Abstract

Abstract. The CRISTA-NF (Cryogenic Infrared Spectrometers and Telescope for the Atmosphere – New Frontiers) instrument is an airborne infrared limb sounder operated aboard the Russian research aircraft M55-Geophysica. The instrument successfully participated in a large Arctic aircraft campaign within the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) project in Kiruna (Sweden) from January to March 2010. This paper concentrates on the measurements taken during one flight of the campaign, which took place on 2 March in the vicinity of the polar vortex. We present two-dimensional cross-sections of derived volume mixing ratios for the trace gases CFC-11, O3, and ClONO2 with an unprecedented vertical resolution of about 500 to 600 m for a large part of the observed altitude range (≈ 6–19 km) and a dense horizontal sampling along flight direction of ≈ 15 km. The trace gas distributions show several structures, for example a part of the polar vortex and a vortex filament, which can be identified by means of O3–CFC-11 tracer–tracer correlations. The observations made during this flight are interpreted using the chemistry and transport model CLaMS (Chemical Lagrangian Model of the Stratosphere). Comparisons of the observations with the model results are used to assess the performance of the model with respect to advection, mixing, and the chemistry in the polar vortex. These comparisons confirm the capability of CLaMS to reproduce even very small-scale structures in the atmosphere, which partly have a vertical extent of only 1 km. Based on the good agreement between simulation and observation, we use artificial (passive) tracers, which represent different air mass origins (e.g. vortex, tropics), to further analyse the CRISTA-NF observations in terms of the composition of air mass origins. These passive tracers clearly illustrate the observation of filamentary structures that include tropical air masses. A characteristic of the Arctic winter 2009/10 was a sudden stratospheric warming in December that led to a split of the polar vortex. The vortex re-established at the end of December. Our passive tracer simulations suggest that large parts of the re-established vortex consisted to about 45% of high- and mid-latitude air.

Highlights

  • The upper troposphere/lower stratosphere (UTLS) region plays an important role in the climate system (e.g. IPCC, 2007; Riese et al, 2012)

  • We presented high-resolution cross-sections of CFC-11, O3, and ClONO2 derived from the CRISTA-NF measurements in the polar UTLS on 2 March 2010

  • Two filaments with very low CFC-11 volume mixing ratios (VMRs) were observed, which could be analysed in terms of transport and mixing

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Summary

Introduction

The upper troposphere/lower stratosphere (UTLS) region plays an important role in the climate system (e.g. IPCC, 2007; Riese et al, 2012). The composition of the lower Arctic stratosphere is strongly influenced by mixing of polar and mid-latitude air masses, a process that is associated with the occurrence of fine structures and filaments in trace gas distributions. We discuss observations of polar vortex air masses and fine filamentary structures based on twodimensional distributions of the trace gases CFC-11, O3, and ClONO2 with unprecedented vertical resolution for atmospheric limb sounding (Ungermann et al, 2012). The observations were made during a M55-Geophysica flight from Spitsbergen to Kiruna/Sweden on 2 March 2010 in the framework of the European RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions; von Hobe et al, 2013) project During this flight, M55Geophysica encountered an interesting meteorological situation, where a large number of small-scale structures

CRISTA-NF observations
CLaMS simulations
Flight path and meteorological situation
CRISTA-NF retrieval results
Comparison of CRISTA-NF and CLaMS and analysis of the air mass origin
Comparison of trace gases
Air mass origin
Findings
Summary and conclusions

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