Dr Yueng-Djern Lenn
Senior Lecturer in Physical Oceanography
I am a polar physical oceanographer and my interests lie in understanding the physical processes integral to ocean overturning that impact climate in the polar oceans. My Southern Ocean research has focused on Drake Passage eddy heat and momentum fluxes, the surface Ekman layer that constitute the upper limb of the overturning circulation, and diapycnal mixing driving water mass transformation in the thermocline at the Antarctic continental slope. My Arctic research focuses on water mass transformations occurring in the continental shelf seas and along the Arctic continental slope that link the Arctic to the global overturning circulation, so far focusing on the role of different mixing mechanisms (i.e. double diffusion and turbulent mixing drive by tides or winds) in fluxing heat and other properties from the warm Atlantic Water into overlying Arctic halocline and mixed layer.
Current Phd Students: Ben Barton, Universite de Bretagne Occidentale
ONS1001: Environmental Data & Analysis
DXX1005: Earth Systems & Processes
OSX1005: Introducing the Oceans
OSX2005: Earth and Ocean Observation
OSX2006: TIdes, Waves & Sampling
OSX3002: Marine Ecosystems & Processes
OSX4010: Key Concepts & Techniques
OSX4012: Practical Oceanography
OSX4015: Climate & Climate Change
OSX4408: Field and Lab Oceanography
At present, my research interests are focused in the following areas:
1. Physical processes that drive vertical mixing of heat, freshwater and nutrients in the upper ocean of the Arctic on both the shelves and deeper basins. These processes include convection at the ice-ocean interface, double diffusion, turbulent mixing driven by tides or winds, and mesoscale eddies and their interactions with fronts.
2. The role of tidally-rectified flow in creating pathways for densest shelf waters to navigate the shelf sea of the Antartic and Arctic, and the consequences for water mass transformation on route.
- Wind-driven mixing at intermediate depths in an ice-free Arctic OceanLincoln, B, Rippeth, T, Lenn, Y-D, Timmermans, M-L, Willaims, W & Bacon, S 2016, 'Wind-driven mixing at intermediate depths in an ice-free Arctic Ocean' Geophysical Research Letters, vol 43, no. 18, pp. 9749-9756. DOI: 10.1002/2016GL070454
- Kara Sea freshwater transport through Vilkitsky Strait: Variability, forcing, and further pathways toward the western Arctic Ocean from a model and observationsJanout, MA, Aksenov, Y, Holemann, JA, Rabe, B, Schauer, U, Polyakov, IV, Bacon, S, Coward, AC, Karcher, M, Lenn, Y, Kassens, H & Timokhov, L 2015, 'Kara Sea freshwater transport through Vilkitsky Strait: Variability, forcing, and further pathways toward the western Arctic Ocean from a model and observations' Journal of Geophysical Research: Oceans, vol 120, no. 7, pp. 4925-4944. DOI: 10.1002/2014JC010635
- Tide-mediated warming of Arctic halocline by Atlantic heat fluxes over rough topographyRippeth, TP, Lincoln, BJ, Lenn, YD, Green, JA, Sundfjord, A & Bacon, S 2015, 'Tide-mediated warming of Arctic halocline by Atlantic heat fluxes over rough topography' Nature Geoscience, vol 8, no. 3, pp. 191-194. DOI: 10.1038/NGEO2350
- Observations of a diapycnal shortcut to adiabatic upwelling of Antarctic Circumpolar Deep WaterSilvester, JM, Lenn, YD, Polton, JA, Rippeth, TP & Maqueda, MM 2014, 'Observations of a diapycnal shortcut to adiabatic upwelling of Antarctic Circumpolar Deep Water' Geophysical Research Letters, vol 41, no. 22, pp. 7950-7956. DOI: 10.1002/2014GL061538
- Semidiurnal Tides on the Laptev Sea Shelf with Implications for Shear and Vertical MixingJanout, MA & Lenn, YD 2014, 'Semidiurnal Tides on the Laptev Sea Shelf with Implications for Shear and Vertical Mixing' Journal of Physical Oceanography, vol 44, no. 1, pp. 202-219. DOI: 10.1175/JPO-D-12-0240.1
