A spectroscopic database for water vapor between 5850 and 8340 cm−1

Abstract

An accurate and complete empirical spectroscopic database is constructed for natural water in the 5850-8340 cm-1 near infrared region (1.71-1.20 μm). The global list includes more than 46500 transitions of the six most abundant isotopologues (H 2 16 O, H 2 18 O, H 2 17 O, HD 16 O, HD 17 O, HD 18 O) in natural isotopic abundance with intensity greater than 1×10-29 cm/molecule. All line positions were obtained by difference of empirically determined energy values. These empirical determinations are mostly based on extensive investigations of water spectra by high sensitivity CRDS complemented with literature data. In particular, the sets of energy levels of the minor isotopologues have been significantly enlarged from very recent analysis of CRDS spectra of D, 18 O and 17 O enriched water samples. The empirical line positions were associated to experimental intensity values from the literature obtained by FTS for the strong lines and CRDS for weaker lines. The list is made mostly complete by including a large number of weak transitions not yet detected, with empirical positions calculated from empirical levels associated with variational intensities. Air-and selfbroadening coefficients have been added to each transition using the most recent version of the algorithm used for the HITRAN and GEISA databases. Examples of comparison of CRDS spectra to simulations based on the HITRAN2012 list illustrate the advantages of our database. The relative merit of experimental and variational line intensities is discussed. A separate line list combining empirical line positions and variational intensities is provided. Future improvements from combination of experimental and variational intensities are suggested.

Accurate laboratory determination of the near‐infrared water vapor self‐continuum: A test of the MT_CKD model

“…In fact, similar to the above CRDS‐DFB measurements in the 2.1 µm window, in order to derive the cross‐section values, we preferred to monitor the pressure dependence of the cavity losses at fixed spectral points, instead of recording series of successive spectra at different pressures. Overall, 56 spectral points located in spectral intervals free of absorption lines were selected on the basis of our previous extensive CRDS spectra of water vapor in the 7548–8340 cm −1 range [ Campargue et al ., ; Mikhailenko et al ., ]. The CRDS cell pressure was continuously monitored by a capacitance gauge (model 626B from MKS Instruments; 100 Torr, 0.25% accuracy of reading).…”

“…For instance, water lines with intensity as small as 5 × 10 −30 cm/molecule were measured. On the basis of these extensive CRDS measurements, we have recently released a spectroscopic database for natural water in the 5850–8340 cm −1 range which significantly improves the HITRAN2012 line list in the region, both in terms of completeness and accuracy [ Mikhailenko et al ., ].…”

“…Thus, Rayleigh scattering losses represent at most a few % of the absorption continuum (Figure ). Second, for each pressure value, simulation of the water vapor rovibrational spectrum, α WML , is performed on the basis of our spectroscopic database [ Mikhailenko et al ., ], using a Voigt profile and the [−25, +25 cm −1 ] cutoff for the line wings. Third, the latter α WML contribution is subtracted from experimental data and the pressure dependence of the absorption, ( α cav + α WCS ), is fitted by a quadratic polynomial in P with its linear term constrained to 0.…”

Validation of spectroscopic data in the 1.27 µm spectral region by comparisons with ground-based atmospheric measurements

“…Tests were also made with the most recent data of H2O in the 2019 version of the GEISA database [39]. In this spectral region, the GEISA2019 was updated using line intensities and air-broadening and -shifting coefficients provided in the H2O line list from Mikhailenko et al [40], whereas the line positions were refined using [41]. Note that local discrepancies due to erroneous broadening values of some H2O lines were identified in [40] and GEISA2015 (for the H2O line at 7804.6092 cm -1 for example), and some air-broadening parameters from GEISA2011 were reintroduced in GEISA2019.…”

Water vapor absorption between 5690 and 8340 cm−1: Accurate empirical line centers and validation tests of calculated line intensities

“…On the basis of these measurements [14][15][16][17][18][20][21][22][23] and absorption data available in the literature mostly for the strongest lines [27][28][29][30][31][32][33][34][35][36][37], in 2016, we released an empirical line list for the 5850-8340 cm -1 range [38]. This list corrected a number of deficiencies of the HITRAN2012 line list [39], in particular the absence of many HDO lines of importance in the 1.6 µm window.…”