Retrieval of atmospheric (HNO3)-N-15/(HNO3)-N-14 isotope ratio profile from MIPAS/ENVISAT limb-scanning measurements

Year: 2009

Authors: Ridolfi M., Brizzi G.; Arnone E.; Carlotti M.; Dinelli B. M.; Flaud J. M.; Papandrea E.; Perrin A.; Ridolfi M.

Autors Affiliation: Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA
Univ Bologna, Dipartimento Chim Fis & Inorgan, I-40136 Bologna, Italy
CNR, Ist Sci Atmosfera & Clima, I-40129 Bologna, Italy
Univ Paris 12, Univ Paris 07, Lab Interuniv Syst Atmospher, CNRS, F-94010 Creteil, France

Abstract: We report the first measurement of the isotopic partitioning between stratospheric (HNO3)-N-14 and (HNO3)-N-15. The vertical distribution of the isotope ratio of the two isotopologues of nitric acid was derived using the nu(5) band Q branch of (HNO3)-N-15 that was recently identified in measurements from the MIPAS experiment using newly generated spectral line parameters for the minor isotopologue. Because of the very low intensity of the spectral features adopted for the retrieval, we established an “ad hoc” inversion procedure based on a regularized linear Kalman filter approach. This procedure permits the retrieval of the deviations from the natural (HNO3)-N-15/(HNO3)-N-14 isotope ratio profile, averaged over different latitude bands and time intervals, in the altitude range from 18 to 42 km. The resulting profiles show an overall substantial depletion with height of (HNO3)-N-15, with respect to the natural partitioning, and no significant latitude and time dependence. The developed retrieval procedure can be readily extended to other atmospheric trace gas isotope ratios.

Journal/Review: JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES

Volume: 114      Pages from: D16301-1  to: D16301-12

More Information: The authors are grateful to Simone Ceccherini for fruitful discussions regarding the retrieval approach developed as part of this work. G. Brizzi gratefully acknowledges Kelly Chance for the valuable opportunity of working at CfA and funding through the NASA grant NNG05GO08G. E. Arnone acknowledges funding through the European Community’s Human Potential Programme Marie Curie under contract MERG-CT-2007-209157.
KeyWords: AIRCRAFT MEASUREMENTS; EMISSION-SPECTRA; ATMOS EXPERIMENT; HNO3 PROFILES; MIPAS; FRACTIONATION; CLONO2; SPECTROMETER; STRATOSPHERE; VALIDATION
DOI: 10.1029/2008JD011504