SFCCON

Contours surface hourly data from ISFC-schema point files.

Formats

SFCCON param map time day [keywords]
SFCCON par1-par2 map time1-time2 day1-day2 [keywords]

Parameters

param	parameter to contour; valid parameters are those defined in the SFCCON.CORE, SFCCON.SITE and SFCCON.USER files; see the Remarks for more information and a list of the parameters in SFCCON.CORE (default=T)
par1-par2	parameter difference to contour, e.g., T-TD for dewpoint depression; see the Remarks
map	map for the contour; see the MAP command for a list of valid predefined maps, for example, FL, MID, USA, WORL (default=do not draw a map; use the navigation of the frame specified with NAV keyword)
time	observation time; see the Remarks (default=current or most recent reporting hour)
time1-time2	time difference to contour, e.g., 12-6 to subtract 6 UTC data from 12 UTC data; see the Remarks
day	observation date; valid formats include YYYYDDD, YYYY/MM/DD, and DD/MON/YYYY where YYYY, DDD, MM, and DD are integers and MON is three or more letters, for example, JAN or JANUARY (default=current)
day1-day2	day difference to contour, e.g., 2000110-2000109 to subtract day 2000109 data from day 2000110 data; see the Remarks

Keywords

CHIlltype=	CURRENT		compute the wind chill values for the CHILL option using the formula implemented by the National Weather Service in November 2001 (default)
	OLD		compute the wind chill values using the pre-2001 formula
CINt=	num	contour interval; specify 0 to let SFCCON compute a reasonable interval; specify your own interval as an integer or decimal value greater than zero (default=from the CONTOUR.DEF text file; if no file entry matches the parameter and units, default=0)
	string	contour values; specify the name of a string that contains up to 64 values; e.g., CINT=SNOWDEPTH will draw contours at the values specified in the string named SNOWDEPTH
COLor=	graphics color level for the display (default=2)
DASh=	ALL	dash all contours
	NEG	dash negative contours only
	POS	dash positive contours only
DATaset=	ADDE point dataset name and position; specify as group/descriptor.position or alias.position where position is a positive integer (absolute position), 0 or a negative integer (relative position), or ALL (default=RTPTSRC/SFCHOURLY.ALL)
GRA=	graphic frame number for the display (default=current)
LSIze=	contour label height, in pixels (default=8)
NAV=	num	frame to use for navigation
	C	use the current frame's navigation (default)
	you cannot use the NAV keyword if you specify a map with the map parameter
PTYpe=	ALT	use altimeter setting when computing station pressure for use in the equations that generate the contoured values if the PSTN, MIX, THA or THAE option is specified (default); see the Remarks
	PMSL	use sea-level pressure when computing station pressure for use in the equations that generate the contoured values if the PSTN, MIX, THA or THAE option is specified
UNIt=	units for the specified parameter; see the Remarks for defaults; run the CU LIST command to list the valid units and abbreviations for the parameters that can be changed

Remarks

SFCCON builds and runs a PTCON command to display surface hourly data from ISFC-schema point files. SFCCON accepts all the keywords in the PTCON command except LAT, LON, MAP, PRO, SLAT, SLON and PARAM because they may conflict with SFCCON's parameters or keywords. You can use the PTCON SELECT keyword to limit the analysis to a specified list or range of values, but you cannot specify a different parameter, time, day or unit than those defined by the SFCCON parameters or keywords.

The table below lists the parameter name, default units and a description of each parameter defined in the SFCCON.CORE file. Default units enclosed in parenthesis cannot be changed. The .CORE file is supplied with McIDAS-X and should not be modified. The .USER file overrides the .SITE file, which overrides the .CORE file. This order of precedence allows you or your site to change existing parameters and/or add new parameters in your .USER or .SITE file. To create a .USER or .SITE file, copy the .CORE file from ~mcidas/data to your $HOME/mcidas/data directory (or another MCPATH directory), rename it, then edit the existing predefined parameters and/or add new ones.

param	Default Units	Description
ELEV	FT	station elevation
T	F	temperature
CHILL	(F)	wind chill index
HEAT	(F)	heat index
TD	F	dew point temperature
MIX	(G/KG)	mixing ratio
THA	(K)	potential temperature
THAE	(K)	equivalent potential temperature
DIR	(degrees)	wind direction
SPD	KTS	wind speed
GUS	KTS	wind gusts
STREAML		streamlines
ALTIM	MB	altimeter setting
PMSL	MB	sea-level pressure
PSTN	(MB)	station pressure
VIS	MI	visibility
PCP	IN	three- or six-hour precipitation total; three-hour total reported only at 3, 9, 15, 21 UTC; six-hour total reported only at 0, 6, 12, 18 UTC; see the Remarks
PCP3	IN	three-hour PCP total; reported only at 3, 9, 15, 21 UTC; see the Remarks
PCP6	IN	six-hour PCP total; reported only at 0, 6, 12, 18 UTC; see the Remarks
PCP24	IN	24-hour precipitation total; reported at 12 UTC; see the Remarks
SNO	IN	snow depth; reported only at 0, 6, 12, 18 UTC; see the Remarks
CAC	(code)	ceiling cloud amount; 0=clear, 5=few, 1=scattered, 2=broken, 3=overcast
CA1	(code)	first non-ceiling cloud amount; 0=clear, 5=few, 1=scattered, 2=broken, 3=overcast
CA2	(code)	second non-ceiling cloud amount; 0=clear, 5=few, 1=scattered, 2=broken, 3=overcast
CZC	FT	height of cloud ceiling
CZ1	FT	height of first non-ceiling cloud layer
CZ2	FT	height of second non-ceiling cloud layer
ABV	(sec^-1)	absolute vorticity
VOR	(sec^-1)	vorticity
DVG	(sec^-1)	divergence

