Sounding Station Parameters and Indices

SLATStation latitude in degrees
SLONStation longitude in degrees; West longitude is negative
SELVStation elevation in meters
SHOW Showalter index
SHOW= T500 - Tparcel
T500= Temperature in Celsius at 500 mb
Tparcel= Temperature in Celsius at 500 mb of a parcel lifted from 850 mb
LIFT Lifted index
LIFT= T500 - Tparcel
T500= temperature in Celsius of the environment at 500 mb
Tparcel= 500 mb temperature in Celsius of a lifted parcel with the average pressure, temperature, and dewpoint of the layer 500 m above the surface
LFTVLIFT computed by using virtual temperature.
SWET SWEAT index
SWET= 12 * TD850 + 20 * TERM2 + 2 * SKT850 + SKT500 + SHEAR
TD850 = Dewpoint in Celsius at 850 mb
TERM2 = MAX ( TOTL - 49, 0 )
TOTL = Total totals index
SKT850= 850 mb wind speed in knots
SKT500= 500 mb wind speed in knots
SHEAR = 125 * [ SIN ( DIR500 - DIR850 ) + .2 ]
DIR500= 500 mb wind direction
DIR850= 850 mb wind direction
KINX K index
KINX= ( T850 - T500 ) + TD850 - ( T700 - TD700 )
T850 = Temperature in Celsius at 850 mb
T500 = Temperature in Celsius at 500 mb
TD850 = Dewpoint in Celsius at 850 mb
T700 = Temperature in Celsius at 700 mb
TD700 = Dewpoint in Celsius at 700 mb
CTOT Cross Totals index
CTOT= TD850 - T500
TD850 = Dewpoint in Celsius at 850 mb
T500 = Temperature in Celsius at 500 mb
VTOT Vertical Totals index
VTOT= T850 - T500
T850= Temperature in Celsius at 850 mb
T500= Temperature in Celsius at 500 mb
TTOT Total Totals index
TOTL= ( T850 - T500 ) + ( TD850 - T500 )
T850 = Temperature in Celsius at 850 mb
TD850= Dewpoint in Celsius at 850 mb
T500 = Temperature in Celsius at 500 mb
CAPE Convective Available Potential Energy (J/kg)
CAPE= GRAVTY * SUMP ( DELZ * ( TP - TE ) / TE )
SUMP= sum over sounding layers from LFCT to EQLV for which ( TP - TE ) is greater than zero
DELZ= incremental depth
TP = temperature of a parcel from the lowest 500 m of the atmosphere, raised dry adiabatically to the LCL and moist adiabatically thereafter
TE = temperature of the environment
CAPVCAPE computed by using the virtual temperature.
CAPV= GRAVTY * SUMP ( DELZ * ( TVP - TVE ) / TVE )
SUMP= sum over sounding layers from LFCV to EQTV for which ( TVP - TVE ) is greater than zero
DELZ= incremental depth
TVP = virtual temperature of a parcel from the lowest 500 m of the atmosphere, raised dry adiabatically to the LCL and moist adiabatically thereafter
TVE = virtual temperature of the environment
CINS Convective Inhibition (J/kg)
CINS= GRAVTY * SUMN ( DELZ * ( TP - TE ) / TE )
SUMN= sum over sounding layers from top of the mixed layer to LFCT for which ( TP - TE ) is less than zero.
DELZ= incremental depth
TP = temperature of a parcel from the lowest 500 m of the atmosphere, raised dry adiabatically to the LCL and moist adiabatically thereafter
TE = temperature of the environment
CINVCINS computed by using the virtual temperature.
CINV= GRAVTY * SUMN ( DELZ * ( TVP - TVE ) / TVE )
SUMN= sum over sounding layers from top of the mixed layer to LFCV for which ( TVP - TVE ) is less than zero.
DELZ= incremental depth
TVP = virtual temperature of a parcel from the lowest 500 m of the atmosphere, raised dry adiabatically to the LCL and moist adiabatically thereafter
TVE = virtual temperature of the environment
EQLVEquilibrium level (hPa)
EQLV= level at which a parcel from the lowest 500 m of the atmosphere is raised dry adiabatically to the LCL and moist adiabatically to a level above which the temperature of the parcel is the same as the environment. If more than one Equilibrium Level exists, the highest one is chosen.
EQTVEQLV computed by using the virtual temperature.
LFCT Level of Free Convection (hPa) by comparing temperature between a parcel and the environment
LFCT= level at which a parcel from the lowest 500 m of the atmosphere is raised dry adiabatically to LCL and moist adiabatically to the level above which the parcel is positively buoyant. If more than one LFCT exists, the lowest level is chosen. If the parcel is positively bouyant throughout the sounding, the LFCT is set to be the same as the LCLP.
LFCVLFCT computed by using the virtual temperature.
BRCH Bulk Richardson number
BRCH= CAPE / ( 0.5 * U**2 )
CAPE = Convective Available Potential Energy
U = magnitude of shear ( u2 - u1, v2 - v1 )
u1,v1= average u,v in the lowest 500 m
u2,v2= average u,v in the lowest 6000 m
BRCVBRCH computed by using CAPV
BRCV= CAPV / ( 0.5 * U**2 )
CAPV = CAPE computed by using the virtual temperature.
U = magnitude of shear ( u2 - u1, v2 - v1 )
u1,v1= average u,v in the lowest 500 m
u2,v2= average u,v in the lowest 6000 m
LCLT Temperature (K) at the LCL, the lifting condensation level, from an average of the lowest 500 meters.
LCLT= [1 / ( 1 / ( DWPK - 56 ) + LN ( TMPK / DWPK ) / 800 )] + 56
LCLP Pressure (hPa) at the LCL, the lifting condensation level, from an average of the lowest 500 meters.
LCLP= PRES * ( LCLT / ( TMPC + 273.15 ) ) ** ( 1 / KAPPA )
Poisson's equation
MLTHMean mixed layer THTA (K)
MLTH= average THTA in the lowest 500 m
MLMRMean mixed layer MIXR (g/kg)
MLMR= average MIXR in the lowest 500 m
THTK1000 mb to 500 mb thickness (meter)
THTK= ( Z500 - Z1000 )
Z500 = Height of the 500 mb surface
Z1000= Height of the 1000 mb surface
PWAT Precipitable water (mm) for the entire sounding.