Geoscience Reference
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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
=
|λ
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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