Level Layer Conversion
EFFECTIVE_LAYER_TP
NAME:
Effective_Layer_TP
PURPOSE:
Function to calculate the effective atmospheric layer temperature and
pressure by weighting level values with the integrated layer density.
CALLING SEQUENCE:
Error_Status = Effective_Layer_TP( Height, & ! Input
Pressure, & ! Input
Temperature, & ! Input
Water_Vapor_Pressure, & ! Input
Effective_Pressure, & ! Output
Effective_Temperature, & ! Output
RCS_Id =RCS_Id, & ! Revision control
Message_Log=Message_Log ) ! Error messaging
INPUT ARGUMENTS:
Height: Heights of the atmospheric levels.
UNITS: metres, m
TYPE: REAL(fp)
DIMENSION: Rank-1 (N x 1, where N>1)
ATTRIBUTES: INTENT(IN)
Pressure: Pressure of the atmospheric levels.
UNITS: hectoPascals, hPa
TYPE: REAL(fp)
DIMENSION: Same as Height
ATTRIBUTES: INTENT(IN)
Temperature: Temperature of the atmospheric levels.
UNITS: Kelvin, K
TYPE: REAL(fp)
DIMENSION: Same as Height
ATTRIBUTES: INTENT(IN)
Water_Vapor_Pressure: Water vapor partial pressure at the atmospheric levels
UNITS: hectoPascals, hPa
TYPE: REAL(fp)
DIMENSION: Same as Height
ATTRIBUTES: INTENT(IN)
OPTIONAL INPUT ARGUMENTS:
Message_Log: Character string specifying a filename in which any
Messages will be logged. If not specified, or if an
error occurs opening the log file, the default action
is to output Messages to standard output.
UNITS: N/A
TYPE: CHARACTER(*)
DIMENSION: Scalar
ATTRIBUTES: INTENT(IN), OPTIONAL
OUTPUT ARGUMENTS:
Effective_Pressure: Effective layer pressure.
UNITS: hectoPascals, hPa
TYPE: REAL(fp)
DIMENSION: Rank-1 (N-1 x 1)
ATTRIBUTES: INTENT(OUT)
Effective_Temperature: Effective layer temperature.
UNITS: Kelvin, K
TYPE: REAL(fp)
DIMENSION: Same as Effective_Pressure
ATTRIBUTES: INTENT(OUT)
OPTIONAL OUTPUT ARGUMENTS:
RCS_Id: Character string containing the Revision Control
System Id field for the module.
UNITS: N/A
TYPE: CHARACTER(*)
DIMENSION: Scalar
ATTRIBUTES: INTENT(OUT), OPTIONAL
FUNCTION RESULT:
Error_Status: The return value is an integer defining the error status.
The error codes are defined in the ERROR_HANDLER module.
If == SUCCESS the calculation was successful
== FAILURE an unrecoverable error occurred
UNITS: N/A
TYPE: INTEGER
DIMENSION: Scalar
PROCEDURE:
Based on:
Gallery, W.O., F.X. Kneizys, and S.A. Clough, "Air mass computer
program for atmospheric transmittance/radiance calculation: FSCATM",
AFGL-TR-83-0065, 9 March 1983.
The effective pressure and temperature is defined as,
__
\
> p.rho.dz
/__
_
p = ----------------- ..............................................(1)
__
\
> rho.dz
/__
and
__
\
> T.rho.dz
/__
_
T = ----------------- ..............................................(2)
__
\
> rho.dz
/__
where dz == layer thickness.
Note that the denominators of eqns(1) and (2) can also be referred to as the
column density.
The pressure and total density are both assumed to follow an exponential
profile with scale heights H_p and H_rho respectively. For a single layer
the numerator of eqn(1) can be written as,
__ k
\ H_p.H_rho
> p.rho.dz = ------------- ( p(k-1).rho(k-1) - p(k).rho(k) ) .....(3)
/__ H_p + H_rho
k-1
Similarly for the numerator of eqn(2) using the ideal gas law,
p = R_air.rho.T, we get
__ k
\ H_p
> T.rho.dz = -------( p(l-1) - p(l) ) ............................(4)
/__ R_air
k-1
and the denominator is given by,
__ k
\
> rho.dz = H_rho ( rho(l-1) - rho(l) ) ...........................(5)
/__
k-1
where the scale heights are defined as,
-( z(l) - z(l-1 ) )
H_p = --------------------- ........................................(6)
ln( p(l) / p(l-1) )
and
-( z(l) - z(l-1 ) )
H_rho = ------------------------- ..................................(7)
ln( rho(l) / rho(l-1) )
Note that in eqn.(4) the gas constant is that for *air*, not *dry air*. To
determine this the effective molecular weight of air (as a function of pressure)
must be determined.
