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Geisa inital import
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4   <TITLE>Cross Sections Data</TITLE>
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10<P>  <BR>
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13<CENTER><TABLE BORDER=10 WIDTH="90%" BGCOLOR="#FFFF00" COLS="1" >
14<TR>
15<TD>
16<CENTER><P><B><FONT COLOR="#FF0000">GEISA-97 Infrared absorption cross-sections
17databank description files</FONT></B>  </P></CENTER>
18</TD>
19</TR>
20</TABLE></CENTER>
21
22<P>   In the GEISA-97 cross-sections file, the spectroscopic parameters
23related to heavy molecules, like the CFC's, are not stored following the
24usual standard (i.e. via line position, intensity, halfwidth, etc.), but
25principally as absorption cross-sections determined through the following
26expression:</P>
27
28<P><IMG SRC="/icons-geisa/equ1.gif" HEIGHT=50 WIDTH=180 ALIGN=CENTER>
29</P>
30
31<P>where <I><FONT FACE="Symbol">w</FONT></I> is a frequency (cm<SUP>-1</SUP>);
32<I><FONT FACE="Symbol">s(w)</FONT></I> is the absorption cross section
33(cm<SUP><FONT SIZE=-2>2</FONT></SUP> molecule<SUP><FONT SIZE=-2>-1</FONT></SUP>);
34<I><FONT FACE="Symbol">I<FONT SIZE=-2>0</FONT>(w)</FONT></I> and <I><FONT FACE="Symbol">I(w)</FONT></I>
35are the intensities, at the frequency <I><FONT FACE="Symbol">w</FONT></I>,
36of the incident and transmitted radiation, respectively; <I>n</I> is the
37concentration of the molecules (molecule cm<SUP><FONT SIZE=-2>-3</FONT></SUP>)
38and <I>l</I> the optical path length (cm). It is the <I><FONT FACE="Symbol">s(w)</FONT></I>
39value derived from high-resolution experimental data that is cataloged
40in the GEISA cross-sections file. </P>
41
42<P>Since <A HREF="http://ara.lmd.polytechnique.fr/geisaen.html">GEISA-92</A>,
43the GEISA-97 cross-sections databank has been significantly updated and
44extended. The data on CFC13, CFC14, CFC32, CFC113, CFC114, and CFC115 (Massie
45et al., 1991; Mc Daniel et al., 1991) have been kept from GEISA92, and
46the CFC12 existing data (Massie et al., 1991, Mc Daniel et al., 1991) removed.
47New cross-sections have been cataloged for the following compounds: CFC11
48(Li and Varanasi, 1994); CFC12 (Varanasi and Nemtchinov, 1994); HCFC22
49(Varanasi et al., 1994 and Clerbaux et al., 1993); HCFC123, HCFC124, HCFC125,
50HCFC134a, HCFC141b, HCFC142b, HFC152a, HCFC225ca, and HCFC225cb (Clerbaux
51et al., 1993); HFC32 and HFC143a (Smith et al., 1996, 1998); HFC134 (Smith
52et al., 1998); N<SUB>2</SUB>O<SUB>5</SUB> (Massie et al., 1985); SF<SUB>6</SUB>
53(Varanasi et al., 1994); ClONO<SUB>2</SUB> (Orphal et al., 1994). This
54represents a total of 23 molecules, in the spectral range 556.380-1763.642
55cm<SUP>-1</SUP>. <BR>
56  <A HREF="geisa_crs_all.txt">Table 1</A>, partitioned by molecule, lists the
57whole contents of the GEISA97 cross-sections file. For each of the 23 molecules,
58its name and corresponding code for the management of the cross-sections
59database (see text below) is given in column 1. The atmospheric conditions,
60temperature (T) in K and pressure (P) in Pa, are listed in columns two
61and three, respectively. For a given couple, T and P: the fourth column
62gives the number of available cross-sections<FONT SIZE=+0> (Lines)</FONT>,
63columns five and six, the minimum (<FONT SIZE=+0>nu.min</FONT>) and maximum
64(<FONT SIZE=+0>nu.max</FONT>) frequency (cm<SUP>-1</SUP>) values, and columns
65seven and eight, the corresponding minimum (<FONT SIZE=+0>Min.I</FONT>)
66and maximum (<FONT SIZE=+0>Max.I</FONT>) cross-sections values (cm<SUP>2
67</SUP>molecule<SUP>-1</SUP>), respectively. Note that, if the pressure
68is set to zero, it means, in the case of HFC32, 134a, 134, 143a, 152a,
69HCFC123, 124, 141b, 225ca, 225cb, that the cross-sections have been measured
70for a pure vapor (non-air broadened); for other molecules, it means that
71the the pressure value has not been given explicitly by the authors, but
72it should correspond to that of the US standard atmosphere, for a given
73temperature value. The total number of available cross-sections of the
74related molecule is provided at the bottom of each corresponding sub-table.
75</P>
76
77<P>New results on CFC's cross sections have been obtained beyond this issue
78of the database and will be included in the next issue of GEISA. These
79new data provide an extension of the number of temperature and pressure
80conditions (more than 50, including polar) for CFC11 and CFC12, and also
81new results for CF<SUB>4</SUB> and CCl<SUB>4</SUB> at more than 50 temperature
82and pressure conditions (including polar). </P>
83
84<UL>
85<P>  Extractions from this databank can be made thanks to its <A HREF="geisa_gs_soft.html#cross">management
86software</A>.<BR>
87  </P>
88</UL>
89
90<CENTER><P> <B><A HREF="geisa_jqsrt_ar.html"> REFERENCES<BR>
91</A></B>  </P></CENTER>
92
93<CENTER><TABLE BORDER=7 CELLSPACING=0 CELLPADDING=0 WIDTH="85%" BGCOLOR="#FFFF00" >
94<TR>
95<TD>
96<CENTER><P><A HREF="geisa_gs_soft.html#cross">[GEISA-97 Infrared absorption cross-sections
97databank management software description]</A></P></CENTER>
98</TD>
99</TR>
100</TABLE></CENTER>
101
102<CENTER><TABLE BORDER=7 CELLSPACING=0 CELLPADDING=0 WIDTH="85%" BGCOLOR="#FFFF00" >
103<TR>
104<TD>
105<CENTER><P><A HREF="geisa_ascii_un.html">[More about features of ASCII files]</A></P></CENTER>
106</TD>
107</TR>
108</TABLE></CENTER>
109
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