- Can Drake Passage Observations Match Ekman's Classic Theory?Polton, JA, Lenn, Y, Elipot, S, Chereskin, TK & Sprintall, J 2013, 'Can Drake Passage Observations Match Ekman's Classic Theory?' Journal of Physical Oceanography, vol 43, no. 8, pp. 1733-1740. DOI: 10.1175/JPO-D-13-034.1
- Shear at the Base of the Oceanic Mixed Layer Generated by Wind Shear AlignmentBrannigan, L, Lenn, YD, Rippeth, TP, McDonough, E, Chereskin, TK & Sprintall, J 2013, 'Shear at the Base of the Oceanic Mixed Layer Generated by Wind Shear Alignment' Journal of Physical Oceanography, vol 43, no. 8, pp. 1798-1810. DOI: 10.1175/JPO-D-12-0104.1
- Mooring-Based Observations of Double-Diffusive Staircases over the Laptev Sea SlopePolyakov, IV, Pnyushkov, AV, Rember, R, Ivanov, VV, Lenn, YD, Padman, L & Carmack, EC 2012, 'Mooring-Based Observations of Double-Diffusive Staircases over the Laptev Sea Slope' Journal of Physical Oceanography, vol 42, no. 1, pp. 95-109. DOI: 10.1175/2011JPO4606.1
- Intermittent intense turbulent mixing under ice in the Laptev Sea continental shelf.Lenn, Y, Rippeth, TP, Old, C, Bacon, S, Polyakov, I, Ivanov, V & Holemann, J 2011, 'Intermittent intense turbulent mixing under ice in the Laptev Sea continental shelf.' Journal of Physical Oceanography, vol 41, no. 3, pp. 531-547. DOI: 10.1175/2010JPO4425.1
- Vertical mixing at intermediate depths in the Arctic boundary current.Lenn, YD, Wiles, PJ, Torres-Valdes, S, Abrahamsen, EP, Rippeth, TP, Simpson, JH, Bacon, S, Laxon, SW, Polyakov, I, Ivanov, V & Kirillov, S 2009, 'Vertical mixing at intermediate depths in the Arctic boundary current.' Geophysical Research Letters, vol 36, pp. L05601. DOI: 10.1029/2008GL036792
- Observations of Ekman currents in the southern ocean.Lenn, YD & Chereskin, TK 2009, 'Observations of Ekman currents in the southern ocean.' Journal of Physical Oceanography, vol 39, no. 3, pp. 768-779. DOI: 10.1175/2008JPO3943.1
- Improving estimates of the Antarctic circumpolar current streamlines in Drake Passage.Lenn, YD, Chereskin, TK & Sprintall, J 2008, 'Improving estimates of the Antarctic circumpolar current streamlines in Drake Passage.' Journal of Physical Oceanography, vol 38, no. 5, pp. 1000-1010. DOI: 10.1175/2007JPO3834.1
2010-2015 NERC Postdoctoral Fellowship Principle Investigator
2011-2016 TEA-COSI:The Environment of the Arctic: Climate, Ocean and Sea-Ice UK NERC Consortium: Including Lenn (Project Partner, Bangor.)
2012-2015 Upper ocean heat flux in the Eurasian Basin: Oceanic thermodynamic forcing contributing to Arctic ice loss. USA National Science Foundation grant including Lenn (Project Partner, Bangor)
As schools liason for the School of Ocean Sciences, I co-ordinate most visits to Ocean Sciences by schools as well as provide support for colleagues who visit schools. Other outreach events I support include school STEM Careers Fairs and other Science Fairs. These activities include events organised in partnership with STEMCymru and other similar organisations seeking to promote STEM in Wales and beyond.
I strive for a life that balances faith, family and work, seeking to live a life that is consistent with my values and always consious of the importance of being a good role model. At present, my personal life is dominated by raising my young family with my husband, another physical oceanographer Jeff Polton. Together as a family, and occasionally individually, we pursue a pretty active life featuring as much swimming, hiking, cycling and general exploration of the great outdoors and underwater (and in as many far flung locations our work lives take us) as possible. And upon return home, we find much pleasure in books, Lego, superhero movies and comics, music and dance.