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from the topic by Goody and Yung (1996):
10
−6
b
(
)
P
[+10
−6
P
(139. 855 − 2. 093
T
)]
5. 407(1 + 0. 003661
T
)
−
P
w
8. 319 − 0. 0907
=
λ
m
−1
,
λ
−2
(1.27)
1 + 0. 003661
T
29498. 1
146 −
255. 4
41 −
λ
=
b
(
)
64. 328 +
−2
+
,
λ
λ
−2
where
P
w
is the partial pressure of the water vapor. It should be noted that
in (1.27) wavelength is measured in microns (
µ
m), pressure - in Pascals (Pa),
temperature - in degrees Celsius (
◦
C).
Two kinds of the input data for calculating cross-section of the molecular
absorption are available in the short wavelength range.
The data of the first kind are tabulated as a dependence of the experimental
cross-sections upon wavelength and in some cases upon temperature, i. e.
C
a
,
i
(
λ
,
T
). Regretfully, the databases of mentioned cross-sections are not freely
accessible nowadays. Therefore, during the concrete calculation we have been
using the database collected from Sedunov et al. (1991) and Bass and Paur
(1984) together with the data taken from the base of GOMETRAN computer
code (Pozanov et al. 1995; Vasilyev et al. 1998) with the kind permission of
its authors Vladimir Rozanov and Yuri Timofeyev. The cross-section of the
molecular absorption of the specific gas (subscript “
i
”isomitted)iscalculated
for the data of the first kind as a simple linear interpolation over the look-up
table:
λ
=
∆
1
(
λ
∆
1
(
T
,
k
)
C
a
(
λ
j
,
T
k
)+
∆
1
(
λ
∆
2
(
T
,
k
)
C
a
(
λ
j
,
T
k
+1
)
C
a
(
,
T
)
,
j
)
,
j
)
(1.28)
∆
2
(
λ
∆
1
(
T
,
k
)
C
a
(
λ
j
+1
,
T
k
)+
∆
2
(
λ
∆
2
(
T
,
k
)
C
a
(
λ
j
+1
,
T
k
+1
),
+
,
j
)
,
j
)
where
y
l
+1
−
y
y
l
+1
−
y
l
y
−
y
l
y
l
+1
−
y
l
∆
1
(
y
,
l
)
=
∆
2
(
y
,
l
)
=
,
,
and numbers
j
and
k
are chosen over nodes of the table grid under the con-
ditions
λ
j
≤
λ
≤
λ
j
+1
,
T
k
≤
≤
T
k
+1
. In the absence of the temperature
dependence it is enough to set formally
T
∆
1
(
T
,
k
)
=
∆
2
(
T
,
k
)
=
0 in (1.28).
Thedataofthesecondkinddescribetheseparateabsorptionlinesofthe
gases (parameters of the fine structure). The theoretical aspects of the calcu-
lations using these data have been interpreted in detail, e. g. in the topic by
Penner (1959). For the concrete calculations, we have been using the database
HITRAN-92 (Rothman et al. 1992). The volume coefficient of the molecular
absorption according to the data of the second kind depends on the tempera-
1and
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