EOS and Mathematics Seminar
Monday, Sept. 30th, 10:00 a.m.
Room 330A Earth and Ocean Sciences Main Bldg.
(formerly Geological Sciences Building)
University of Toronto
Gravity wave drag parameterization in models of the quasi-biennial oscillation
A major failing of large-scale general circulation models (GCMs) of
the atmosphere has been their inability to simulate phenomena such as
the quasi-biennial oscillation (QBO). This is an oscillation between
westerly and easterly zonal mean winds observed in the equatorial
stratosphere. It is driven by vertically-propagating waves
(planetary-scale waves and gravity waves) which transport momentum and
energy upwards from the troposphere. Gravity waves, because of their
small scale, are generally unresolved in GCMs, so for the models to be
able to simulate the QBO, the drag due to these waves must be
accounted for by means of a parameterization. I have been studying
gravity wave drag parameterization schemes and I shall give an
overview of my work in this talk. I have determined the constraints
that are needed for each of these schemes to be able to generate a QBO
in a one- or two-dimensional model. These constraints can be
generalized ultimately for improving the representation of gravity
wave drag in GCMs. I shall also discuss a model for the QBO that I am
developing, which is based on nonlinear interactions of
upward-propagating waves at their critical levels.
Please attend this seminar to be given by Dr. Lucy Campbell.
She is a candidate for a UFA in the Department of Mathematics.