Dr. Keith Ngan obtained his B.Sc. in Physics and Chemistry from the University of British Columbia and his M.Sc. and Ph.D. in Physics from the University of Toronto. Subsequently he was a postdoctoral fellow at the University of Chicago and a research associate at McGill University. In 2008 he moved to the UK Met Office, where he worked as a senior research scientist in the numerical weather prediction division. In 2013 he joined City University of Hong Kong as an Assistant Professor in the School of Energy and Environment.
Dr. Ngan's research seeks to improve understanding of basic dynamical processes in the atmosphere through high-resolution numerical modelling. He is especially interested in interdisciplinary research, more specifically the application of techniques and approaches from applied mathematics and fluid dynamics to practical atmospheric problems. His main areas of expertise are turbulence, data assimilation, atmospheric modelling and scalar mixing and dispersion. The current focus of his research is urban boundary-layer meteorology.
- G.E Lau & K. Ngan, 2018: Analysing urban ventilation in building arrays with the age spectrum and mean age of pollutants, Building and Environment, in press, doi:10.1016/j.buildenv.2018.01.010.
- G. Duan & K. Ngan, 2018: Effects of Time-Dependent Inflow Perturbations on Turbulent Flow in a Street Canyon, Boundary-Layer Meteorology, in press, doi:10.1007/s10546-017-0327-1
- K.W. Lo & K. Ngan, 2017: Characterising urban ventilation and exposure using Lagrangian particles. Journal of Applied Meteorology and Climatology, 56, 1177-1194, doi:10.1175/JAMC-D-16-0168.
- K. Ngan & K.W. Lo, 2017: Linear error dynamics for turbulent flow in urban street canyons. Journal of Applied Meteorology and Climatology, 56, 1195-1208, doi:10.1175/JAMC-D-16-0173.1
- K. Ngan & K.W. Lo, 2016: Revisiting the flow regimes for urban street canyons using the numerical Green's function, Environmental Fluid Mechanics, 16, 313–334. doi:10.1007/s10652-015-9422-3.
- KW Lo & K Ngan, 2015: Characterising the pollutant ventilation
characteristics of street canyons using the tracer age and age spectrum, Atmospheric Environment, 122,
- K Ngan & KW Lo, 2015:
Revisiting the flow regimes for urban street canyons using the numerical
Green's function, Environmental Fluid
Mechanics, 16, 313-334, DOI:10.1007/s10652-015-9422-3.
- KW Lo & K Ngan, 2015:
Predictability of turbulent flow in street canyons, Boundary-Layer Meteorology, 156, 191-210, DOI:10.1007/s10546-015-0014-z.
- MJP Cullen & K Ngan,
2013: On the relationship between stratospheric structure and blocking, Philosophical Transactions of the Royal Society A,
371, 2012018, DOI:10.1098/rsta.2012.0180.
- N.B. Ingleby,
A.C. Lorenc, K. Ngan, R. Rawlins & D.R. Jackson,
2012: Improved variational analyses using a nonlinear
humidity control variable, Quarterly
Journal of the Royal Meteorological Society, 139, 1875-1887, DOI:10.1002/qj.2073.
- K. Ngan & G.E. Eperon, 2012: Middle atmosphere predictability in a
Numerical Weather Prediction Model, Quarterly
Journal of the Royal Meteorological Society, 138, 1366-1378, DOI:10.1002/qj.984.
- K. Ngan & J. Vanneste, 2011: Scalar decay in a three-dimensional chaotic
flow, Physical Review E,
83, 056306, DOI:10.1103/PhysRevE.83.056306.
- K. Ngan, P. Bartello & D.N. Straub, 2009: Predictability of
rotating stratified turbulence, Journal
of the Atmospheric Sciences, 66, 1384 – 1400, DOI:10.1175/2008JAS2799.1.
- K. Ngan, P. Bartello & D.N. Straub, 2008: Dissipation of
synoptic-scale flow by small- scale turbulence, Journal of the Atmospheric Sciences, 65, 766 – 791, 10.1175/2007JAS2265.1.
- K. Ngan, D.N. Straub
& P. Bartello, 2005: Aspect ratio effects in
quasi-two- dimensional turbulence. Physics
of Fluids, 17, 125102-1 –125102-17, DOI:10.1063/1.2139685.
