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Gary Klaassen

Professor of Atmospheric Science



Phone Number: 416-736-2100 x77727



Gary Klaassen joined York University in 1986 after an Advanced Study Program Postdoctoral fellowship at the National Center for Atmospheric Research in Boulder, Colorado. He has a Ph.D. and M.Sc. in Atmospheric Physics from the University of Toronto and a B.Sc. in Physics from University of Waterloo.

Research Interests

Dr. Klaassen’s major research interests are in wave dynamics, stratified shear flows, the transition to turbulence, cloud dynamics and mesoscale meteorology. A variety of theoretical and numerical models are being employed to study the evolution and stability of nonlinear disturbances in the atmosphere. The goal is to improve our understanding the complex nature of small-scale flows, and their interactions with the larger scales associated and weather and climate systems.

Selected Publications

Medvedev, A. S., Klaassen, G. P., & Yĭgit, E. (2023). On the dynamical importance of gravity wave sources distributed over different heights in the atmosphere. J. Geophys Res: Space Physics. 128:

Majdzadeh, M. and Klaassen, G.P. (2019) An Analysis of the Hines and Warner-McIntyre-Scinocca Nonorographic Gravity Wave Drag Parameterizations, Quart. J. Roy. Met. Soc. 145, 2308-2334.

Klaassen, G. P.(2009). Testing Lagrangian Theories of Internal Wave Spectra. Part I: Varying the Amplitude and Wavenumbers. J. Atmos. Sci.66: 1077–1100.

Klaassen, G. P., and L. J. Sonmor. (2006). Does kinematic advection by superimposed waves provide an
explanation for quasi-universal gravity-wave spectra?. Geophys. Res. Lett.33(L23802): 1-5.

Yau, K.-H., Klaassen, G.P. and Sonmor, L. J. (2004). Principal Instabilities of Large Amplitude Inertio-gravity Waves. Phys. Fluids. 16: 936-951.

Medvedev, A.S., and Klaassen, G.P.(2001). Realistic Semiannual Oscillation Simulated in a Middle Atmosphere Model. Geophys. Res. Lett.28: 733-736.

Sonmor L. J. and Klaassen, G. P. (1997). Toward a unified theory of gravity-wave stability. J. Atmos. Sci. 54: 2655-2680.

Medvedev, A. S. and Klaassen, G. P. (1995). Vertical evolution of gravity-wave spectra and the parameterization of associated wave drag. J. Geophys. Res.100: 25841–25853.