GEMPAK Manual |
Programs | Parameters
SNPARM
SNPARM is a list of upper air parameters to be used in an upper-air
program.
The four-character parameter names must be separated by semicolons.
For example:
SNPARM = PRES;TMPC;DWPC;THTA
If a parameter is not present in a data set, the program will attempt
to derive it from those parameters which are present. For example,
if pressure, temperature and dewpoint are present in a data set,
then relative humidity can be derived.
In plotting programs, the position of the parameter determines
where it will appear with respect to the station location.
The first position is centered on the station. The other
positions are shown below:
8
2 10 4
3 1 5
6 11 7
9
In the example above, DWPC is plotted in position 3.
The layer parameters are computed over a default layer between the
specified level and the next level upward in the sounding. The depth
of the layer for layer averages may be specified preceded by ! in the
user input. The shear and RICH calculations can be done relative to
a direction by specifying the direction preceded by $ in the user input.
In-line functions can be used to modify/qualify the output parameters.
These functions are applied in the order given; however, arithmetic
operators must precede other operators. The function symbols must
precede the qualifying value and are defined as follows:
* multiply = equal to
/ divide $ direction
+ add % vertical coordinate
- subtract ! depth
< less than or equal to
> greater than or equal to
In the case of wind symbols, the size, line width, type and headsiz
(arrows) for drawing the symbol may be specified following a colon
after the symbol name and after the function specifications if any
exist. The drawing attributes are separated by colons. The type
is a three-digit number, ABC, interpreted digit by digit as follows:
A B C
1 = plot calm wind 1 = start at stn 1 = not filled
2 = ignore calm wind 2 = center at stn 2 = filled
3 = start on sky symbol 3 = not filled with box
4 = filled with box
Calm winds are plotted as a circle or an arrowhead for barbs and
arrows, respectively. Arrowheads and 50-unit barb flags are filled
if C=2 or 4. A box is plotted with background color if C = 3 or 4.
For example, if TYPE=122, a barb will be plotted as a circle if the
wind is calm; it will be centered on the station location, and 50-unit
flags will be filled. The default is 111.
Aliases were created to make it easier for the user to plot typical
sounding data by using pre-set parameters and colors. To use an
alias, enter the alias name for SNPARM and leave COLORS blank. If the
user does not leave COLORS blank, the selected colors will be used
instead of the pre-set alias colors.
See PRMLST.TBL for a list of current aliases for sounding data.
The GEMPAK sounding parameters and the corresponding four-character
abbreviations are:
TEMPERATURES
TMPC - Temperature in Celsius
TMPF - Temperature in Fahrenheit
TMPK - Temperature in Kelvin
THTA - Potential temperature in Kelvin
THTE - Equivalent potential temperature in Kelvin
THTS - Saturation equiv. pot. temp. in Kelvin
THTV - Virtual potential temperature in Kelvin
TVRK - Virtual temperature in Kelvin
TVRC - Virtual temperature in Celsius
TVRF - Virtual temperature in Fahrenheit
MOISTURE PARAMETERS
DWPC - Dewpoint in Celsius
DWPF - Dewpoint in Fahrenheit
DWPK - Dewpoint in Kelvin
DPDC - Dewpoint depression in Celsius
DPDF - Dewpoint depression in Fahrenheit
DPDK - Dewpoint depression in Kelvin
DPDX - Dewpoint depression in Celsius; if .ge. 30 plotted as an "X"
MIXR - Mixing ratio in g/kg
MIXS - Saturation mixing ratio in g/kg
PWTR - Precipitable water (mm) up to the specified level
RELH - Relative humidity in percent
TMWK - Wet bulb temperature in Kelvin
TMWC - Wet bulb temperature in Celsius
