Long-term trends of inorganic chlorine from ground-based infrared solar spectra: Past increases and evidence for stabilization

Authors

C P. Rinsland, NASA Langley Research Center
E Mahieu, University of Liege
R Zander, University of Liege
Nicholas Jones, University of WollongongFollow
M P. Chipperfield, University of Leeds
A Goldman, University of Denver
J Anderson, Hampton University
J M. Russell III, Hampton University
P Demoulin, University of Liege
J Notholt, University of Bremen
G C. Toon, Jet Propulsion Laboratory
Jean-Francois Blavier, Jet Propulsion Laboratory
B Sen, Jet Propulsion Laboratory
R Sussmann, IMK-IFU
S W. Wood, National Institute of Water and Atmospheric Research
A Meier, University of Wollongong
D W. T Griffith, University of WollongongFollow
L Chiou, Science Applications International Corporation
F Murcray, University of Denver
T M. Stephen, University of Denver
Frank Hase, IMK-ASF
S Mikuteit, IMK-ASF
A Schultz, Alfred Wegener Institute for Polar and Marine ResearchFollow
T Blumenstock, IMK-ASF

RIS ID

24143

Publication Details

Rinsland, C. P., Mahieu, E., Zander, R., Jones, N. B., Chipperfield, M. P., Goldman, A., Anderson, J., Russell III, J. M., Demoulin, P., Notholt, J., Toon, G. C., Blavier, J., Sen, B., Sussmann, R., Wood, S. W., Meier, A., Griffith, D. W. T., Chiou, L. S., Murcray, F. J., Stephen, T. M., Hase, F., Mikuteit, S., Schultz, A. & Blumenstock, T. (2003). Long-term trends of inorganic chlorine from ground-based infrared solar spectra: Past increases and evidence for stabilization. Journal of Geophysical Research, 108 (D8), 1-21.

Abstract

Long-term time series of hydrogen chloride (HCl) and chlorine nitrate (ClONO₂) total column abundances has been retrieved from high spectral resolution ground-based solar absorption spectra recorded with infrared Fourier transform spectrometers at nine NDSC (Network for the Detection of Stratospheric Change) sites in both Northern and Southern Hemispheres. The data sets span up to 24 years and most extend until the end of 2001. The time series of Cl_y (defined here as the sum of the HCl and ClONO₂ columns) from the three locations with the longest time-span records show rapid increases until the early 1990s superimposed on marked day-to-day, seasonal and inter-annual variability. Subsequently, the buildup in Cl_y slows and reaches a broad plateau after 1996, also characterized by variability. A similar time evolution is also found in the total chlorine concentration at 55 km altitude derived from Halogen Occultation Experiment (HALOE) global observations since 1991. The stabilization of inorganic chlorine observed in both the total columns and at 55 km altitude indicates that the near-global 1993 organic chlorine (CCl_y) peak at the Earth's surface has now propagated over a broad altitude range in the upper atmosphere, though the time lag is difficult to quantify precisely from the current data sets, due to variability. We compare the three longest measured time series with two-dimensional model calculations extending from 1977 to 2010, based on a halocarbon scenario that assumes past measured trends and a realistic extrapolation into the future. The model predicts broad Cl_y maxima consistent with the long-term observations, followed by a slow Cl_y decline reaching 12–14% relative to the peak by 2010. The data reported here confirm the effectiveness of the Montreal Protocol and its Amendments and Adjustments in progressively phasing out the major man-related perturbations of the stratospheric ozone layer, in particular, the anthropogenic chlorine-bearing source gases.