CGCM1 GHG+A IS92a Data
Monthly data at Lat/Lon Gaussian Grid
Dataset Summary
Model:
CGCM1
Run:
GHG+A IS92a 1
Grid:
Lat/Lon Gaussian
Variable:
Total Cloud (fraction)
Years:
1980-2100
Months:
1-12
Selected region:
Global
Lower left corner: I1=1
J1=1
(0.00E, 87.16S)
Lower right corner: I2=97 J1=1
(0.00W, 87.16S)
Upper left corner: I1=1
J2=48 (0.00E, 87.16N)
Upper right corner: I2=97 J2=48 (0.00W, 87.16N)
Area dimensions: 97 grid cells (long.) x 48 grid cells (lat.)
Lon/Lat Gaussian 97x48 Grid
Grid size: 97 grid cells (long.) x 48 grid cells (lat.)
The model grid is uniform along the longitude with grid box size of 3.75° and nearly uniform along
the latitude (approx. 3.75°). The longitudes are numerated eastwards starting from the Greenwich
meridian (0, 3.75E, 7.5E, ..., 3.75W, 0). The global grid contains an additional longitude I=97,
identical to I=1. Note that if you select an area other than global, this additional longitude is removed
from the data.
The Gaussian latitudes are numerated from South to North.
The latitude values, from J=1 to J=48, are
87.16S,
57.52S,
27.83S,
1.86N,
31.54N,
61.23N,
83.48S,
53.81S,
24.12S,
5.57N,
35.26N,
64.94N,
79.78S,
50.10S,
20.41S,
9.28N,
38.97N,
68.65N,
76.07S,
46.39S,
16.70S,
12.99N,
42.68N,
72.36N,
72.36S,
42.68S,
12.99S,
16.70N,
46.39N,
76.07N,
68.65S,
38.97S,
9.28S,
20.41N,
50.10N,
79.78N,
64.94S,
35.26S,
5.57S,
24.12N,
53.81N,
83.48N,
61.23S,
31.54S,
1.86S,
27.83N,
57.52N,
87.16N.
The above lat./lon. coordinates correspond approximately to the centers of the grid boxes.
Data format
The uncompressed data are in ASCII format, containing for each time step a header followed by data
values. The equivalent FORTRAN statements used to write the data out for each time step are
WRITE(1,6000) (IHEAD(I),I=1,8)
6000 FORMAT(1X,A4,I10,1X,A4,5I10)
WRITE(1,6100) ((F(I,J),I=1,IHEAD(5)),J=1,IHEAD(6))
6100 FORMAT(1P6E12.5)
where
IHEAD(1)
is the type of the data (GRID),
IHEAD(2) is the time step (YYYYMM for monthly data),
IHEAD(3) is the variable label,
IHEAD(4)
is the level,
is the X-dimension of the data array (number of longitudes for lat/lon data),
IHEAD(6) is the Y-dimension of the data array (number of latitudes for lat/lon data),
IHEAD(7) is 0 for data at lon/lat grid, 1 for data at northern polar stereographic grid and 2 for data at
southern polar stereographic grid,
IHEAD(8) is packing density of the original binary data,
F(I,J)
is the data array.
IHEAD(5)
Below is an example of data on a global Gaussian 97x48 grid:
GRID
190001
ST
1
97
48
0
2
-2.09526e+01-2.14439e+01-2.18592e+01-2.22651e+01-2.27251e+01-2.31801e+01
-2.37241e+01-2.43102e+01-2.48074e+01-2.52175e+01-2.56584e+01-2.60705e+01
...
-3.29826e+01-3.31546e+01-3.30324e+01-3.26828e+01-3.21358e+01-3.17146e+01
-3.08259e+01-3.06257e+01-3.02818e+01-2.97412e+01-2.92532e+01-2.91706e+01
In this example, the very first data value -2.09526e+01 is for the grid point (I=1,J=1) which
corresponds to (0°E,87.16°S). The next value -2.14439e+01 is for the grid point (I=2,J=1) which
corresponds to (3.75°E,87.16°S). The next value is for (I=3,J=1)->(7.5°E,87.16°S), and so on, until
(I=97,J=1) which is the same value as (I=1,J=1) because of periodicity. After that, the values for the
second latitude follow starting with (I=1,J=2) for (0°E,83.48°S) and ending with (I=97,J=2), and so
on. The last value in the field -2.91706e+01 is for grid point (I=97,J=48) which corresponds to (0°E
87.16°N).