Abstract
Abstract. The first profile retrieval results of the Terahertz and submillimeter Limb Sounder (TELIS) balloon instrument are presented. The spectra are recorded during a 13-h balloon flight on 24 January 2010 from Kiruna, Sweden. The TELIS instrument was mounted on the MIPAS-B2 gondola and shared this platform with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the mini-Differential Optical Absorption Spectroscopy (mini-DOAS) instruments. The flight took place within the Arctic vortex at an altitude of ≈34 km in chlorine activated air, and both active (ClO) and inactive chlorine (HCl) were measured over an altitude range of respectively ≈16–32 km and ≈10–32 km. In this altitude range, the increase of ClO concentration levels during sunrise has been recorded with a temporal resolution of one minute. During the daytime equilibrium, a maximum ClO level of 2.1 ± 0.3 ppbv has been observed at an altitude of 23.5 km. This equilibrium profile is validated against the ClO profile by the satellite instrument Microwave Limb Sounder (MLS) aboard EOS Aura. HCl profiles have been determined from two different isotopes – H35Cl and H37Cl – and are also validated against MLS. The precision of all profiles is well below 0.01 ppbv and the overall accuracy is therefore governed by systematic effects. The total uncertainty of these effects is estimated to be maximal 0.3 ppbv for ClO around its peak value at 23.5 km during the daytime equilibrium, and for HCl it ranges from 0.05 to 0.4 ppbv, depending on altitude. In both cases the main uncertainty stems from a largely unknown non-linear response in the detector.
Highlights
After the “Montreal Protocol on Substances that Deplete the Ozone Layer” went into effect, anthropogenic chlorofluorocarbons (CFCs) emissions started being phased out
In this paper we present chlorine monoxide (ClO) and hydrogen chloride (HCl) profile retrievals from the 24 January 2010 Terahertz and submillimeter Limb Sounder (TELIS) flight, including a comparison with co-located Microwave Limb Sounder (MLS) measurements and an extensive error analysis
The results presented here pertain to the 480–650 GHz channel developed by SRON in collaboration with the Institute of RadioEngineering and Electronics (IREE), Moscow
Summary
After the “Montreal Protocol on Substances that Deplete the Ozone Layer” went into effect, anthropogenic chlorofluorocarbons (CFCs) emissions started being phased out. In the activated polar vortex, ClO abundances are high but NO2 concentration levels are low as well because of a steady conversion into N2O5 and subsequently into HNO3, favouring the formation of the ClO-dimer during sunset This, together with the MIPAS observations of the nighttime reservoir species ClONO2 and the ClO-dimer, allows for testing ClO formation rates as function of altitude, and as function of temperature and pressure, in atmospheric chemistry models As this formation rate is directly linked to the ClOdimer photo-dissociation rate in the chlorine activated polar vortex, the joint MIPAS-TELIS balloon flight of 2010 makes it very suitable to evaluate the dissociation rates found in laboratory experiments.
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