The time default is the current hour for all parameters except PCP, PCP3, PCP6, PCP24 and SNO. Because PCP and SNO are not reported every hour in METAR reports, the default for these parameters is the most recent hour storing the data. PCP is reported every three hours starting at 0 UTC. PCP3 represents the three-hour totals in PCP; it is reported at 3, 9, 15, and 21 UTC. PCP6 represents the six-hour totals in PCP; it is reported at 0, 6, 12, and 18 UTC. PCP24 represents the 24-hour precipitation totals and is reported at 12 UTC only. SNO is reported every six hours at 0, 6, 12, and 18 UTC.

This means, for example, that the time default for PCP is 0 if the current time is between 0:00 and 2:59 UTC; the time default for PCP3 is 3 if the current time is between 3:00 and 8:59 UTC; the time default for SNO and PCP6 is 6 if the current time is between 6:00 and 11:59 UTC. The time default for PCP24 is 12 UTC today if the current time is between 12:00 and 23:59 UTC, and is 12 UTC yesterday if the current time is between 0:00 and 11:59 UTC.

Parameter advection or divergence is done by appending ADV or DVG to the parameter name, e.g., TADV and SPDDVG. Parameters with their default units enclosed in parenthesis in the table above (e.g., CHILL, MIX and THA) and advected or diverged parameters cannot be used with the differencing options (par1-par2, time1-time2 and day1-day2).

If you specify both a time difference (time1-time2) and a day difference (day1-day2), SFCCON contours the values equal to the parameter at time1,day1 minus the parameter at time2,day2. If you specify a parameter difference (par1-par2) with a time difference and day difference, SFCCON contours the values equal to the parameter difference at time1,day1 minus the parameter difference at time2,day2. For example,
SFCCON T-TD MID 0-12 2000123-2000122 contours the values equal to the dewpoint depression at 0UTC,day2000123 minus the dewpoint depression at 12UTC,day2000122.

In the PTYPE keyword, specify either PMSL or SLP for sea-level pressure, and ALT, ALTM or ALTIM for altimeter setting. The keyword is valid only with the calculated options that contain station pressure in their equations (PSTN, MIX, THA and THAE). Altimeter setting is the default because it's correct to use it (rather than sea-level pressure) when computing station pressure for use in the equations.

Examples

SFCCON

This entry contours the temperature for the current day and time using the navigation of the current frame.

SFCCON PCP3 UNIT=MM

This entry contours the most recent three-hour precipitation totals in millimeters using the navigation of the current frame. For example, if the current time is 19 UTC, the 15 UTC data is plotted since three-hour precipitation totals are reported only at 3, 9, 15 and 21 UTC.

SFCCON SNO MID 12 UNIT=CM COLOR=7 LABEL='12 UTC Midwest snow depth, in centimeters' 7 420 150

This entry contours snow depth in centimeters at 12 UTC over a map of the Midwest. The contours are drawn in graphics color level 7. The default label below the plot is replaced with the text 12 UTC Midwest snow depth, in centimeters near the center of the frame in graphics color level 7. LABEL is a PTCON keyword.

TE COLD "-20 -10 0 10 20 25 30 32 35

SFCCON T CINT=COLD DASH=NEG

The TE command creates a string called COLD containing contour values for the SFCCON entry. The SFCCON entry draws the -20, -10, 0, 10, 20, 25, 30, 32 and 35° Fahrenheit temperature contours for the current day and time using the navigation of the current frame. The -20° and -10° contours are dashed; the others are solid. Do not specify a pound sign (#) before the string name in the CINT keyword.

SFCCON PMSL NA 6 12/JAN/1996 DATASET=CLIMATE/1996

This entry contours sea-level pressure over a map of North America at 6 UTC on 12 January 1996 using the data in the dataset CLIMATE/1996.

SFCCON TDADV KY

This entry contours dewpoint temperature advection over a map of Kentucky.

SFCCON VIS MID 12-0 2000131-2000130

This entry contours the 36-hour visibility change from 0 UTC, day 2000130 to 12 UTC, day 2000131 over a map of the Midwest.

SFCCON THA USA PTYPE=PMSL

This entry calculates and contours potential temperature over a map of the United States for the current day and hour. Mean sea-level pressure is used when computing station pressure for use in the potential temperature calculation. This may yield some error in the values, with higher station elevations usually having larger errors.

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