THWC - Wet bulb potential temperature in Celsius
TMWF - Wet bulb temperature in Fahrenheit
VAPR - Vapor pressure in millibars
VAPS - Saturation vapor pressure in millibars
LHVP - Latent heat of vaporization in J/kg
HEIGHT
HGHT - Height in meters
HGTM - Height in meters (alternate name)
HGTK - Height in kilometers
HGTD - Height in decameters
HGFT - Height in feet
HGFH - Height in hundreds of feet
HGFK - Height in thousands of feet
HGML - Height in miles
STDZ - Character standard height convention used on upper air charts
RSTZ - Numeric standard height convention used on upper air charts
DHGT - Dry hydrostatic height in meters
MHGT - Moist hydrostatic height in meters
PRESSURE AND ALTIMETER
PRES - Station pressure in millibars
PMSL - Mean sea level pressure in millibars
ALTI - Altimeter setting in inches from PRES
WINDS
ARRW - Wind arrow (m/s)
ARRM - Wind arrow (m/s)
ARRK - Wind arrow (knots)
BARB - Wind barb (m/s)
BRBM - Wind barb (m/s)
BRBK - Wind barb (knots)
DARR - Wind direction arrows of uniform length
UWND - U component of the wind in meters/second
VWND - V component of the wind in meters/second
UKNT - U component of the wind in knots
VKNT - V component of the wind in knots
DRCT - Wind direction in degrees
SPED - Wind speed in meters/second
SKNT - Wind speed in knots
PSPD - Packed speed and direction (ddfff) in meters/second
PKNT - Packed speed and direction (ddfff) in knots
WCMP - Wind component toward a specific direction
WNML - Wind component toward 90 deg from a specific direction
LIFTED CONDENSATION LEVEL
TLCL - Temperature in Kelvin of parcel raised to LCL
PLCL - Pressure in millibars of parcel raised to LCL
STABILITY INDICES
Note: Default depths are enclosed in parentheses.
SHOW - Showalter Index
LIFT - Lifted Index (100 mb)
LFTV - LIFT computed by using virtual temperature
SWET - Sweat Index
KINX - K Index
CTOT - Cross Totals Index
VTOT - Vertical Totals Index
TOTL - Total Totals Index
CAPE - Convective Available Potential Energy (500 m)
CAPV - CAPE computed by using virtual temperature
CINS - Convective Inhibition (500 m)
CINV - CINS computed by using virtual temperature
EQLV - Equilibrium Level (500 m)
EQTV - EQLV computed by using virtual temperature
LFCT - Level of Free Convection
LFCV - LFCT computed by using virtual temperature
BRCH - Bulk Richardson Number (500 m, 6000 m)
BRCV - BRCH computed by using CAPV
MLTH - Mixed layer mean potential temperature (500 m)
MLMR - Mixed layer mean mixing ratio (500 m)
LCLT - Temperature in Kelvin of the LCL
LCLP - Pressure in millibars of the LCL
PWAT - Precipitable water (mm) for the whole sounding
LAYER QUANTITIES
Note: Default depths are the layer depths in the sounding
except for SEPA for which the layer depth is 5 K.
RICH - Richardson number
BVFQ - Brunt-Vaisala frequency
BVSQ - Brunt-Vaisala frequency squared
BVPD - Brunt-Vaisala period
LAPS - Temperature lapse rate
STAB - Potential temperature lapse rate
STAP - Stability with respect to pressure in k/mb
SHRM - Wind shear magnitude
SHRD - Wind shear direction
SEPA - Vertical separation in mb between isentropes
STATION VARIABLES
STID - Character station identifier
STNM - 5-digit station identifier
SLAT - Station latitude in degrees
SLON - Station longitude in degrees, West is negative
SELV - Station elevation in meters
RANG - Range (specialized data)
AZIM - Azimuth (specialized data)
LATI - Latitude in degrees
LONG - Longitude in degrees, West is negative
DELT - Delta time (specialized data)
MISCELLANEOUS
DDEN - Density of dry air in kg/(m**3)
PSYM - Montgomery stream function
MARK - Markers
TEXT - Undecoded data
LHAN - Low level Haines Index
MHAN - Middle level Haines Index
HHAN - High level Haines Index
SPACING
SPAC - Plot a space, accounted for in FILTER
BLNK - Plot a blank, not accounted for in FILTER