Partitioning and budget of inorganic and organic chlorine species observed by MIPAS-B and TELIS in the Arctic in March 2011

Abstract

Abstract. The Arctic winter 2010/11 was characterized by a persisting vortex with extremely cold temperatures in the lower stratosphere above northern Scandinavia leading to a strong activation of chlorine compounds (ClOx) like Cl, Cl2, ClO, ClOOCl, OClO, and HOCl which rapidly destroyed ozone when sunlight returned after winter solstice. MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) and TELIS (Terahertz and submillimeter Limb Sounder) balloon measurements obtained in northern Sweden on 31 March 2011 inside the polar vortex have provided vertical profiles of inorganic and organic chlorine species as well as diurnal variations of ClO around sunrise over the whole altitude range in which chlorine is undergoing activation and deactivation. This flight was performed at the end of the winter during the last phase of ClOx deactivation. The complete inorganic and organic chlorine partitioning and budget in the stratosphere has been derived by combining MIPAS-B and TELIS simultaneously observed molecules. A total chlorine amount of 3.41 ± 0.30 ppbv is inferred from the measurements. This value is in line with previously carried out stratospheric observations confirming the slightly decreasing chlorine trend in the stratosphere. Observations are compared and discussed with the output of a multi-year simulation performed with the Chemistry Climate Model EMAC (ECHAM5/MESSy Atmospheric Chemistry). The simulated stratospheric total chlorine amount is in accordance with the MIPAS-B/TELIS observation taking into account the fact that some chlorine source gases and very short lived species are not included in the model.

Performance Assessment of Balloon-Borne Trace Gas Sounding with the Terahertz Channel of TELIS

“…The noise error is no more than 1%, whereas the retrieval error including systematic effects (mainly spectroscopy) reaches roughly 8-10%. More information about the MIPAS-B retrieval scheme is detailed in [52] and references therein.…”

“…Hydrogen chloride (HCl) is the main chlorine reservoir species monitored by both channels of TELIS, whereas the active chlorine species chlorine monoxide (ClO) is only observed by the 480-650 GHz channel. These species have been used for a quantitative estimation of the total budget of chlorine in the stratosphere and allow a better understanding of their impact on stratospheric ozone depletion [51,52]. Carbon monoxide (CO) is a tracer related to atmospheric transport as a result of its long lifetime in the atmosphere.…”