029/2009ES002729.
Wang, C., S.-K. Lee and C. R. Mechoso, 2010: Inter-hemispheric influence of the Atlantic warm pool on the southeastern Pacific. J. Climate, 23, 404-418.
Wang, C., H. Liu and S.-K. Lee, 2010: The record-breaking cold temperatures during the winter of 2009/10 in the Northern Hemisphere. Atmos. Sci. Lett., doi:10.1002/asl.278.
DiNezio, P. N., A. C. Clement, G. A. Vecchi, B. J. Soden, B. P. Kirtman and S.-K. Lee, 2009: Climate response of the equatorial Pacific to global warming. J. Climate, 22, 4873-4892.
Lee, S.-K., C. Wang and B. E. Mapes, 2009: A simple atmospheric model of the local and teleconnection responses to tropical heating anomalies. J. Climate, 22, 272-284.
Wang, C. and S.-K. Lee, 2009: Co-variability of tropical cyclones in the North Atlantic and the eastern North Pacific. Geophys. Res. Lett., 36, L24702, doi:10.1029/2009GL041469.
Wang, C. and S.-K. Lee, 2009: Reply to comment by Joseph J. Barsugli on "Global warming and United States landfalling hurricanes". Geophys. Res. Lett., 36, L01706, doi:10.1029/2008GL035111.
Lee, S.-K., D. B. Enfield and C. Wang, 2008: Why do some El Ninos have no impact on tropical North Atlantic SST? Geophys. Res. Lett., 35, L16705, doi:10.1029/2008GL034734.
Lee, S.-K. and C. Wang, 2008: Tropical Atlantic decadal oscillation and its impact on the equatorial atmosphere-ocean dynamics: A simple model study. J. Phys. Oceanogr., 38, 193-212.
Wang, C. and S.-K. Lee, 2008: Global warming and United States landfalling hurricanes. Geophys. Res. Lett., 35, L02708, doi:10.1029/2007GL032396.
Wang, C., S.-K. Lee and D. B. Enfield, 2008: Atlantic warm pool acting as a link between Atlantic multidecadal oscillation and Atlantic tropical cyclone activity. Geochem. Geophys. Geosyst., 9, Q05V03, doi:10.1029/2007GC001809. [In the special issue of "Interactions between climate and tropical cyclones on all timescales"]
Wang, C., S.-K. Lee and D. B. Enfield, 2008: Climate response to anomalously large and small Atlantic warm pools during the summer. J. Climate, 21, 2437-2450.
Lee, S.-K., D. B. Enfield and C. Wang, 2007: What drives seasonal onset and decay of the Western Hemisphere warm pool? J. Climate, 20, 2133-2146.
Wang, C. and S.-K. Lee, 2007: Atlantic warm pool, Caribbean low-level jet, and their potential impact on Atlantic hurricanes. Geophys. Res. Lett., 34, L02703, doi:10.1029/2006GL028579.
Wang, C., S.-K. Lee and D. B. Enfield, 2007: Impact of the Atlantic warm pool on the summer climate of the Western Hemisphere. J. Climate, 20, 5021-5040.
Enfield, D. B., S.-K. Lee and C. Wang, 2006: How are large Western Hemisphere warm pools formed?. Prog. Oceanogr., 70, 346-365.
Pelegri, J. L., J. H. Churchill, A. D. Kirwan, Jr., S.-K. Lee, R. E. Munn and N. R. Pettigrew, 2006: Gabriel T. Csanady: Understanding the physics of the ocean. Prog. Oceanogr., 70, 91-112.
Wang, C., D. B. Enfield, S.-K. Lee and C. W. Landsea, 2006: Influences of Atlantic Warm Pool on Western Hemisphere Summer Rainfall and Atlantic Hurricanes. J. Climate, 19, No. 12, 3011-3028.
Enfield, D. B. and S.-K. Lee, 2005: The heat balance of the Western Hemisphere warm pool. J. Climate, 18, 2662-2681.
Lee, S.-K., D. B. Enfield and C. Wang, 2005: Ocean General Circulation Model Sensitivity Experiments on the Annual Cycle of Western Hemisphere Warm Pool. J. Geophys. Res. Ocean, 110, C09004, doi:10.1029/2004JC002640.
[Pre - 2005]
Thacker, C. W., S.-K. Lee and G. R. Halliwell Jr., 2004: Assimilating 20 years of Atlantic XBT data into HYCOM: A first look. Ocean Modelling, 7, 183-210.
Lee, S.-K., J. L. Pelegri and J. Kroll, 2001. Slope control in western boundary currents. J. Phys. Oceanogr., 31, 3349-3360.
Lee, S.-K., 2001: On the structure of supercritical western boundary currents. Dynam. Atmos. Oceans, 33, 303-319.
Lee, S.-K. and G. T. Csanady, 1999: Warm water formation and escape in the upper tropical Atlantic Ocean: Part I. a literature review. J. Geophys. Res. Ocean, 104, c12, 29561-29571.
Lee, S.-K. and G. T. Csanady, 1999: Warm water formation and escape in the upper tropical Atlantic Ocean: Part II. a numerical model study. J. Geophys. Res. Ocean, 104, c12, 29573-29590.
Lee, S.-K., 1999: Self-excited variability of the East Korean Warm Current: A quasi-geostrophic model study. J. Korean Soc. Oceanogr., 34, 1-21.
Lee, S.-K. and G. T. Csanady, 1994: Instability waves in the Gulf Stream front and its thermocline layer. J. Mar. Res., 52, 837-863.