Welcome to the
SCAM Home Page
The NCAR Single-column Community
Atmosphere
Model
What is SCAM2?
The SCAM is a one-dimensional time-dependent version of the NCAR Community
Atmosphere Model, often referred to as a Single Column Model (SCM). A single
column model will predict the local time-rate-of-change of the large-scale
state variables (e.g., temperature, moisture, momentum, cloud water, etc.)
using specified horizontal flux divergences, a specified vertical motion
field (from which the large-scale vertical advection terms are evaluated),
and subgrid-scale sources, sinks and eddy transports. The subgrid-scale
contributions are determined by an arbitrary collection of user-selected
subgrid-scale physics parameterizations.
SCAM-2 is the latest version of the NCAR Single Column Model based on
its 3D global climate
model CAM2. Previous versions of the single column model based
on older releases of the global model are no longer being maintained although
they can still be downloaded from www.cgd.ucar.edu/cms/sccm/sccm.html.
This software distribution will build a single column version of the
CAM2.0
model released on May 17, 2002. The single column framework was redesigned to use much of the original CAM2 code and data structures as possible.
Therefore all physics parameterizations and surface components are identical
in coding structure to their respective counterparts in the 3D global model
making it trivial to migrate components between the two modeling frameworks.
The overall design includes the provision of a graphical user interface
(GUI) to the model. The point-and-click graphical interface streamlines
the control of code flow including: dataset selection; column location
(latitude/longitude) selection; modification of control variables (such
as termination conditions, update frequencies, specification of history
data, etc.); modification of initial data and the associated large-scale
forcing (e.g., modification of vertical structures, amplitudes, etc.);
and the visualization of output data (vertical profiles, time series, etc.).
In particular, we have emphasized a tight coupling of interactive graphical
analysis capabilities with the integration component of the model.
Presently only Eulerian vertical advection capabilities have been incorporated
into the modeling framework.
Like its 3D counterpart SCAM-2 uses many of the same netCDF
formatted boundary datasets. In addition to using CAM2-generated initial
and boundary condition datasets the modeling framework has been constructed
to incorporate data (e.g., initial conditions and forcing terms) as diagnosed
from various field experiments. The current standard "library" of field
program forcing/budget data includes GATE,
TOGA
COARE, and ARM IOP datasets. These
initial condition and forcing data are dynamically specifiable from the
GUI, as are global initial conditions and steady-state vertical motion
forcing data from ECMWF analyses and CCM climate integrations. The IOP
data serves a dual role by providing the necessary boundary forcing for
the one-dimensional model, and providing validation data for the time-dependent
solutions generated by the collection of physical parameterizations which
are being evaluated.
This modeling framework has been under development for several years,
with support from the Computer Hardware Advanced Mathematics Model Physics
(CHAMMP) Program, currently known as the Climate Change Prediction Program
(CCPP), which is administered by the Office of Energy Research under the
Office of Health and Environmental Research in the Department of Energy
Environmental Sciences Division. During this development period we have
been systematically evaluating the strengths and weaknesses of an SCM approach
(a manuscript is in preparation). Despite certain limitations, it has proven
to be an economical numerical experimentation environment for facilitating
the investigation and improvement of parameterizations of radiative and
moist processes in atmospheric general circulation models. We believe that
the current code distribution is sufficiently stable so that the community
will be able to build and execute the code in any of the common UNIX environments
to which is has been ported: currently supported systems are Sun/Solaris,
IBM RS6000/AIX, SGI/IRIX64, and Intel PC/Linux. in the near future.
The code is an UNSUPPORTED contribution to the university modeling community,
although we do wish to receive feedback on any problems users may encounter
(scam@ucar.edu). Users are strongly
encouraged to register their use of SCAM so that they may automatically
receive notification of program updates, new dataset availability, etc.
Users may register by sending email to scam@ucar.edu
with the subject "registration."
!!! Bulletins !!!
-
SCAM-2 is available for downloading. See Release
History for changes from previous versions.
Known Problems and Bugs
-
Having too few colors available on your display can result in scam crashing
when trying to post-plot data (due to a bug in some versions of NCAR graphics).
This can occur if you are simultaneously running Netscape (a notorious
color-map hog) or any application that uses a large number of colors and
your screen is using 8 bit color.
-
Some versions of netCDF libraries have a bug in them that causes scam to
crash itself during model initialization. This only occurs when the model
is *not* compiled statically, so the fix is to specify static compilation
during the configuration stage (this is the default).
Release History
SCAM Source Code, GUI, and Dataset Distribution
The graphical user interface (GUI) is only available as a precompiled binary
so you must download the correct version for your system and compiler.
This distribution contains all of the datasets required to run SCAM, including
three basic IOP datasets from GATE, TOGA, and ARM observations.
IOP Dataset Descriptions
The following is a description of the datasets included in the scam
distribution.
ARM
-
Download the latest ARM IOP dataset arm0795v1.2.nc.
This dataset is derived from observations made at the ARM site in Oklahoma
from July 18 to August 4, 1995. The observational data was subjected
to a variational analysis procedure at SUNY-Stonybrook, and subsequently
interpolated (using cubic spline interpolation) to 20 minute intervals
to be consistent with the standard CCM dynamical time step. Changes from
v1.0 include fixing some small negative values in some fields (namely Prec,
lowcld, midcld, hghcld, and totcld) that were caused by the interpolation
scheme. Changes from v1.1 include fixing a units conversion error in the
Q1 and Q2 fields, and modification of the vertical advection terms to add
an energy conversion term for use in 3D forcing. Note that none of the
changed fields are used to force the model (except for the vertical advection
terms), so the same results should be obtained as with the previous versions.
-
A version that contains only the data on the original observation timepoints
(3 hour), arm0795v1.2.3hour.nc,
is also available.
-
You can find the original data in ascii format here.
GATE
-
Download the latest GATE IOP dataset gate0874v1.2.nc.
This dataset contains data from observations made at the GATE site in the
Atlantic off the west coast of Senegal from August 30 to September 19,
1974. The original data was interpolated (using cubic spline interpolation)
to 20 minute intervals to be consistent with the standard CCM dynamical
time step. Changes from v1.0 include fixing the Q1 and Q2 fields which
had been put into incorrect units. Note that neither of the changed fields
are used to force the model, so the same results should be obtained as
with the previous version.
-
A version that contains only the data on the original observation timepoints
(3 hour), gate0874v1.2.3hour.nc,
is also available.
-
You can find the original data in ascii format here.
TOGA
-
Download the latest GCSS IOP dataset gcss1292v1.2.nc.
This dataset contains data from observations made over the TOGA IFA in
the tropical west Pacific from December 20, 1992 to December 27, 1992.
The original data has been interpolated (using cubic spline interpolation)
to 20 minute intervals to be consistent with the standard dynamical time
step in the CCM.
-
A version that contains only the data on the original observation timepoints
(6 hour), gcss1292v1.2.6hour.nc,
is also available.
-
You can find the original data in ascii format here.
Patches
There are none at this time.
Related Sites
NCAR Community Climate Models
Single Column
Modeling Home Page
Send email to:
scam@ucar.edu
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Page last modified February 4, 2003