SFCNTR plots surface station data on a map and optionally
       contours one of the fields being plotted.

INPUT PARAMETERS
 
    AREA      Data area
    GAREA     Graphics area
    SATFIL    Satellite image filename(s)
    RADFIL    Radar image filename(s)
    SFPARM    Surface parameter list
    DATTIM    Date/time
    SFFILE    Surface data file
    COLORS    Color list
    MAP       Map color/dash/width/filter flag
    LATLON    Line color/dash/width/label/inc
    TITLE     Title color/line/title
    CLEAR     Clear screen flag
    PANEL     Panel loc/color/dash/width/regn
    DEVICE    Device|name|x size;y size|color type
    PROJ      Map projection/angles/margins|drop flag
    FILTER    Filter data factor
    TEXT      Size/fnt/wdth/brdr/N-rot/just/hw flg
    LUTFIL    Enhancement lookup table filename
    STNPLT    Txtc/txt attr|marker attr|stnfil
    CLRBAR    Color/ornt/anch/x;y/ln;wd/freq
    CNTRPRM   Parameter to contour
    GAMMA     Convergence parameter
    WEIGHT    Barnes Weighting parameter
    LINE      Color/type/width/label/smth/fltr
    CONTUR    Subbox/smooth
    NPASS     Number of passes
    CINT      Contour interval/min/max
 
 

PROGRAM DESCRIPTION
 
    SFCNTR is a special version of SFMAP which optionally
    allows the user to select one of the parameters specified in
    SFPARM to be contoured using Barnes objective analysis.

    SFCNTR uses the mean station spacing as provided in OAGRID
    in order to define a suitable number of gridpoints for the
    analysis. Objective analysis is accomplished using the Barnes
    method as given in OABSFC. Finally, contours are drawn as in
    the GDCNTR program.

    SFMAP plots data at station locations on a map.  Any
    parameter that can be computed from the parameters in
    the data set can be displayed.  Conditions can be specified
    for the parameters.  The conditions are documented in the
    SFPARM documentation.  Data may be plotted in any
    valid GEMPAK projection and may be overlaid on images.

    A list of times may be given in DATTIM allowing animation of
    surface plots.

    The order of the input parameters determines their location
    on the plot.  Parameters are separated by semicolons.  A
    position may be skipped by entering two consecutive semicolons
    or entering the name SPAC or BLNK.  A parameter will be
    plotted centered at the station if it is the first parameter
    in the list, for example, if SFPARM = SKYC, the sky cover symbol
    will be plotted centered on the station location.  If no
    parameter is to be displayed centered on the station location,
    a semicolon must appear before the first parameter listed.
    SPAC or BLNK may also be entered.  The following chart shows
    the location on the model of each position.

				8
			2	10	4
			3	1	5
			6	11	7
				9

    Note that wind symbols and markers are always plotted at the center
    of the station model.

    If FILTER is set to YES, the stations will be filtered so that
    overlapping stations will not be plotted.  FILTER may also be
    entered as a number greater than or equal to zero.  FILTER = NO
    has the same effect as FILTER = 0.  FILTER = 1 has the same
    effect as FILTER = YES.  Values less than 1 allow more crowding
    of stations, values exceeding 1 less crowding.  If a position
    is skipped using two semicolons or if the parameter is BLNK, the
    filter will not allocate the space.  The parameter SPAC may be
    used to reserve the space with the filter option.  Then later
    plots will plot the same stations after filtering, provided
    that the same parameter locations are specified.

    If certain stations are not to be removed by the filter, these
    stations are listed first following an @.  The area over which
    filtering is to occur is specified after a slash.  For example,

			AREA   = @bwi;iad;dca/md
			FILTER = YES

    will display a filtered array of stations over the area
    corresponding to MD, but BWI, IAD and DCA will be shown
    regardless of the filtering.

    Weather symbols can also be plotted.  The size and width of
    the symbols can be specified by appending the numbers to the
    parameter name using a colon as a separator.  For example,
    WSYM:2:5 will plot weather symbols with size of 2. and line
    width of 5.

    Other symbols can be specified in a similar way.  The names for
    the pressure tendency, sky cover, cloud type, weather and wind
    symbols and how their characteristics are set are given in the
    SFPARM documentation.

    Parameters can be color-coded based on their own value or on
    the value of any other computable parameter.  Refer to the
    COLORS documentation for details.  If one or more parameters
    are color-coded, a color bar will be displayed for the first
    color-coded parameter.

    CNTRPRM is the name of one of the parameters specified in SFPARM
    which will be contoured from objective analysis of the data.
    The parameter must be one listed in SFPARM. If the used does not
    want the data values displayed, set COLOR=0 for that SFPARM value.

    GAMMA is the Barnes objective analysis convergence parameter.

    WEIGHT is the Barnes weighting parameter. Typical values range from 20 to 50
    A value of 20 is the default.

    LINE provides the settings for contour lines used in the display.

    CONTUR is the grid sub-box and number of smoothing passes used by the
    contouring algorithm.

    NPASS is the number of passes in the Barnes scheme.

    CINT is the contour interval for the display.

 
EXAMPLES
 
    1.  Plot the 12Z observerd surface temperatures (tmpf) on a US map and
        contour the data using a contour interval of 5 degrees.

	AREA	 =  dset
	GAREA	 =  nj
	SATFIL	 =
	RADFIL	 =
	SFPARM	 =  tmpf
	DATTIM	 =  1200
	SFFILE	 =  metar
	COLORS	 =  6
	MAP	 =  3/1/1
	LATLON	 =  0
	TITLE	 =  1
	CLEAR	 =  yes
	PANEL	 =  0
	DEVICE	 =  xw
	PROJ	 =  lcc
	FILTER	 =  n
	TEXT	 =  1/22//hw
	LUTFIL   =
	STNPLT   =
	CLRBAR   =
	CNTRPRM  =  tmpf
	GAMMA    =  .3
	WEIGHT   =  50
	LINE     =  5/1/1
	CONTUR   =  3/3
	NPASS    =  2
	CINT     =  5

ERROR MESSAGES
 
    [SFCNTR  -1]    Fatal error initializing TAE.
    [SFCNTR  -2]    Fatal error reading TAE parameters.
    [SFCNTR  -3]    Fatal error initializing GEMPLT.
    [SFCNTR  -4]    Parameter ... is not calculable.
    [SFCNTR  -5]    Winds are not calculable.