GDPLOT draws contour lines through a gridded scalar field, and
draws barbs or arrows for vector grids. It can present
any number of time periods. It can also produce any
number of contours or vectors on each frame.
INPUT PARAMETERS
GDFILE *Grid file
GDATTIM *Grid date/time
GLEVEL *!Grid level
GVCORD *!Grid vertical coordinate
PANEL *!Panel location/color/dash/width
SKIP *!Skip factor
SCALE *!Scaling factor
GFUNC *!Grid function
CTYPE *!Contour type: C/F
CONTUR *!Contour attributes
CINT *!Contour interval/min/max
LINE *!Line color/type/width/label
FINT *!Fill interval/min/max
FLINE *!Fill colors
HILO *!Color/sym/rng/rad/cnt/int?
HLSYM *!HILO txt size/posn/font/wdth/hw
CLRBAR *!Bar clr/ornt/anch/x;y/ln;wd/freq
GVECT *!Grid vector function
WIND *!Wind symbol/siz/wdth/typ/hdsz
REFVEC *!Size;y-loc;x-loc
TITLE *!Title color/line/title
TEXT *Text size/font/width/hw flag
CLEAR *Clear screen flag
GAREA *Graphics area
PROJ *Map projection/angles/margins
MAP *Map color/dash/width
LATLON *Line color/dash/width/label/inc
DEVICE *Graphics device
PROGRAM DESCRIPTION
GDPLOT draws contour lines through a scalar grid computed
using the GEMPAK grid diagnostic functions. Then it draws
a vector grid using wind barbs or arrows. It can present
any number of time periods. It can also produce any
number of contours or vectors on each frame.
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.
If M is entered in the wind symbol specification of WIND, winds
will be displayed in m/s, unless the KNOTV operator has been
specified in GVECT, in which case the winds will be displayed
in knots. If K is entered in WIND, the wind is displayed in
knots.
For contours, SKIP 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.
For vectors, SKIP specifies the number of points to skip in both
coordinate directions. For example, SKIP = /1 will display winds
at every other grid point. SKIP = /0 displays winds at every grid
point.
The HILO and HLSYM parameters control marking and labeling the
values of relative maxima and minima.
CLRBAR specifies a color bar to describe color fill contours.
A map, lat/lon grid, and title may also be included.
GDATTIM may be specified with a single time or a series of times in the
following forms:
ALL
FIRST
LAST
first-last
time1;time2;time3;time4;...
first-last-increment
GFUNC may contain exclamation points to delimit any number of sets of
contour specifications. GVECT may contain exclamation points to delimit
any number of sets of vector plot specifications.
GLEVEL, GVCORD, PANEL, SKIP, SCALE, GFUNC, CTYPE, CONTUR, CINT, TITLE,
LINE, FINT, FLINE, GVECT, WIND, REFVEC, HILO, and HLSYM may contain
exclamation points to delimit specifications for the plots specified in
GFUNC and GVECT. If any parameter contains more specifications than the
number of plots specified in GFUNC or GVECT, they will be ignored.
Positions between exclamation points may be left blank. A trailing
exclamation point will be treated as a blank. If there is no trailing
exclamation point, the last specification will be repeated for subsequent
plots.
EXAMPLES
The simple examples from GDWIND & GDCNTR can be executed by GDPLOT
without modification. The following examples demonstrate the more
advanced features of GDPLOT.
1. All of the plots specified in GDCNTR and GDWIND can be combined.
The spaces are added between exclamation points for readability.
GDATTIM = 910819/00f00;910819/00f24
GLEVEL = 850
GVCORD = pres
GFUNC = temp !dwpt !div(obs)!
GVECT = wnd !grad ( tmpc ) ! !kntv (wnd)
GDFILE = GEMDATA:hrcbob.grd
PROJ = mer
GAREA = co
LINE = 1/-3/1/2!2/-3/1/4 !2/1/7/1
CINT = 4 !5 !0
SCALE = ! !5 !/999
MAP = 1/10
LATLON = 1/10/1/1/5;5
TITLE = 0
DEVICE = xw
PANEL = ul !ul !ur !ul
CLEAR = yes
TEXT =
CTYPE = C !C !F/L
FINT =
FLINE = ! !3;7
WIND = bm1 !an7 ! !bk1
SKIP = /0 !/1
HILO = 1!4!2;27
HLSYM = 1
CLRBAR = ! !1 !
2. All of the plots from GDCNTR and GDWIND can be combined onto
separate panels, and may be displayed for all of the intervening
time periods.
GDATTIM = 910819/00f00-910819/00f24
GLEVEL = 850
GVCORD = pres
GFUNC = temp !dwpt !div(obs)!
GVECT = ! ! !wnd!grad (tmpc)!kntv (wnd)
GDFILE = GEMDATA:hrcbob.grd
PROJ = mer
GAREA = co
LINE = 1/-3/1/2!2/-3/1/4!2/1/7/1
CINT = 4 !5 !0
SCALE = ! !5 !/999!/5 !/999
MAP = 1/10
LATLON = 1/10/1/1/5;5
TITLE = 1//Temp!4//Dwpt!2//Div !1//Wnd!4//Grad!8//KntV
DEVICE = xw
PANEL = ul !ul !ur !b
CLEAR = yes
TEXT =
CTYPE = C !C !F/L
FINT =
FLINE = ! !3;7
WIND = ! ! !bm1!an4 !bk8
SKIP = ! ! !0 !1
HILO = 1!4!2;27
HLSYM = 1
CLRBAR = ! !1 !
ERROR MESSAGES
[GDPLOT +1] WARNING. There are no contour levels.
[GDPLOT -1] Fatal error initializing TAE.
[GDPLOT -2] Fatal error reading TAE parameters.
[GDPLOT -3] Fatal error initializing GEMPLT.
[GDPLOT -4] Grid requested is not available.
[GDPLOT -5] Error setting grid navigation for file ....
[GDPLOT -6] There are no grids in grid file.