MIPAS database: New HNO3 line parameters at 7.6 μm validated with MIPAS satellite measurements

Abstract

Improved line positions and intensities have been generated for the 7.6 m spectral region of nitric acid. They were obtained relying on a recent reinvestigation of the nitric acid band system at 7.6 m and comparisons of HNO3 volume mixing ratio profiles retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) limb emission radiances in the 11 and 7.6 m domains. This has led to an improved database called MIPAS-2015. Comparisons with available laboratory information (individual line intensities, integrated absorption cross sections, and absorption cross sections) show that MIPAS-2015 provides an improved description of the 7.6 m region of nitric acid. This study should help to improve HNO3 satellite retrievals by allowing measurements to be performed simultaneously in the 11 and 7.6 m micro-windows. In particular, it should be useful to analyze existing MIPAS and IASI spectra as well as spectra to be recorded by the forthcoming Infrared Atmospheric Sounding Interferometer-New Generation (IASI-NG) instrument.