Abstract
Abstract. This paper introduces a new inversion algorithm for retrievals of stratospheric BrO from the Aura Microwave Limb Sounder. This version is based on the algorithm described by Livesey et al. (2006a) but uses a more realistic atmospheric state to constrain the retrieval. A description of the methodology and an error analysis are presented. Single daily profile precision uncertainty, when taking the ascending-descending (day-night) difference, was found to be up to 40 pptv while systematic error biases were estimated to be less than about 3 pptv. Monthly mean comparisons show broad agreement with other measurements as well as with state-of-the-art numerical models. We infer a 2005 yearly total inorganic Bry using the measured MLS BrO to be 20.3 ± 4.5 pptv, which implies a contribution from very short lived substances to the stratospheric bromine budget of 5 ± 4.5 pptv.
Highlights
Stratospheric O3 destruction has been a great concern since 1985 when massive O3 loss over the Antarctic spring, the famous “O3 hole”, was reported (Farman et al, 1985)
In this paper we introduce a new dataset of global observations of stratospheric BrO from the Aura Microwave Limb Sounder (MLS) instrument
As pointed out by Kovalenko et al (2007), it may be possible to characterize these systematic errors in order to reduce the biases in the polar regions and extend the coverage of the MLS data, this is outside the scope of this study
Summary
Stratospheric O3 destruction has been a great concern since 1985 when massive O3 loss over the Antarctic spring, the famous “O3 hole”, was reported (Farman et al, 1985) Extensive research, both theoretical and observational, showed that this O3 depletion was caused by complex chemical processes involving radicals containing chlorine and less abundant bromine. Stratospheric inorganic bromine (Bry) sources can be classified as (e.g., Wamsley et al, 1998; Montzka et al, 2003) natural and anthropogenic methyl bromide (CH3Br), manufactured long-lived halons (such as CBrClF2 and CBr2F2) and a variety of predominantly natural very short lived substances (VSLS) containing bromine (such as CHBr3, CH2Br2, CH2ClBr) These compounds, when transported to the upper troposphere and stratosphere, are converted into inorganic bromine forms (Bry = Br + BrO + BrONO2 + HOBr + BrCl + HBr) by photolysis or reactions with OH radicals (e.g., Pundt et al, 2002). We infer a new estimate for the BrVy SLS loading
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