Breaking down the units of the components,
units(p) = hPa
= 100 Pa
= 100 N.m^-2
= 100 kg.m.s^-2.m^-2
= 100 kg.m^-1.s^-2
m2
units(eqn(3)) = ----( 100 kg.m^-1.s^-2 . kg.m^-3 )
m
= 100 kg^2.m^-3.s^-2
m . 100 kg.m^-1.s^-2
units(eqn(4)) = -----------------------
J.g^-1.K^-1
m . 100 kg.m^-1.s^-2
= ------------------------
kg.m^2.s^-2.g^-1.K^-1
= 100 K.g.m^-2
= 0.1 K.kg.m^-2
units(eqn(5)) = m . kg.m^-3
= kg.m^-2
So the units of the final equations are:
_ units(eqn(3))
units(p) = ---------------
units(eqn(5))
100 kg^2.m^-3.s^-2
= --------------------
kg.m^-2
= 100 kg.m^-1.s^-2
= 100 kg.m.s^-2.m^-2
= 100 N.m^-2
= 100 Pa
= hPa
_ units(eqn(4))
units(T) = ---------------
units(eqn(5))
0.1 K.kg.m^-2
= ---------------
kg.m^-2
= 0.1 K
So the final temperatures must be multiplied by 0.1 to get units of K.
Note for the above units breakdown of eqn(4) that the gas constant
for air is computed in units of J.g^-1.K^-1, *NOT* the SI units of
J.kg^-1.K^-1. This is done solely to save the conversion operation
of g->kg for each loop iteration. Otherwise, for a gas constant in
units of J.kg^-1.K^-1, the final scaling factor for the effective
temperature would be 100, not 0.1.
CREATION HISTORY:
Written by: Paul van Delst, CIMSS/SSEC, 03-May-2000
paul.vandelst@ssec.wisc.edu
CREATE_SUBLEVELS
NAME:
Create_Sublevels
PURPOSE:
Function to create the sublevels used to integrate input profiles
to obtain average layer quantities. This routine is called before
Integrate_Sublevels.
Adapted from the UMBC INTLEV.F function supplied with the AIRS RTA.
CALLING SEQUENCE:
Error_Status = Create_Sublevels( Level_Pressure, & ! Input
Level_Temperature, & ! Input
Level_Absorber, & ! Input
n_Per_Layer, & ! Input
Sublevel_Pressure, & ! Output
Sublevel_Temperature, & ! Output
Sublevel_Absorber, & ! Output
RCS_Id =RCS_Id, & ! Revision control
Message_Log=Message_Log ) ! Error messaging
INPUT ARGUMENTS:
Level_Pressure: Pressure of the atmospheric levels.
UNITS: hectoPascals, hPa
TYPE: REAL(fp)
DIMENSION: Rank-1 (K)
K == number of levels
ATTRIBUTES: INTENT(IN)
Level_Temperature: Temperature of the atmospheric levels.
UNITS: Kelvin, K
TYPE: REAL(fp)
DIMENSION: Same as Level_Pressure
ATTRIBUTES: INTENT(IN)
Level_Absorber: Absorber concentrations at the atmospheric levels
UNITS: Doesn't matter - as long as they are
LEVEL specific.
TYPE: REAL(fp)
DIMENSION: Rank-2 (K x J)
K == number of levels
J == number of absorbers
ATTRIBUTES: INTENT(IN)
n_Per_Layer: Number of sublevels to create in each layer.
Value must be > or = 1.
UNITS: N/A
TYPE: INTEGER
DIMENSION: Scalar
ATTRIBUTES: INTENT(IN)
OPTIONAL INPUT ARGUMENTS:
Message_Log: Character string specifying a filename
in which any Messages will be logged.
If not specified, or if an error occurs
opening the log file, the default action
is to output Messages to standard output.
