Pressure-broadening coefficients and line strengths of H2O near 1.39 μm:: application to the in situ sensing of the middle atmosphere with balloonborne diode lasers

Since 1998, we have developed two balloonborne diode laser spectrometers, SDLA and micro-SDLA, to yield in situ concentration data of H2O in the middle atmosphere by absorption spectroscopy in the 1.39 mu m spectral range. In this paper, we revisit the molecular parameters, line intensities and pressure-broadening coefficients, for several lines of the nu(1) + nu(3) and 2 nu(1) bands, which are useful for the monitoring of atmospheric H2O. The new values are thoroughly compared to existing molecular database and previous determinations. Calculations are performed to yield the pressure-effect coefficients: the theoretical model is described and the ab initio predictions are compared to laboratory measurements achieved with a laser diode spectrometer. The improvement in the H2O monitoring obtained with the new set of molecular data is evaluated directly from vertical H2O concentration profiles. (c) 2004 Elsevier Ltd. All rights reserved.