Cloud Physics and Dynamics
Offices: Burnside Hall 944 | 818
Tel.: (514) 398-3719
Fax.: (514) 398-6115
peter [dot] yau [at] mcgill [dot] ca (E-mail)
Studies in hurricanes
Hurricanes represent one of the most violent weather phenomena. They form in the low latitudes but can also affect Canada when they move northward. Our work involves using high resolution numerical models to simulate these storms. Diagnostic studies are being conducted to understand the internal structure of the eye and eyewall, the waves propagating in the system, and the effect of wave mean flow interaction on the intensity change of hurricanes. We have applied novel analysis techniques, like empirical normal modes, to study wave activities in hurricanes. Recent case studies include hurricanes Andrew, Earl, Isabel, and Floyd.
We have developed simple and complex models to study the interactions of various physical processes in convective clouds. Our recent work includes simulation of the mechanism of mixing, and entrainment in cumulus clouds, the interactions involving radiation and cloud dynamics, and the effects of stochastic condensation and droplet collision in turbulence on the size spectra of cloud droplets.
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Severe weather over Alberta
Tornadic storms and hailstorms are extreme weather events over Alberta. We have carried out meso and synoptic scale analyses which showed that severe convection was triggered by a proper phasing of an advancing, synoptic scale trough and the mountain-plain circulation driven by strong surface radiation heating over the Alberta foothills. Concurrently, the northeasterly flow at the surface advects the moist plains air into the lower branch of the mountain plain circulation to effectuate a secondary destabilization leading to the outbreak of severe hail storms. We are carrying out high resolution experiments to validate these observations using the Canadian Mesoscale Compressible Community Model (MC2). Numerical modeling of tornadic storms is underway to understand the mechanism for tornadogenesis.
Simulation of high and low-latitude precipitation systems
We are studying processes in precipitation systems both in high latitudes and in the tropics through high-resolution modeling. Recent work includes simulation of blowing snow over the Mackenzie River Basin, and tropical clusters over TOGA COARE.
Improving quantitative precipitation forecasts
To improve 24-48 hr. precipitation forecasts using mesoscale models, we are performing research to: a) improve the initial conditions through assimilation of rainfall rates using variational techniques and key analysis error algorithms, and b) improve the representation of cloud processes in numerical models through the development of new multi-moment microphysics schemes and parameterization for autoconversion of cloud water to rain water in a turbulent cloud.
For a complete list of publication, please see Google Scholar.