Recent Northern Hemisphere stratospheric HCl increase due to atmospheric circulation changes

Mahieu, Emmanuel; Chipperfield, Martyn P.; Notholt, Justus; Reddmann, T.; Anderson, J.; Bernath, P. F.; Blumenstock, Thomas; Coffey, M. T.; Dhomse, Sandip; Feng, Wuhu; Franco, Bruno; Froidevaux, L.; Griffith, David; Hannigan, James W.; Hase, Frank; Hossaini, Ryan; Jones, Nicholas; Morino, Isamu; Murata, Isao; Nakajima, H.; Palm, Mathias; Paton-Walsh, Clare; Russell, James M.; Schneider, Mat­thias; Servais, Christian; Smale, Dan; Walker, Kaley A.

doi:10.1038/nature13857

Cited by 112 publications

(135 citation statements)

References 21 publications

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“…While the beginning and ending dates are slightly different, Fig. 10 is qualitatively consistent with the conclusion in Mahieu et al (2014) that the air in the SH midlatitude lower stratosphere is younger in 2010/2011 than in 2005/2006, while the opposite is true in the NH. Stiller et al (2012) show an age-of-air trend from 2002 to 2010 which exhibits the same interhemispheric difference over much of the lower stratosphere at mid-latitudes, but they do show older air over the latitude of Lauder above 25 km.…”

Section: Decadal Changes In O 3 and N 2 Osupporting

confidence: 79%

Unusual stratospheric ozone anomalies observed in 22 years of measurements from Lauder, New Zealand

et al. 2015

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Abstract. The Microwave Ozone Profiling Instrument (MOPI1) has provided ozone (O 3 ) profiles for the Network for the Detection of Atmospheric Composition Change (NDACC) at Lauder, New Zealand (45.0 • S, 169.7 • E), since 1992. We present the entire 22-year data set and compare with satellite O 3 observations. We study in detail two particularly interesting variations in O 3 . The first is a large positive O 3 anomaly that occurs in the mid-stratosphere (∼ 10-30 hPa) in June 2001, which is caused by an anticyclonic circulation that persists for several weeks over Lauder. This O 3 anomaly is associated with the most equatorward June average tracer equivalent latitude (TrEL) over the 36-year period for which the Modern Era RetrospectiveAnalysis for Research and Applications (MERRA) reanalysis is available. A second, longer-lived feature, is a positive O 3 anomaly in the mid-stratosphere (∼ 10 hPa) from mid-2009 until mid-2013. Coincident measurements from the Aura Microwave Limb Sounder (MLS) show that these high O 3 mixing ratios are well correlated with high nitrous oxide (N 2 O) mixing ratios. This correlation suggests that the high O 3 over this 4-year period is driven by unusual dynamics. The beginning of the high O 3 and high N 2 O period at Lauder (and throughout this latitude band) occurs nearly simultaneously with a sharp decrease in O 3 and N 2 O at the equator, and the period ends nearly simultaneously with a sharp increase in O 3 and N 2 O at the equator.

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Section: Decadal Changes In O 3 and N 2 Osupporting

confidence: 79%

Unusual stratospheric ozone anomalies observed in 22 years of measurements from Lauder, New Zealand

et al. 2015

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“…The positive SCS is almost double in magnitude in the NH midlatitude and low latitude, suggesting a much enhanced BD circulation during solar maximum 23 [see also Mahieu et al, 2014]. In summary, Figure 4 shows that very different …”

Section: 1002/2016gl069958mentioning

confidence: 74%

On the ambiguous nature of the 11 year solar cycle signal in upper stratospheric ozone

Dhomse

Chipperfield

Damadeo

et al. 2016

Geophysical Research Letters

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Up to now our understanding of the 11 year ozone solar cycle signal (SCS) in the upper stratosphere has been largely based on the Stratospheric Aerosol and Gas Experiment (SAGE) II (v6.2) data record, which indicated a large positive signal which could not be reproduced by models, calling into question our understanding of the chemistry of the upper stratosphere. Here we present an analysis of new v7.0 SAGE II data which shows a smaller upper stratosphere ozone SCS, due to a more realistic ozone‐temperature anticorrelation. New simulations from a state‐of‐art 3‐D chemical transport model show a small SCS in the upper stratosphere, which is in agreement with SAGE v7.0 data and the shorter Halogen Occultation Experiment and Microwave Limb Sounder records. However, despite these improvements in the SAGE II data, there are still large uncertainties in current observational and meteorological reanalysis data sets, so accurate quantification of the influence of solar flux variability on the climate system remains an open scientific question.

