GDCNTR draws contour lines through a scalar grid.
INPUT PARAMETERS
GDATTIM *Grid date/time
GLEVEL *Grid level
GVCORD *Grid vertical coordinate
GFUNC *Grid function
GDFILE *Grid file
CINT *Contour interval/min/max
LINE *Line color/type/width/label
MAP *Map color/dash/width
TITLE *Title color/line/title
DEVICE *Graphics device
PROJ *Map projection/angles/margins
GAREA *Graphics area
CLEAR *Clear screen flag
PANEL *Panel location/color/dash/width
TEXT *Text size/font/width/hw flag
SCALE *Scaling factor
LATLON *Line color/dash/width/label/inc
HILO *Color/sym/rng/rad/cnt/int?
HLSYM *HILO text size/font/width/hw flag
CONTUR *Contour attributes
SKIP *Skip factor
FINT *Fill interval/min/max
FLINE *Fill colors
CTYPE *Contour type: C/F
PROGRAM DESCRIPTION
GDCNTR draws contour lines through a scalar grid computed
using the GEMPAK grid diagnostic functions.
Contours may be displayed as lines or as a color fill.
If CTYPE is L (or C), contour lines are drawn using input
from CINT and LINE. If CTYPE is F, filled contours are
drawn using specifications from FINT and FLINE. Both contour
lines and filled contours are drawn if CTYPE is either
F/L or F/C.
The attributes of the contour lines, including the color,
line type, line width, and label frequency are specified
in LINE. The four attributes must be separated with slashes;
semicolons separate the values for each attribute. If the
line type is set to a single negative number, negative
contour values will have the absolute value of the line type
and positive values will be solid. If the label type is set
to a single number, n, then every nth value will be labelled.
The attributes of the color fill are specified in FLINE.
FINT specifies the interval or levels for the color fill.
The first color specified in FLINE fills values less than the
first level; while the last color fills values greater than
the last level. Hence, n levels require n+1 colors.
A range of colors may be specified in either FLINE or LINE by
specifying starting, ending and increment values in that order
separated by dashes. If the increment is missing, a default
of 1 is used.
The variables CINT and FINT specify contour interval,
minimum value, and maximum value separated with slashes. A
scaling factor may be entered in SCALE. The data in the grid file
will be multiplied by 10 ** SCALE. If no contour interval is
entered, a default value which will generate 5 to 10 contour
lines will be selected. The scaling will be done before the
contour interval is computed.
The SKIP parameter specifies the number of grid points to skip
in generating contours. For example, if SKIP = 1, every other
point is used to generate the contours.
The HILO and HLSYM parameters control marking and labeling the
values of relative maxima and minima.
A map, lat/lon grid, and title may also be included.
EXAMPLES
1. Draw contours every 4 degrees through the 850-mb
temperature field for the 24-h forecast time. Negative
values will be dashed using line type 3; every other
contour line will be labelled; all the contour lines will be
drawn in color number 1. The display area will be a Mercator
map centered on Colorado. The contours are drawn on a clear
screen with a dotted map, dotted lat/lon lines every 5 degrees
and no title.
GDATTIM = f24
GLEVEL = 850
GVCORD = pres
GFUNC = tmpc
GDFILE = ngm.grd
PROJ = mer
GAREA = co
LINE = 1/-3/1/2
CINT = 4
SCALE =
MAP = 1/10
LATLON = 1/10/1/1/5;5
TITLE = 0
DEVICE = xw
PANEL = 0
CLEAR = yes
TEXT =
CTYPE = l
2. Now overlay dewpoint lines on the above plot. The contour
interval is set to 5. The lines will be drawn dashed
using color number 2, with labelling and line types
as above. Only parameters which must be changed from the
above definitions are shown. The title "Temperature and
Dewpoint" is added in color 1.
GFUNC = dwpc
LINE = 2/-3/1/2
CINT = 5
CLEAR = no
MAP = 0
LATLON = 0
TITLE = 1//Temperature and Dewpoint
3. Now clear the screen and draw a color fill of the divergence
of the gridded wind, alternating between color 3 and 7.
Scale the data by 10**5 and use a default contour interval.
Draw contour lines in color 2 using heavy, solid lines,
labelling every contour level.
GFUNC = div (wnd)
CLEAR = yes
CINT =
SCALE = 5
LINE = 2/1/7/1
FINT =
FLINE = 3;7
MAP = 1
CTYPE = f/l
4. Clear the screen and draw contours of vorticity. Label
vorticity maxima with a red X and minima with a cyan N.
Plot the values of the extrema. Exclude minima less than
4 * 10 ** -5. The search radius for finding extrema is
5 grid points. Interpolate the extrema to off-grid point
locations. Plot the values in font number 2 on the
right beneath the marking symbol. Plot the marking label
in size 1.5, the values in size 1.
GFUNC = avor (wnd)
CLEAR = yes
CINT = 2
SCALE = 5
LINE = 2/-3/2
HILO = 2;6/X#;N#/;4-28/5//YES
HLSYM = 1.5;1/3/1;2
ERROR MESSAGES
[GDCNTR +1] WARNING. There are no contour levels.
[GDCNTR -1] Fatal error initializing TAE.
[GDCNTR -2] Fatal error reading TAE parameters.
[GDCNTR -3] Fatal error initializing GEMPLT.
[GDCNTR -4] Grid requested is not available.
[GDCNTR -5] Error setting grid navigation for file ....
[GDCNTR -6] There are no grids in grid file.