Model NRL1: Elaborations
Participation
Model NRL1 is an entry in the CMIP1 intercomparison only.
Spinup/Initialization
The spinup/initialization procedure was as follows (cf. Li
and Hogan 1998 for further details):
-
The atmospheric model was integrated for 5 years with prescribed seasonally
varying SSTs, and the last 3 years were averaged to obtain an estimate
of annual-mean surface conditions.
-
The ocean model was integrated with these annual-mean forcings, while the
SSTs were relaxed toward their observed annual- mean values, until a quasi-equilibrium
state was achieved.
-
Annual-mean flux corrections for heat and momentum (i.e., surface-wind
forcing) to be supplied to the ocean model in coupled mode then were computed
from the differences between the fields simulated by the atmospheric model
with prescribed SSTs and the observations (for surface winds, the COADS
data set--cf. Sadler et al. 1987).
-
The atmosphere and ocean were coupled and integrated for 40 years with
application of these annual-mean flux corrections. Model data from the
last 36 years of this simulation were supplied for the CMIP I intercomparison.
Land Surface Processes
-
Soil temperatures are computed from a surface energy balance that includes
snowmelt as well as relaxation (with 100-hour time constant) to FNOC
(1986) monthly climatological deep-ground temperatures. These deep
temperatures are derived from observed surface atmospheric temperatures
that are lagged by one month, with annual cycle reduced by 30 percent.
The heat capacity specified for soil is also a nonlinear function of the
ground wetness, and the thermal conductivity of snow-covered ground is
set to about twice that of bare ground.
-
Soil hydrology is determined from a modified bucket model. Continental
runoff, which occurs locally when the moisture capacity of the bucket is
exceeded, does not contribute to the freshwater flux into the ocean model.
Cf. Hogan and Rosmond (1991) for
further details.
Sea Ice
Sea ice extents are prescribed, but some provision is made for predicting
temperature. More information needed.
References
FNOC, 1986: Fleet Numerical Oceanographic Center's
Numerical Environmental Products Manual, Vols. I and II. Fleet Numerical
Oceanographic Center, Monterey, CA, 214 pp.
Hogan, T. F., and T. E. Rosmond,
1991: The description of the Navy operational global atmospheric prediction
system's spectral forecast model. Mon. Wea. Rev., 119, 1786-1815.
Li, T., and T.F. Hogan, 1998: The role
of the annual mean climate on seasonal and interannual variability of the
tropical Pacific in a coupled GCM. J. Climate (in press).
Sadler, J.C., M.A. Lander, A.M. Hori,
and L.K. Oda, 1987: Tropical marine climatic atlas. Vol. 2: Pacific Ocean.
Report UHMET 87-02, Department of Meteorology, University of Hawaii, Honolulu,
Hawaii, 27 pp.
Top
CMIP Documentation Directory
Last update 15 May, 2002. This page is maintained by Tom Phillips
(phillips@pcmdi.llnl.gov).
LLNL Disclaimers
UCRL-MI-126431