Atmospheric vertical profiles of O3, N2O, CH4, CCl2F2, and H2O retrieved from external-cavity quantum-cascade laser heterodyne radiometer measurements.

Atmospheric vertical profiles of ozone, nitrous oxide, methane, dichlorodifluoromethane, and water are retrieved from data collected with a widely tunable external-cavity quantum-cascade laser heterodyne radiometer (EC-QC-LHR) covering a spectral range between 1120 and 1238  cm−1. The instrument was operated in solar occultation mode during a two-month measurement campaign at Rutherford Appleton Laboratory in Oxfordshire, UK, in winter 2010/2011, and ultrahigh-resolution (60 MHz or 0.002  cm−1) transmission spectra were recorded for multiple narrow spectral windows (∼1  cm−1 width) specific to each molecule. The ultrahigh spectral resolution of the EC-QC-LHR allows retrieving altitudinal profiles from transmission spectra that contain only few (1–3) significant absorption lines of a target molecule. Profiles are validated by comparing with European Centre for Medium-Range Weather Forecasts operational atmospheric profiles (ozone and water), with other data in the literature (nitrous oxide, methane, dichlorodifluoromethane), and with retrievals from a lower resolution (600 MHz or 0.02  cm−1) Fourier transform spectroscopy data that were also recorded during the measurement campaign.