The source code is in the src/ subdirectory of the model root directory (modeldir), which is provided in the model download file.
The TIEGCM Open Source Academic Research License Agreement specifies the terms and restrictions under which the NCAR/UCAR grants permission to use the model, including the source code, for research, academic, and non-profit purposes.
A detailed flow diagram and calling tree of the source code structure is available in single and multi-page pdf files:
Warning
Some details of these flow charts may be out of date with respect to TIEGCM version 1.95
The TIEGCM can be configured for two spatial/temporal resolutions (use the modelres shell variable in the job script to set the model resolution):
The vertical coordinate lev, or Zp, is a log-pressure scale ln(p0/p), where p is pressure and p0 is a reference pressure. Fields are calculated at either “interface” levels (ilev), or at “midpoint” levels (lev) (see lev and ilev coordinate definitions below).
- At 5.0 degree horizontal, Zp at interfaces = -7 to +5 by 0.5
- At 2.5 degree horizontal, Zp at interfaces = -7 to +5 by 0.25
Note
To interpolate model fields to constant height surfaces, you should use geometric height, which is available on the 3d model grid as “ZG” on secondary histories.
The spatial coordinates at the 5-degree resolution are defined as follows:
double lon(lon) ;
lon:long_name = "geographic longitude (-west, +east)" ;
lon:units = "degrees_east" ;
lon = -180, -175, -170, -165, -160, -155, -150, -145, -140, -135, -130,
-125, -120, -115, -110, -105, -100, -95, -90, -85, -80, -75, -70, -65,
-60, -55, -50, -45, -40, -35, -30, -25, -20, -15, -10, -5, 0, 5, 10, 15,
20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105,
110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175 ;
double lat(lat) ;
lat:long_name = "geographic latitude (-south, +north)" ;
lat:units = "degrees_north" ;
lat = -87.5, -82.5, -77.5, -72.5, -67.5, -62.5, -57.5, -52.5, -47.5, -42.5,
-37.5, -32.5, -27.5, -22.5, -17.5, -12.5, -7.5, -2.5, 2.5, 7.5, 12.5,
17.5, 22.5, 27.5, 32.5, 37.5, 42.5, 47.5, 52.5, 57.5, 62.5, 67.5, 72.5,
77.5, 82.5, 87.5 ;
double lev(lev) ;
lev:long_name = "midpoint levels" ;
lev:short_name = "ln(p0/p)" ;
lev:units = "" ;
lev:positive = "up" ;
lev:standard_name = "atmosphere_ln_pressure_coordinate" ;
lev:formula_terms = "p0: p0 lev: lev" ;
lev:formula = "p(k) = p0 * exp(-lev(k))" ;
lev = -6.75, -6.25, -5.75, -5.25, -4.75, -4.25, -3.75, -3.25, -2.75, -2.25,
-1.75, -1.25, -0.75, -0.25, 0.25, 0.75, 1.25, 1.75, 2.25, 2.75, 3.25,
3.75, 4.25, 4.75, 5.25, 5.75, 6.25, 6.75, 7.25 ;
double ilev(ilev) ;
ilev:long_name = "interface levels" ;
ilev:short_name = "ln(p0/p)" ;
ilev:units = "" ;
ilev:positive = "up" ;
ilev:standard_name = "atmosphere_ln_pressure_coordinate" ;
ilev:formula_terms = "p0: p0 lev: ilev" ;
ilev:formula = "p(k) = p0 * exp(-ilev(k))" ;
ilev = -7, -6.5, -6, -5.5, -5, -4.5, -4, -3.5, -3, -2.5, -2, -1.5, -1, -0.5,
0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7 ;
Note
The 2.5 degree configuration (“double-resolution”), is not fully tuned and validated in TIEGCM version 1.95.
As a community user, student, research scientist or developer, you may need to modify the model source code. It is best to do this after building and at least making a default execution of the model (see the QuickStart Section). To change one or more source files, simply go to the src/ subdirectory in the model root directory modeldir, and edit the files as necessary. Then return to the working directory workdir and re-execute the job script. It will recompile the modified files, and any other source files that depend on the modified files, and re-execute the model. Alternatively, you can enter the execution directory execdir, and recompile the code by typing “gmake” on the command line, then return to the working directory and re-execute the job script.