Each presented ASCII-file contains the cross-section spectra, calculated for one of the PT points of the Mid-Altitude Summer Atmospheric profile (MLS) [1] (see Table 1). The pressure P and temperature T used in the given calculation are shown in the filename.
For example, ‘P2p773-1_T235p2._10km’ means that calculation was performed at P=2.773E-1 atm and T=235.2 К (see Table 1 for 10km).
In each file there are four columns. The first one is the wavenumber grid (in cm-1). The second and third columns are the H2O cross-section spectra (in cm2) multiplied by factor 1020 (for convenience). These spectra have been calculated using the HITRAN-2016 [2] database taking into account only those spectral lines, which are equipped parameters for the Hartmann-Tran Profiles (HTP) [3] calculations. (In this database, out of 313,787 H2O lines, only 2655 lines are equipped with such parameters). Thus the second column is a sum of HTPs and the third one is a sum of usual Voigt profiles. The forth column is their difference. Table 2 demonstrate content of the above mentioned file as an example.
Table 2. Example: content of ‘P0.2773(-1) _T235.2.10km’ file.
| Wavenumber (cm-1) |
HTP (cm2)*1020 |
Voigt (cm2)*1020 |
(HTP-Voigt)*1020 |
| 2690.31072 |
0.1385E-07 |
0.1353E-07 |
0.320E-09 |
| 2690.96608 |
0.2241E-07 |
0.2206E-07 |
0.350E-09 |
| 2691.62144 |
0.4260E-07 |
0.4221E-07 |
0.390E-09 |
| 2691.78528 |
0.5203E-07 |
0.5163E-07 |
0.400E-09 |
| … |
… |
… |
… |
| 3999.67138 |
0.8674E-04 |
0.6769E-04 |
0.190E-04 |
| 3999.75330 |
0.8417E-04 |
0.6518E-04 |
0.190E-04 |
| 3999.83522 |
0.8185E-04 |
0.6293E-04 |
0.189E-04 |
The spectral range is the same in each file (2690-4000 cm-1). In the tables is used efficient nonuniform wavenumber grids for line profiles interpolations with a given accuracy (usually better than 1%). The grid points are condensed at the centers of the lines and become rare in the wings. It makes it possible to obtain essentially more compact files than those, which use uniform grids. But the grids are different in different files.
These files can be considered as demonstration of the spectral look-up tables (LUTs) for replacing direct line-by-line (LBL) calculations of molecular spectra in the forward remote sensing models for taking into account the non-Voigt line shapes. An efficient line-by-line technique of fast computing such as compact and precise LUTs plans to be published in near future.
These files can be considered as examples of compact “lookup tables” (LUTs) for taking into account the non-Voigt line shapes in forward line-by-line (LBL) models used in remote sensing. An effective methodology for calculating such LUTs is planned to be published in the near future. |
