Odin stratospheric proxy NOy measurements and climatology S. Brohede1, C. A. McLinden2, J. Urban1, C. S. Haley3, A. I. Jonsson4, and D. Murtagh1 1Department of Radio and Space Science, Chalmers University of Technology, 412 96 Göteborg, Sweden 2Environment Canada, 4905 Dufferin Street, Toronto, Ontario, M3H 5T4, Canada 3Centre for Research in Earth and Space Science, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3, Canada 4Department of Physics, University of Toronto, M5S 1A7 Toronto, Ontario, Canada
Abstract. Five years of OSIRIS (Optical Spectrograph and InfraRed Imager System) NO2
and SMR (Sub-millimetre and Millimetre Radiometer) HNO3 observations from
the Odin satellite, combined with data from a photochemical box model, have
been used to construct a stratospheric proxy NOy data set including the
gases: NO, NO2, HNO3, 2×N2O5
and ClONO2. This Odin NOy
climatology is based on all daytime measurements and contains monthly mean
and standard deviation, expressed as mixing ratio or number density, as
function of latitude or equivalent latitude (5° bins) on 17 vertical
layers (altitude, pressure or potential temperature) between 14 and 46 km.
Comparisons with coincident NOy profiles from the Atmospheric Chemistry
Experiment-Fourier Transform Spectrometer (ACE-FTS) instrument were used to
evaluate several methods to combine Odin observations with model data. This
comparison indicates that the most appropriate merging technique uses OSIRIS
measurements of NO2, scaled with model NO/NO2 ratios, to estimate NO.
The sum of 2×N2O5 and ClONO2 is estimated from
uncertainty-based weighted averages of scaled observations of SMR HNO3 and
OSIRIS NO2. Comparisons with ACE-FTS suggest the precision (random error)
and accuracy (systematic error) of Odin NOy profiles are about 15% and
20%, respectively. Further comparisons between Odin and the Canadian Middle
Atmosphere Model (CMAM) show agreement to within 20% and 2 ppb throughout
most of the stratosphere except in the polar vortices. The combination of
good temporal and spatial coverage, a relatively long data record, and good
accuracy and precision make this a valuable NOy product for various
atmospheric studies and model assessments.
Citation: Brohede, S., McLinden, C. A., Urban, J., Haley, C. S., Jonsson, A. I., and Murtagh, D.: Odin stratospheric proxy NOy measurements and climatology, Atmos. Chem. Phys., 8, 5731-5754, doi:10.5194/acp-8-5731-2008, 2008.