Randall, D.A., D. Dazlich, L. Fowler, D.-M. Pan, P. Sellers,
and C.-H. Chen, 1995: The CSU AMIP runs. Abstracts of the First International
AMIP Scientific Conference, Monterey, California, 90.
The Colorado State University (CSU) atmospheric general circulation
model (GCM) completed its first AMIP simulation (CSU91) in 1991. A second
simulation (CSU94) was conducted in 1994, after three major changes had
been made to the model, namely:
-
The cumulus parameterization was revised to make use of a prognostic cumulus
kinetic energy;
-
SiB2, the second-generation version of the land surface parameterization
developed by P. Sellers and colleagues, was installed in the GCM;
-
The stratiform cloud microphysics parameterization developed by L. Fowler
and colleagues was adopted.
This first round of changes to the model led to improvements in the simulation
of the Earth's radiation budget and cloudiness, as surface air temperature,
snow cover, the Indian summer monsoon circulation, and the precipitation
rate.
A third AMIP run (CSU95) is now being conducted. This version of the
model includes a gravity wave drag parameterization developed by Kim and
Arakawa at UCLA, and also a simple convective downdraft parameterization
developed at CSU by C.-H. Chen and D. Randall. In addition, for AMIP95
the top of the model has been raised to the 1 mb level, whereas in AMIP91
and AMIP94 it had been at the 50 mb level. Preliminary results indicate
that CSU95 has more realistic zonal winds, precipitation rate, and tropical
thermodynamic structure. The simulated Indian summer monsoon has also improved
further.