Temperature-dependence of the near-UV absorption of water vapor in the 290–350nm range

Abstract

Water vapor plays a critical role in the energy balance of the Earth's atmosphere. But there are limited experimental measurements of single photon water vapor absorption spectra and absorption strengths in the near-UV region. We determined the temperature-dependent absorption cross-sections of water vapor at 1 nm increments in the 290–350 nm range by using cavity ring-down spectroscopy. Water vapor exhibited structured absorption bands in this region, with cross-sections ranging from 1.4 × 10−25 to 6.0 × 10−25 cm2/molecule at 283 K; 1.6 × 10−25 to 8.9 × 10−25 cm2/molecule at 313 K; and 1.9 × 10−25 to 1.0 × 10−24 cm2/molecule at 333 K. A radiative transfer model was used to evaluate atmospheric impacts of water vapor near-UV absorption using laboratory temperature-dependent cross-section data.