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.