UNITS: N/A
TYPE: CHARACTER(*)
DIMENSION: Scalar
ATTRIBUTES: INTENT(IN), OPTIONAL
OUTPUT ARGUMENTS:
Sublevel_Pressure: Pressure of the atmospheric sublevels.
UNITS: hectoPascals, hPa
TYPE: REAL(fp)
DIMENSION: Rank-1 (Ks)
Ks == number of sublevels
== ( (K-1) * n_Per_Layer ) + 1
ATTRIBUTES: INTENT(IN)
Sublevel_Temperature: Temperature of the atmospheric sublevels.
UNITS: Kelvin, K
TYPE: REAL(fp)
DIMENSION: Same as output Sublevel_Pressure argument
ATTRIBUTES: INTENT(IN)
Sublevel_Absorber: Absorber concentrations at the atmospheric Levels
UNITS: Same as input
TYPE: REAL(fp)
DIMENSION: Rank-2 (Ks x J)
Ks == number of sublevels
J == number of absorbers
ATTRIBUTES: INTENT(IN)
OPTIONAL OUTPUT ARGUMENTS:
RCS_Id: Character string containing the Revision Control
System Id field for the module.
UNITS: N/A
TYPE: CHARACTER(*)
DIMENSION: Scalar
ATTRIBUTES: INTENT(OUT), OPTIONAL
FUNCTION RESULT:
Error_Status: The return value is an integer defining the error
status. The error codes are defined in the
ERROR_HANDLER module.
If == SUCCESS the calculation was successful
== FAILURE an unrecoverable error occurred
UNITS: N/A
TYPE: INTEGER
DIMENSION: Scalar
PROCEDURE:
The assumption is made that temperature and absorber amount vary
linearly with ln(p). To improve the quadrature in integrating Level
amounts to a layer value, each input layer, k, is split into N(k)
sublayers equally spaced in ln(p),
ln(p[k+1]) - ln(p[k]
ln(p[n+1]) - ln(p[n] = ---------------------
N(k)
given the pressures, p(1) - p(K) of the input Levels.
Once the sublevels are defined, the level temperatures and absorber
amounts are linearly interpolated at the specific number of sublevels
and those interpolates are associated with the sublevel pressures.
The last corresponding level/sublevel is assigned explicitly.
Currently, N is independent of k. That is, the same number of sublevels
are created for each layer.
CREATION HISTORY:
Written by: Paul van Delst, CIMSS/SSEC 19-Jan-2001
paul.vandelst@ssec.wisc.edu
INTEGRATE_SUBLEVELS
NAME:
Integrate_Sublevels
PURPOSE:
Function to integrate the sublevel values created by Create_Sublevels
to provide average layer temperature and absorber amount. Layer
pressure is provided by default, i.e. not from integration.
Adapted from the UMBC INTEG.F function supplied with the AIRS RTA.
CALLING SEQUENCE:
Error_Status = Integrate_Sublevels( Sublevel_Height, & ! Input
Sublevel_Pressure, & ! Input
Sublevel_Temperature, & ! Input
Sublevel_Absorber, & ! Input
n_Per_Layer, & ! Input
H2O_J_Index, & ! Input
Layer_Pressure, & ! Output
Layer_Temperature, & ! Output
Layer_Absorber, & ! Output
RCS_Id =RCS_Id, & ! Revision control
Message_Log=Message_Log ) ! Error messaging
INPUT ARGUMENTS:
Sublevel_Height: Altitude of the atmospheric sublevels.
UNITS: metres, m
TYPE: REAL(fp)
DIMENSION: Rank-1 (Ks)
Ks == number of sublevels
ATTRIBUTES: INTENT(IN)
Sublevel_Pressure: Pressure of the atmospheric sublevels.
UNITS: hectoPascals, hPa
TYPE: REAL(fp)
DIMENSION: Same as input Sublevel_Height argument
ATTRIBUTES: INTENT(IN)
Sublevel_Temperature: Temperature of the atmospheric sublevels.
UNITS: Kelvin, K
TYPE: REAL(fp)
DIMENSION: Same as input Sublevel_Height argument
ATTRIBUTES: INTENT(IN)
Sublevel_Absorber: Absorber concentrations at the atmospheric
sublevels
UNITS: ppmv
TYPE: REAL(fp)
DIMENSION: Rank-2 (Ks x J)
Ks == number of Sublevels
J == number of absorbers
ATTRIBUTES: INTENT(IN)
n_Per_Layer: Number of sublevel for each layer.