- K. Ngan, D.N. Straub
& P. Bartello, 2004: Three-dimensionalization of freely-decaying two-dimensional turbulence. Physics of Fluids, 16, 2918 – 2932, DOI:10.1063/1.1763191.
- T.G. Shepherd, J.N. Koshyk & K. Ngan, 2000: On the nature of large-scale
mixing in the stratosphere and mesosphere. Journal
of Geophysical Research, 105, 12,433 – 12,460.
- K. Ngan & R.T. Pierrehumbert, 2000: Spatially correlated and inhomogeneous
random advection. Physics of Fluids,
12, 822 – 834.
- K. Ngan & T.G.
Shepherd, 1999: A closer look at chaotic advection in the stratosphere. Part I.
Geometrical Structure. Journal of the
Atmospheric Sciences, 56, 4134 – 4153.
- K. Ngan & T.G.
Shepherd, 1999: A closer look at chaotic advection in the stratosphere. Part
II. Statistical diagnostics. Journal of
the Atmospheric Sciences, 56, 4154 – 4169.
- K. Ngan & T.G.
Shepherd, 1997: Chaotic mixing and transport in Rossby-wave
critical layers. Journal of Fluid
Mechanics. 334, 315 – 351.
- K. Ngan & T.G.
Shepherd, 1997: Comments on some recent measurements of anomalously steep N2O
and O3 tracer spectra in the stratospheric surf zone. Journal of Geophysical Research, 102,
24,001 – 24,004.
- K. Ngan, S. Meacham &
P.J. Morrison, 1996: Elliptical vortices in shear: Hamiltonian moment
formulation and Melnikov analysis. Physics of Fluids, 8, 896 – 913.
- Atmospheric Science Seminar, National Central University, Jhongli, Taiwan, June 2017
- "Dispersion and ventilation in urban street canyons", School of Mathematics, University of Edinburgh, December 2016.
- "Atmospheric predictability from global to urban scales", Earth System Science Programme, Chinese University of Hong Kong, November 2016.
- "Characterising urban ventilation and exposure with Lagrangian diagnostics", Workshop on Photochemical Smog in China, October 2016.
- "Some issues in urban-scale NWP", Numerical Weather Prediction Forum, Hong Kong Observatory, March 2016.
- "Predictability and linear error dynamics of turbulent flow in street canyons", American Met. Society Joint Conference on Air Pollution Meteorology and its Applications, January 2016.
- Ventilation and
mixing timescales for urban air quality (Supported
by the Research Grants Council of Hong Kong, 2015-2018; with K.K. Hon, Hong
- Regional vs. local
contributions to particulate concentrations in street canyons (Supported by the Environment and
Conservation Fund and Woo Wheelock Green Fund, 2016-2018; with Prof. P. Brimblecombe and Dr. Z. Ning, SEE/CityU)
- Applications of
wavelets and multiscale modelling to urban canopy parameterisations (Supported by the Research Grants Council
of Hong Kong, 2016-2019; with Prof. P. Bartello,
McGill University and K.K. Hon, Hong Kong Observatory)
- Effects of elevated
walkways on urban flow and dispersion (Co-I;
with Prof. P. Brimblecombe, SEE)
- Random-walk models of
urban pollutant dispersion (with Prof. J. Vanneste, University of Edinburgh)
- Predicting winds inside deep urban canopies using vortex dynamics (Supported by the Research Grants Council of Hong Kong, 2018-2020; with K.K. Hon, Hong Kong Observatory)
'Research opportunities are available for undergraduate and postgraduate students with interests in computational fluid dynamics, urban air quality, mathematical modelling or atmospheric science
- Guangdong Duan (PhD, City University of Hong Kong)
- Postdoctoral fellows
- Ghar Ek Lau (PhD, University of New South Wales; 2016 - 2018)
- Gantuya Ganbat (PhD, Seoul National University; 2016 - 2018)
- James G. Jackson (PhD University College London), April 2015 - date
- Ka Wai Lo (PhD University of Illinois at Urbana-Champaign; 2013 – 2016)
- Research Assistants
- Jason Y.L. Chu (now at Hong Kong University of Science and Technology)
- BEng Final-Year Project Students
- G. Xu (Now MSc, Columbia University)
- N. Kong (Now MEng, University of Michigan)
- Summer interns
- K.W. Wong (currently MSc at École Polytechnique Fédérale de Lausanne)
- T. Ying (2014; currently PhD at University of Edinburgh)