Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 18, 5691-5697, 2018
https://doi.org/10.5194/acp-18-5691-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
24 Apr 2018
Using satellite measurements of N2O to remove dynamical variability from HCl measurements
Richard S. Stolarski1, Anne R. Douglass2, and Susan E. Strahan2 1Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, USA
2Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA
Abstract. Column HCl measurements show deviations from the expected slow decline following the regulation of chlorine-containing compounds by the Montreal Protocol. We use the simultaneous measurements of N2O and HCl by the Microwave Limb Sounder (MLS) instrument on the Aura satellite to examine this problem. We find that the use of N2O measurements at a specific altitude to represent the impact of dynamical variability on HCl results in a derived linear trend in HCl that is negative (ranging from −2.5 to 5.3 % decade−1) at all altitudes between 68 and 10 hPa. These trends are at or near 2σ statistical significance at all pressure levels between 68 and 10 hPa. This shows that analysis of simultaneous measurements of several constituents is a useful approach to identify small trends from data records that are strongly influenced by dynamical interannual variability.
Citation: Stolarski, R. S., Douglass, A. R., and Strahan, S. E.: Using satellite measurements of N2O to remove dynamical variability from HCl measurements, Atmos. Chem. Phys., 18, 5691-5697, https://doi.org/10.5194/acp-18-5691-2018, 2018.
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Short summary
Detecting trends in short data sets of stratospheric molecules is difficult because of variability due to dynamical fluctuations. We suggest that one way around this difficulty is using the measurements of one molecule to remove dynamical variability from the measurements of another molecule. We illustrate this using Aura MLS measurements of N2O to help us sort out issues in the determination of trends in HCl. This shows that HCl is decreasing throughout the middle stratosphere as expected.
Detecting trends in short data sets of stratospheric molecules is difficult because of...
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