The Numerical Simulation of Orographic Storms (Wales, Seeder-Feeder Mechanism, Bergeron)
Bradley, Michael Morgan
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/70918
Description
Title
The Numerical Simulation of Orographic Storms (Wales, Seeder-Feeder Mechanism, Bergeron)
Author(s)
Bradley, Michael Morgan
Issue Date
1985
Department of Study
Atmospheric Sciences
Discipline
Atmospheric Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Atmospheric Science
Abstract
Recent observational studies of winter storms over the Glamorgan Hills of south Wales (Browning et al., 1974, and Hill et al., 1981) have confirmed the importance of the seeder-feeder mechanism of orographic precipitation enhancement, proposed by Bergeron (1965). However, the latter study also indicated that the sensitivity of the enhancement to the low-level wind speed is much greater than predicted by the seeder-feeder model of Bader and Roach (1977), which simulates only the microphysical processes.
A new, dynamic mountain model was used to investigate the hypothesis that mountain wave effects were responsible for this increased wind speed sensitivity. The model, which evolved from the cloud model of Klemp and Wilhelmson (1978), is formulated in terrain-following coordinates. In addition to representing convective and stratiform cloud processes, the model is also capable of accurately simulating moderately nonlinear mountain waves, and is suitable for studying many aspects of orographic storms.
The simulations show that orographic clouds significantly alter the airflow over hills and, conversely, that mountain waves strongly influence the moist processes. Wind speed, wind shear, atmospheric stability, and relative humidity are all important factors in the complex scale interactions which occur during orographic storms. The results strongly support the hypothesis that certain mountain wave effects greatly increase the wind speed sensitivity of the Bergeron seeder-feeder mechanism.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
