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ture T and air pressure P , and is calculated as:
n i T
T
l ( i ) K ( i )
M
W ij ( T )
W ij ( T ) f ij ( P , T ,
κ m =
S ij
,
ν ij ),
ν
=
=
i
1
j
1
(1.29)
exp c 2 E ij
T
1−exp c 2 ν ij
T ,
=
W ij ( T )
where the summarizing is accomplished over the subscript i over all gases, and
it is accomplished over subscript j over all absorption lines of the specific gas;
T is the temperature which the spectroscopic information is presented for
( T =
=
=
296 K); l ( i )
1 for linear molecules and l ( i )
1. 5 for other molecules,
f ij is the function of spectral line contour,
isthewavenumber,corresponds
ν
λ
ν =
to wavelength
(
1
), c 2 is the second radiation constant, S ij , E ij ,
ν ij
are the spectral line parameters from the HITRAN-92 database: the intensity,
transitionenergyintheunitsofthewavenumberandthewavenumberin
the units of the spectral line correspondingly. There is no obvious analytical
expression for the function of spectral line contour f ij in the general case.
Therefore, in our calculations the approximation proposed in Matveev (1972)
is applied:
ln 2
π
1
δ 1
x
=
(1 − x ) exp(− y 2 ln 2) +
f ij ( P , T ,
ν
,
ν ij )
π
(1 + y 2 )
3
2 ln 2 +1+ x
x (1 − x ) 1
π
0. 066 exp(−0. 4 y 2 )−
40 − 5. 5 y 2 + y 4 ,
1
×
= δ 1
= ν ν ij
x
,
y
,
δ 2
δ 1
(1.30)
δ 2 +
δ 2
1
2
2
δ 1 =
δ
δ
δ 2
1−
,
2 +4
3 +0.05
δ 2 +
δ
2 +4
δ
3
T
T
m ij
P
P
δ 2 = d ij
,
2 RT ln 2
µ i
δ 3 = ν ij
c
,
where P
is the pressure, which the spectral information is presented for
( P =
1013mbar), c is the velocity of light in a vacuum, R is the universal gas
constant,
µ i is the molecular mass of gas, d ij , m ij are the line parameters from
theHITRAN-92 database: the semi-intensity breadth of the spectral line caused
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