Dr Yueng-Djern Lenn

Photograph of Dr Yueng-Djern Lenn

Biography

November 2016 - present: Senior Lecturer in Physical Oceanography, School of Ocean Sciences, Bangor University
January 2015 - 2016: Lecturer in Physical Oceanography, School of Ocean Sciences, Bangor University
October 2010 - January 2015: NERC Postdoctoral Fellow, School of Ocean Sciences, Bangor University
November 2007 - September 2010: Postdoctoral Researcher, School of Ocean Sciences, Bangor University
October 2006 - October 2007: Postdoctoral Researcher, Scripps Institution of Oceanography, University of California, San Diego

Education

2006: Ph.D., Oceanography, Scripps Institution of Oceanography, University of California at San Diego.
1998: M.Sc., Radiation Physics - Medical Applications, University College London, U.K.
1997: B.A. Hons, Physics, University of Cambridge, U.K.

Research Interests

My research focuses on the physical mechanisms driving heat and freshwater fluxes across constant density surfaces (isopycnals) and latitudes in the polar oceans and how these feedback on climate.

In the Arctic, double diffusive convection, ubiquitous in the central Arctic basins, is considered an important mechanistic pathway for the heat from the warm salty Atlantic Water inflow to penetrate the halocline and reach the surface mixed layer that is in contact with the sea ice. Observations show that the thermal-salinity structure of these double diffusive convection staircases varies considerably across the Arctic. My current research focuses on how the underlying stratification (i.e. background density field set by temperature and salinity) and ocean currents impact the formation of these staircases, and heat and freshwater are fluxed through them.

In the Southern Ocean dynamics, the energetic mesoscale eddies are responsible for fluxing heat across the large-scale Antarctic Circumpolar Currents, while water mass transformation of Circumpolar Deep Water upwelling into the surface mixed layer are the critical means by which heat and freshwater are exchanged between the ocean carrying water south and atmosphere and cryosphere. Thus these water mass transformations drive the Southern Ocean;s overturning circulation which has a key role in the Earth’s climate. My research focuses on the mechanisms responsible for water mass transformation along the Antarctic continental slope.

Teaching

DXX1005: Earth Systems and Processes
ONS1001: Introductory Research Skills
OSX2005: Earth and Ocean Observation
OSX2006: Tides, Waves and Sampling
OSX3002: Marine Ecosystems and Processes
OSX4012: Practical Oceanography
OSX4015: Climate and Climate Change
OSX4408: Field & Lab Oceanography

Links

Publications

Peer Reviewed Journal Papers

Janout, M et al. including Lenn, Y.-D, 2015
Forcing, variability, and pathway of a Siberian buoyancy - driven current and its implications for the Arctic freshwater budget, J. Geophys. Res., 120(7) 4925-4944.

Rippeth, Tom P., Ben J. Lincoln, Yueng-Djern Lenn, J. A. Mattias Green, Arild Sundfjord and Sheldon Bacon (2015).
Tide-mediated warming of Arctic halocline by Atlantic heat fluxes over rough topography. Nature Geoscience, DOI: 10.1038/NGEO2350

Markus A. Janout, Yueng-Djern Lenn (2014)
Semidiurnal Tides on the Laptev Sea Shelf with Implications for Shear and Vertical Mixing. Journal of Physical Oceanography, 44(1), 202-219.

Mead Silvester, J., Y.-D. Lenn, J. A. Polton, T. P. Rippeth, and M. Morales Maqueda (2014)
Observations of a diapycnal shortcut to adiabatic upwelling of Antarctic Circumpolar Deep Water, Geophys. Res. Lett., 41, 7950-7956.
View website

Brannigan, Liam; Lenn, Yueng-Djern; Rippeth, Tom P.; Elaine McDonagh, TK Chereskin and Janet Sprintall (2013)
Shear at the Base of the Oceanic Mixed Layer Generated by Wind Shear Alignment. Journal of Physical Oceanography Volume: 43 Issue: 8 Pages: 1798-1810 DOI: 10.1175/JPO-D-12-0104.1

Polton, Jeff A., Lenn, Yueng-Djern, Elipot, Shane, et al (2013)
Can Drake Passage Observations Match Ekman's Classic Theory? Journal of Physical Oceanography, 43(8), 1733-1740.