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“…During the period of MIPAS observations they found that stratospheric AoA decreased in the lower stratosphere but showed interhemispheric differences in the trend above about 20 km. Also, despite the ongoing monotonic decrease of near-surface chlorine source gases, recent ground-based and satellite remote-sensing measurements have shown a significant increase in hydrogen chloride (HCl), the main stratospheric chlorine reservoir, in the lower stratosphere of the Northern Hemisphere between 2007 and 2011 (Mahieu et al, 2014). By comparison to similar SLIM-CAT simulations as used here, this trend "anomaly" was attributed to multiyear variability in the stratospheric circulation and dynamics.…”

Section: Trendsmentioning

confidence: 84%

Satellite observations of stratospheric hydrogen fluoride and comparisons with SLIMCAT calculations

et al. 2016

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Abstract. The vast majority of emissions of fluorinecontaining molecules are anthropogenic in nature, e.g. chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Many of these fluorine-containing species deplete stratospheric ozone and are regulated by the Montreal Protocol. Once in the atmosphere they slowly degrade, ultimately leading to the formation of hydrogen fluoride (HF), the dominant reservoir of stratospheric fluorine due to its extreme stability. Monitoring the growth of stratospheric HF is therefore an important marker for the success of the Montreal Protocol.We report the comparison of global distributions and trends of HF measured in the Earth's atmosphere by the satellite remote-sensing instruments ACE-FTS (Atmospheric Chemistry Experiment Fourier transform spectrometer), which has been recording atmospheric spectra since 2004, and HALOE (HALogen Occultation Experiment), which recorded atmospheric spectra between 1991 and 2005, with the output of SLIMCAT, a state-of-the-art threedimensional chemical transport model. In general the agreement between observation and model is good, although the ACE-FTS measurements are biased high by ∼ 10 % relative to HALOE. The observed global HF trends reveal a substantial slowing down in the rate of increase of HF since the 1990s: 4.97 ± 0.12 % year −1 (1991-1997; HALOE), 1.12 ± 0.08 % year −1 (1998 HALOE), and 0.52 ± 0.03 % year −1 (2004-2012 ACE-FTS). In comparison, SLIMCAT calculates trends of 4.01, 1.10, and 0.48 % year −1 , respectively, for the same periods; the agreement is very good for all but the earlier of the two HALOE periods. Furthermore, the observations reveal variations in the HF trends with latitude and altitude; for example, between 2004 and 2012 HF actually decreased in the Southern Hemisphere below ∼ 35 km. An additional SLIMCAT simulation with repeating meteorology for the year 2000 produces much cleaner trends in HF with minimal variations with latitude and altitude. Therefore, the variations with latitude and altitude in the observed HF trends are due to variability in stratospheric dynamics on the timescale of a few years. Overall, the agreement between observation and model points towards the ongoing success of the Montreal Protocol and the usefulness of HF as a metric for stratospheric fluorine.

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Recent Northern Hemisphere stratospheric HCl increase due to atmospheric circulation changes

Cited by 112 publications

References 21 publications

Unusual stratospheric ozone anomalies observed in 22 years of measurements from Lauder, New Zealand

Unusual stratospheric ozone anomalies observed in 22 years of measurements from Lauder, New Zealand

On the ambiguous nature of the 11 year solar cycle signal in upper stratospheric ozone

Satellite observations of stratospheric hydrogen fluoride and comparisons with SLIMCAT calculations

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