Value must be > or = 1.
UNITS: N/A
TYPE: INTEGER
DIMENSION: Scalar
ATTRIBUTES: INTENT(IN)
H2O_J_Index: The "J" dimension array index position
of water vapor in the input SubLevel_Absorber
array - which is dimensioned Ks x J.
This is necessary to properly convert the
sublevel absorber amounts from ppmv to
kmol.cm^-2.
UNITS: N/A
TYPE: INTEGER
DIMENSION: Scalar
ATTRIBUTES: INTENT(IN)
OPTIONAL INPUT ARGUMENTS:
Message_Log: Character string specifying a filename
in which any Messages will be logged.
If not specified, or if an error occurs
opening the log file, the default action
is to output Messages to standard output.
UNITS: N/A
TYPE: CHARACTER(*)
DIMENSION: Scalar
ATTRIBUTES: INTENT(IN), OPTIONAL
OUTPUT ARGUMENTS:
Layer_Pressure: Average pressure of the atmospheric layers
UNITS: hectoPascals, hPa
TYPE: REAL(fp)
DIMENSION: Rank-1 (K-1)
K-1 == number of layers
ATTRIBUTES: INTENT(IN)
Layer_Temperature: Average temperature of the atmospheric layers
UNITS: Kelvin, K
TYPE: REAL(fp)
DIMENSION: Same as output Layer_Pressure argument
ATTRIBUTES: INTENT(IN)
Layer_Absorber: Average absorber concentrations of the
atmospheric layers
UNITS: kmol.cm^-2.
TYPE: REAL(fp)
DIMENSION: Rank-2 (K-1 x J)
K-1 == number of layers
J == number of absorbers
ATTRIBUTES: INTENT(IN)
OPTIONAL OUTPUT ARGUMENTS:
RCS_Id: Character string containing the Revision Control
System Id field for the module.
UNITS: N/A
TYPE: CHARACTER(*)
DIMENSION: Scalar
ATTRIBUTES: INTENT(OUT), OPTIONAL
FUNCTION RESULT:
Error_Status: The return value is an integer defining the error
status. The error codes are defined in the
ERROR_HANDLER module.
If == SUCCESS the calculation was successful
== FAILURE an unrecoverable error occurred
UNITS: N/A
TYPE: INTEGER
DIMENSION: Scalar
PROCEDURE:
The average layer pressure is simply determined using,
p(k) - p(k-1)
Layer_Pressure(k) = --------------------
LOG( p(k)/p(k-1) )
The average layer temperature is determined by summing
the density weighted layer temperature T.rho subLAYER
across the sublayers and normalising by the sum of the
subLAYER density,
__ N(k)
\
> Trho [ units of kmol.cm^-2.ppmv^-1.K ]
/__
1
Layer_Temperature = -----------
__ N(k)
\
> rho [ units of kmol.cm^-2.ppmv^-1 ]
/__
1
__ N(k)
\ 1.0e-11
> --------- * dz * p
/__ R
1
= ---------------------------
__ N(k)
\ 1.0e-11
> --------- * dz * p
/__ R . T
1
__ N(k)
\
> dz . p
/__
1
= ----------------
__ N(k)
\ dz . p
> --------
/__ T
1
in units of Kelvin
In the UMBC KLAYERS code, the numerator corresponds to the final
TSUM value (with each sublayer value corresponding to RJUNK),
the denominator to AJUNK, and the result to TLAY.
The average layer absorber amount is determined by simply summing
the sublayer absorber amount across the sublayers,
__ N(k)
\ Trho . ppmv
Layer_Absorber = > -------------
/__ T
1
__ N(k)
\ 1.0e-11 ppmv
= > --------- . dz . p .------
/__ R T
1
in units of kmol.cm^-2
This corresponds to ASUM (and eventually ALAY) in the
UMBC KLAYERS code.
Currently, N is independent of k. That is, the same number of sublevels
is assumed for each layer.
CREATION HISTORY:
Written by: Paul van Delst, CIMSS/SSEC 19-Jan-2001
paul.vandelst@ssec.wisc.edu
