On the interaction between nitrogen and halogen species in the Arctic polar vortex during THESEO and THESEO 2000

Abstract

[1] Large disagreements between measured and simulated NO 2 have been observed several times in the Arctic polar vortex. Here we report on the comparison of two sets of nighttime balloonborne measurements of the couple (OClO, NO 2 ) with Lagrangian model outputs in order to study the interactions between halogen and nitrogen species. Those measurements were characterized by the simultaneous presence of significant amounts of both species. Large disagreements are observed between modeled and measured NO 2 . Very surprisingly, good agreement can be achieved for OClO in spite of the supposed strong coupling between these two species. The only simultaneous agreement between model and measurements for both species occurs in the case of denoxified conditions, i.e., when there is no interaction between halogen and nitrogen compounds. Furthermore, agreement for OClO cannot be obtained if a source for NO 2 is assumed to fit the measurements of this specie. This result shows that some uncertainties still exist in the interaction between nitrogen and halogen species.

Retrieving the vertical distribution of stratospheric OClO from Odin/OSIRIS limb-scattered sunlight measurements

“…Wahner et al, 1989). This is coherent with the lower OClO peak value observed by Pommereau and Piquard (1994) compared to the maximum values retrieved by Renard et al (1997) and Rivière et al (2003) in the Arctic region. However, no conclusion can be drawn on the relation between these OS OClO carried out in the austral polar region at evening twilight and Arctic observations performed at night.…”

“…Table 8 summarizes the peak value and corresponding altitude, location, date and time of the OClO measurements reported by Pommereau and Piquard (1994), Renard et al (1997), Rivière et al (2003), and for twilight evening OS OClO profiles along orbit 8565 (Fig. 11c).…”

“…11c). The maximum value reported by Rivière et al (2003) in volume mixing ratio as a function of pressure has been converted to number density as a function of altitude by using the temperature and pressure measured in situ during the ascension of the balloon (E. D. Rivière, private communication). The peak values of the OS OClO number density profiles are larger than the peak value detected by Pommereau and Piquard (1994) inside the Arctic polar vortex at twilight.…”

“…It is also important to increase the confidence in the assumed relation between the stratospheric levels of BrO and OClO in the model calculations. Despite the relevance of these profiles, OClO vertical concentrations have been only measured in a few balloon campaigns in northern Scandinavia (e.g., Pommereau and Piquard, 1994;Renard et al, 1997;Payan et al, 1999;Rivière et al, 2003).…”

Simultaneous measurements of OClO, NO<sub>2</sub> and O<sub>3</sub> in the Arctic polar vortex by the GOMOS instrument

“…Since then, other measurements have been performed by using ground-based (Miller et al, 1999), balloon-borne Pommereau and Piquard, 1994;Renard et al, 1997;Riviere et al, 2003) or satellite measurements (Krecl et al, 2006;Wagner et al, 2002). However, the measurements performed using ground-based instruments do not allow the retrieval of vertical distributions.…”