Heavy ozone distribution in the stratosphere from far‐infrared observations

Abstract

The distribution of isotopically heavy ozone in the stratosphere has been obtained from an analysis of balloon-based high-resolution thermal emission spectra in the far infrared. The mixing ratio profiles of 160160180 and 160180160, retrieved from inversion of several limb sequences of a number of spectral lines in the 39-76 cm -• region, indicate enhancements over the expected values in the 25-to 37-km altitude range. The ratio of total heavy isotopic ozone 500 3 to normal '•80 3 shows enhancements of •45% at 37 km, decreasing to a minimum of ~ 13% at --29 km, and increasing to ~ 18% at 25 km. The results from this work are compared with Mauersberger's (1987) in situ mass spectrometer measurements. INTRODUCTION Isotopic ratios of atoms or molecules often provide valuable information about the past or presently occurring processes inmany branches of science, including astrophysics, geophysics, and atmospheric physics. The isotopic composition of several constituents in the Earth's atmosphere is known to be different from the statistical values on the Earth's surface. The reasons for this isotopic fractionation are diverse and provide information about the chemical and physical processes in the atmosphere. A detailed review of our current understanding of the mechanisms leading to isotopic fractionation in planetary atmospheres has been given by Kaye [1987]. An interest in the problem of photochemical processes controlling the distribution of atmospheric ozone naturally extends to the distribution of ozone isotopes. Heavy ozone is formed in the stratosphere by the reactions and 340 3 --[-hv-• 260 + 280 180 '•-320 2 -•-M • 500 3 -•-M 160-•-340 2 -•-M • 500 3 -•-M (1) (2a) (2b) The suggestion that stratospheric heavy ozone is enhanced owing to the enrichment of 280 produced by a higher photodissociation rate of 340 2 in the Schumman-Runge bands was first made by Cicerone and McCrumb [1980, p. 252]. This suggestion, however, has been contested on two separate bases. First, Kaye and Strobel [1983] and Kaye [1986] have argued that stratospheric heavy ozone concentration depends on the relative time scales for odd oxygen production, destruction, and interconversion, and since the exchange reaction (3 18 0 -•-3202 • 16 0 -•-3402

Retrievals of heavy ozone with MIPAS

“…Since the discovery over 30 years ago, these findings have been confirmed by further mass spectrometer measurements of atmospheric samples (Krankowsky et al, 2007), and by high-resolution spectroscopy using surface-based total-column measurements (Rinsland et al, 1985;Meier and Notholt, 1996), balloon-borne instruments (Abbas et al, 1987;Goldman et al, 1989;Johnson et al, 2000;Haverd et al, 2005), and space-based spectrometers (Irion et al, 1996;Piccolo et al, 2009;Sato et al, 2014). Laboratory research indicated that the observed isotopic enrichment is primarily controlled by unusually strong isotope effects associated with the O 3 formation reaction (Morton et al, 1990):…”

Heavy ozone enrichments from ATMOS infrared solar spectra

“…See IUPAC [1983].) Further stratospheric enrichment of 500 3 has been reported based on mass spectrometry [Mauersberger, 1987], far-infrared emission spectroscopy [Abbas et al, 1987;Carli and Park, 1988], and cryogenic grab-sampling followed by mass spectrometry [Schueler et al, 1990] Table 1 [1986] reported good model fittings to their laboratory spectra, such laboratory measurements would probably produce a constant, corrective scaling of the line intensities (though not necessarily the same amount for both isotopomers), and would not affect the precision of the enrichments described here.…”

Non-Mass-Dependent Isotope Effects in the Formation of O4+

“…Over the past ten years evidence for a non-mass dependent enhancement of 49 Οβ and 50 O3 relative to 48 Οβ in stratospheric ozone has been continually mounting (39)(40)(41). The degree of enhancement appears to increase with altitude with maximum values of about 40% being reported.…”