George C. Craig
DLR Institut für Physik der Atmosphäre, Oberpfaffenhofen
Equilibrium Statistical Mechanics of Moist Atmospheric Convection
Abstract:
Equilibrium Statistical Mechanics of Moist Atmospheric Convection
George C. Craig, DLR Institut für Physik der Atmosphäre,
Oberpfaffenhofen
Cumulus clouds, because of their small size and rapid evolution,
provide a stochastic forcing for the large-scale dynamics of the
atmosphere. However, this stochastic aspect is usually ignored
in climate and weather prediction models, and replaced by a
slowly varying forcing based on an assumption
of equilibrium, in which the large scales interact deterministically
with the statistical properties of the convection.
This is a statistical equilibrium like turbulence or gas kinetics,
and to understand how the stochastic component should be incorporated,
it is necessary to examine the underlying processes at the "microscopic"
level.
This talk will develop a statistical characterisation of the
convective scale behaviour, given the large scale environment,
and show results from tests of the theory using a cloud-resolving
model. Specifically, we will consider
- The time scale of adjustment to equilibrium
- Length scale of the convective variability
- Magnitude of the fluctuations about the
equilibrium mean
A stochastic convection parameterisation
(forcing function) based on this
theory is being developed, and some results from
single column,
radiative-convective equilibrium experiments
will be shown.
| Zeit: | Freitag, 15. April, 2005, 14.15 (Kaffee/Tee um 15.30) |
| Ort: | FU Berlin, Arnimallee 2-6, Raum 032 im EG |