Dmitrenko, Igor A., Kirillov, Sergey A., Bloshkina, Ekaterina, Lenn, Yueng-Djern (2012).
Tide-induced vertical mixing in the Laptev Sea coastal polynya. J. Geophys. Res., 117, C00G14

Igor V. Polyakov, Andrey V. Pnyushkov, Robert Rember, Vladimir V. Ivanov, Y.-D. Lenn, Laurie Padman, Eddy C. Carmack
Mooring-Based Observations of Double-Diffusive Staircases over the Laptev Sea Slope. Journal of Physical Oceanography 42 95-109.
View website

Lenn, Y.-D., Chereskin, T. K., Sprintall, J., McClean, J. L., (2011)
Near-surface eddy heat and momentum fluxes in the Antarctic Circumpolar Current in Drake Passage. Journal of Physical Oceanography, 41 (7), 1385-1407.

Meredith, MP; Woodworth, P: Chereskin, T; Marshall, DP; Allison, LC; Bigg, GR; Donohue, K; Heywood, KJ; Hughes, CW; Hibbert, A; Hogg, AM; Johnson, HL; Jullion, J; King, BA; Leach, H; Lenn, YD; Maqueda, MAM; Munday, DR; Garabato, ACN; Provost, C; Sallee, JB; Sprintall, J (2011)
Sustained monitoring of the Southern Ocean at Drake Passage: 3 past achievements and future priorities Reviews of Geophysics 49 RG4005, 36 PP doi:10.1029/2010RG000348

Polyakov, Igor V. , Vladimir A. Alexeev, Igor M. Ashik, Sheldon Bacon, Agnieszka Beszczynska-Möller, Eddy C. Carmack, Igor A. Dmitrenko, Louis Fortier, Jean-Claude Gascard, Edmond Hansen, Jens Hölemann, Vladimir V. Ivanov, Takashi Kikuchi, Sergey Kirillov, Yueng-Djern Lenn, Fiona A. McLaughlin, Jan Piechura, Irina Repina, Leonid A. Timokhov, Waldemar Walczowski, Rebecca Woodgate (2011).
Fate of Early 2000s Arctic Warm Water Pulse. Bulletin of the American Meterological Society, 92(5), 561-566.

Yueng-Djern Lenn, Tom P. Rippeth, Chris P. Old, Sheldon Bacon, Igor Polyakov, Vladimir Ivanov, Jens Hölemann (2011).
Intermittent Intense Turbulent Mixing under Ice in the Laptev Sea Continental Shelf. Journal of Physical Oceanography, 41(3), 531-547

Yueng -Djern Lenn (2009).
How Atlantic Water is Cooled in the Arctic Refrigerator. Ocean Challenge, 16(3), 28-31

Yueng-Djern Lenn and Teresa K. Chereskin (2009).
Observations of Ekman Currents in the Southern Ocean. Journal of Physical Oceanography, 39, 768-779.

Yueng-Djern Lenn, Wiles, P. J., Torres-Valdes, S., Abrahamsen, E. P., Rippeth, T. P., Simpson, J. H., Bacon, S., Laxon, S. W., Polyakov, I., Ivanov, V., Kirillov, S. (2009)
Vertical mixing at intermediate depths in the Arctic boundary current. Geophysical Research Letters, 36 (5). 5, pp. doi:10.1029/2008GL036792

Lenn, Y.-D., T.K. Chereskin and J. Sprintall, 2008
Improving Estimates of the Antarctic Circumpolar Current Streamlines in Drake Passage, J. Phys. Oceanogr., 38 (5), 1000-1010.

Lenn, Y.-D., T.K. Chereskin, J. Sprintall and E. Firing. 2007
Mean Jets, Mesoscale Variability and Eddy Momentum Fluxes in the Surface- Layer of the Antarctic Circumpolar Current in Drake Passage, J. Mar. Res., 65, 27-58.

Beal, L. M., T. K. Chereskin, Y.-D. Lenn and S. Elipot. 2006
Sources and Mixing Characteristics of the Agulhas Current, J. Phys. Oceanogr., 36 (11), 2060-2074.

Lenn, Y.-D., T.K. Chereskin and R.C. Glatts. 2003
Seasonal to tidal variability in currents, stratification and acoustic backscatter in Antarctic ecosystem at Deception Island, Deep-Sea Research Part II-Topical Studies in Oceanography, 50 (10-11), 1665-1683

PDF copies of some of these publications are available (as indicated by hyperlinks in the list) for non-commercial research and educational purposes only. You may not use the material for commercial purposes or make multiple copies without requesting permission from the copyright holder (usually the book or journal publisher).