NCAR LSM Home Page

NCAR Land Surface Model (NCAR LSM version 1)

Model Availability

The NCAR LSM is available for all interested users. Please read the copyright notice and disclaimer .

The NCAR LSM package consists of 4 compressed tar files:

datasets.tar.Z = a sample NCAR LSM input data set
model.tar.Z = NCAR LSM source code
technote.tar.Z = postscript files for the NCAR technical note (model documentation and user's guide)
unix_scripts.tar.Z = Unix scripts to run the model and read history files

You can copy these tar files to your home system. If you are using "Netscape", click on the file name to save the file on your system.

The following text explains how these tar files were created, how to restore the NCAR LSM files, and how to run the model.

How to restore the NCAR LSM files

There are four directories ( datasets , model , technote , unix_scripts ) corresponding to the four tar files
Each directory has been tarred with the Unix command (using model as an example): tar cf model.tar model
Each tar file has been compressed with the Unix command (using model.tar as an example): compress model.tar
This creates the four compressed tar files: datasets.tar.Z , model.tar.Z , technote.tar.Z , unix_scripts.tar.Z
These files must be uncompressed with the Unix command (using model.tar.Z as an example): uncompress model.tar.Z
Each directory must be restored from its tar file with the Unix command (using model.tar as an example): tar xf model.tar

How to run the model on a workstation

The Unix script run_lsmv1.s, in the unix_scripts directory, will run the model for one day, using the sample input data set in the datasets directory and using a dummy atmospheric forcing. This script will have to be modified for your system and directory structure. I suggest you run this as an introduction to the model and its output.

Program Modules

SOIL TEMPERATURE
The NCAR LSM soil temperature subroutine calculates soil temperatures from one-dimensional thermal diffusion equation using apparent heat capacity to account for phase change. Soil temperature calculations depend on thermal conductivity for soil solids, thermal conductivity of dry soil, saturated volumetric soil water content of the soil, soil layer thickness, volumetric soil water content, specific heat capacity for soil solids, initial soil temperatures, heat flux into soil and snow depth at the surface.

SURFACE TEMPERATURES
The NCAR LSM surface temperature routine solves for vegetation and ground temperatures using the Newton-Raphson iteration. These temperatures must balance the surface energy budgets.

User inputs are:

pressure at agcm reference height (pa)
specific humidity at agcm reference height (kg/kg)
temperature at agcm reference height (kelvin)
atmospheric infrared (longwave) radiation (w/m**2)
wind speed in eastward direction (m/s)
wind speed in northward direction (m/s)
reference height for agcm (m)
thermal conductivity of snow/soil (w/m/kelvin)
wetted fraction of canopy
soil water evaporation factor (0 to 1)
soil water transpiration factor (0 to 1)
solar radiation absorbed by vegetation (w/m**2)
solar radiation absorbed by ground (w/m**2)
par absorbed per unit sunlit lai (w/m**2)
par absorbed per unit shaded lai (w/m**2)
true if random perturbation growth test
vegetation physiology type
soil temperature (kelvin)
time step (s)

Go To

NCAR Land Surface Model Homepage
Climate and Global Dynamics Division home page
Terrestrial Sciences Section home page
Climate System Model home page