CAPE_CIN: Calculation of CAPE and CIN

In aiRthermo: Atmospheric Thermodynamics and Visualization

Description

Taking into account the data obtained in a radiosonde, and after defining the initial values of the parcel, this function calculates the values of CAPE and CIN for the sounding.

Usage

CAPE_CIN(Ps, Ts, ws, deltaP = 5, P0 = NA, T0 = NA, w0 = NA, PlowTop = NA, 
precoolType = "none", doLog = 0, getLiftedBack = FALSE, upToTop = TRUE, 
checkBuoyancy = 0)

Arguments

Ps	Pressures (Pa) defining the sounding.
Ts	Temperatures (K) defining the sounding.
ws	Mixing ratios (kg/kg) defining the sounding.
deltaP	The width (Pa) of the layers used in the calculation of the numerical solution for the vertical evolution. A default value of 5 Pa is used. It must be positive.
P0	The initial pressure (Pa) for the parcel that is lifted (may be the lowest level of the sounding). Missing value is used by default.
T0	The initial temperature (K) of the parcel being lifted. Missing value is used by default.
w0	The initial mixing ratio (kg/kg) of the parcel being lifted.
PlowTop	If some layers must be averaged in the bottom of the sounding this argument provides the pressure (Pa) at the top of the layer that must be averaged in the bottom of the sounding. NA is used by default.
precoolType	If requested, an adiabatic or an isobaric precooling of the initial parcel is performed. "none" is used by default, but "adiabatic" and "isobaric" are also accepted.
doLog	Use logarithmic vertical interpolation between sounding levels if doLog=1. The default value is doLog=0.
getLiftedBack	TRUE/FALSE requests that the evolution of the lifted particle until the top level of the soundig is returned as a set of vectors for P, T and w (fields Pl, Tl and wl respectively). FALSE is used by default.
upToTop	TRUE(FALSE) requests that the lifted particle continues(stops) after the first crossing with the ambient sounding (EL) (until the sounding finishes). If TRUE, remaining negative areas above are accumulated into CIN only if the parcel becomes buoyant again in upper levels depending on the setting of checkBuoyancy. TRUE is used by default.
checkBuoyancy	If checkBuoyancy is TRUE, the computation of CAPE and CIN proceed to the top of the sounding if upToTop is TRUE if CAPE is larger than CIN while the parcel passes non-buoyant regions. The default value is FALSE.

Details

CAPE and CIN (J/kg) are calculated from a sounding given by 1D arrays for pressure Ps (Pa), for temperature Ts (K) and for mixing ratio ws (kg/kg).

If P_0/T_0/w_0 are provided, no low vertical averaging is done and these values are used as initial points for the parcel. Missing value is used by default for these arguments.

This function returns some error codes in field outCode in the return value if the computation of CAPE and CIN failed.

Value

Returns:

airStart	The real starting variable of the air parcel. It is a vector with 6 elements: P (Pa), Temp (K), w (kg/kg), theta (K), Tvirtual (K) and wsat (kg/kg). The values are computed depending on the input arguments.
cape	CAPE index (J/kg).
cin	CIN index (J/kg) as a negative number.
apLCL	Variables of the air parcel at the Lifting Condensation Level (LCL). It is returned as a vector with 6 elements: P (Pa), Temp (K), w (kg/kg), theta (K), virtualT (K) and wsat (kg/kg).
apLFC	Variables of the Level of Free Convection (LFC). If LFC is found, it is returned as a vector with six elements: P (Pa), Temp (K), w (kg/kg), theta (K), virtualT (K) and wsat (kg/kg).
apEL	End Level (EL). If EL is found, it is returned as a vector with six elements: P (Pa), Temp (K), w (kg/kg), theta (K), virtualT (K) and wsat (kg/kg).
gotLCL	TRUE/FALSE whether the LCL has been found or not.
gotLFC	TRUE/FALSE whether the LFC has been found or not.
gotEL	TRUE/FALSE whether the EL has been found or not.
Pl	Pressure (Pa) at every step of the lifted particle during its evolution. If requested by using getLiftedBack==TRUE, every step until the end of the radiosonde is returned.
Tl	Temp (K) at every step of the lifted particle during its evolution. If requested by using getLiftedBack==TRUE, every step until the end of the radiosonde is returned.
wl	Mixing-ratio of the lifted particle during its evolution. If requested by using getLiftedBack==TRUE, every step until the end of the radiosonde is returned.
Olifted	Number of elements in Pl/Tl/wl.
upToTop	Process the whole sounding even after finding the first "EL level".
outCode	The error code returned by the C routine that computes CAPE/CIN. If 0, everything has been OK!

Examples

data(RadiosondeA)
aPs<-RadiosondeA[,1]*100
aTs<-C2K(RadiosondeA[,3])
aws<-RadiosondeA[,6]/1000
capeCin<-CAPE_CIN(PlowTop=98000,precoolType="adiabatic",
                  Ps=aPs,Ts=aTs,ws=aws,doLog=0,deltaP=5,
                  getLiftedBack=TRUE,upToTop=TRUE)
print(min(capeCin$Tl))

pdf("stuve.pdf")
stuveA<-stuve_diagram(Pres = aPs/100,Temp=aTs-273.15)
lines(capeCin$Tl-273.15,capeCin$Pl/100,col="red",lwd=2)
dev.off()

Example output

[1] "The CIN and the CAPE were calculated."
[1] 147.6939
png 
  2 

aiRthermo documentation built on May 1, 2019, 9:24 p.m.