A stratospheric intrusion at the subtropical jet over the Mediterranean Sea: air-borne remote sensing observations and model results

Weigel, Katja; Hoffmann, Lars; Günther, G.; Khosrawi, Farahnaz; Olschewski, F.; Preusse, Peter; Spang, Reinhold; Stroh, F.; Riese, Martin

doi:10.5194/acp-12-8423-2012

Cited by 22 publications

(23 citation statements)

References 66 publications

(82 reference statements)

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“…For the first time, the layered chemical composition of the lowermost stratosphere close to the subtropical jet is observed two-dimensionally at the resolution of vertically ≈0.5 km and horizontally ≈12.5 km (sampling along the flight-track) by an airborne infrared limb sounder. This paper improves upon work performed by Weigel et al (2012), who evaluated a previous data version of the same flight with considerably less vertical resolution. As a result of an improved retrieval scheme, the cross sections exhibit a much improved vertical resolution for the stratospheric trace gases ozone and nitric acid (see Appendix A), which in turn allows for the identification of previously non-resolvable fine-scale filaments in the extratropical UTLS.…”

Section: Introductionmentioning

confidence: 51%

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Filamentary structure in chemical tracer distributions near the subtropical jet following a wave breaking event

et al. 2013

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Abstract. This paper presents a set of observations and analyses of trace gas cross sections in the extratropical upper troposphere/lower stratosphere (UTLS). The spatially highly resolved (≈0.5 km vertically and 12.5 km horizontally) cross sections of ozone (O 3 ), nitric acid (HNO 3 ), and peroxyacetyl nitrate (PAN), retrieved from the measurements of the CRISTA-NF infrared limb sounder flown on the Russian M55-Geophysica, revealed intricate layer structures in the region of the subtropical tropopause break. The chemical structure in this region shows an intertwined stratosphere and troposphere. The observed filaments in all discussed trace gases are of a spatial scale of less than 0.8 km vertically and about 200 km horizontally across the jet stream. Backward trajectory calculations confirm that the observed filaments are the result of a breaking Rossby wave in the preceding days. An analysis of the trace gas relationships between PAN and O 3 identifies four distinct groups of air mass: polluted subtropical tropospheric air, clean tropical upper-tropospheric air, the lowermost stratospheric air, and air from the deep stratosphere. The tracer relationships further allow the identification of tropospheric, stratospheric, and the transitional air mass made of a mixture of UT and LS air. Mapping of these air mass types onto the geo-spatial location in the cross sections reveals a highly structured extratropical transition layer (ExTL). Finally, the ratio between the measured reactive nitrogen species (HNO 3 + PAN + ClONO 2 ) and O 3 is analysed to estimate the influence of tropospheric pollution on the extratropical UTLS.In combination, these diagnostics provide the first example of a multi-species two-dimensional picture of the inhomogeneous distribution of chemical species within the UTLS region. Since Rossby wave breaking occurs frequently in the region of the tropopause break, these observed fine-scale filaments are likely ubiquitous in the region. The implications of the layered structure for chemistry and radiation need to be examined, and the representation of this structure in chemistry-climate models is discussed.

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Section: Introductionmentioning

confidence: 51%

“…A detailed description of the first retrieval of this set of measurements is given by Weigel et al (2012). Ungermann et al (2012) improved this setup by employing a more accurate line-of-sight determination and a finer retrieval grid.…”

Section: Appendix a Retrievalmentioning

confidence: 99%

Filamentary structure in chemical tracer distributions near the subtropical jet following a wave breaking event

et al. 2013

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“…The same phenomenon has been deduced from ship-borne ozone observations in the Western Mediterranean (Velchev et al, 2011). The Mediterranean is subject to episodes of import of UTLS ozone-enriched air through tropopause folds formed along the sub-tropical jet (Weigel et al, 2012), or due to the propensity for cut-off low formation in the region (Nieto et al, 2005). The region is also subject to conditions favouring enhanced photochemical activity, as well as the long-range import of air masses from other Northern Hemisphere regions of ozone precursor emission.…”

Section: Introductionmentioning

confidence: 65%

The Mediterranean summertime ozone maximum: global emission sensitivities and radiative impacts

et al. 2013

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The Mediterranean troposphere exhibits a marked and localised summertime ozone maximum, which has the potential to strongly impact regional air quality and radiative forcing. The Mediterranean region can be perturbed by long-range pollution import from Northern Europe, North America and Asia, in addition to local emissions, which may all contribute to regional ozone enhancements. We exploit ozone profile observations from the Tropospheric Emission Spectrometer (TES) and the Global Ozone Monitoring Experiment-2 (GOME-2) satellite instruments, and an offline 3-D global chemical transport model (TOMCAT) to investigate the geographical and vertical structure of the summertime tropospheric ozone maximum over the Mediterranean region. We show that both TES and GOME-2 are able to detect enhanced levels of ozone in the lower troposphere over the region during the summer. These observations, together with surface measurements, are used to evaluate the TOMCAT model's ability to capture the observed ozone enhancement. The model is used to quantify sensitivities of the ozone maximum to anthropogenic and natural volatile organic compound (VOC) emissions, anthropogenic NO_x emissions, wildfire emissions and long-range import of ozone and precursors. Our results show a dominant sensitivity to natural VOC emissions in the Mediterranean basin over anthropogenic VOC emissions. However, local anthropogenic NO_x emissions are result in the overall largest sensitivity in near-surface ozone. We also show that in the lower troposphere, global VOC emissions account for 40% of the ozone sensitivity to VOC emissions in the region, whereas, for NO_x the ozone sensitivity to local sources is 9 times greater than that for global emissions at these altitudes. However, in the mid and upper troposphere ozone is most sensitive to non-local emission sources. In terms of radiative effects on regional climate, ozone contributions from non-local emission sources are more important, as these have a larger impact on ozone in the upper troposphere where its radiative effects are larger, with Asian monsoon outflow having the greatest impact. Our results allow improved understanding of the large-scale processes controlling air quality and climate in the region of the Mediterranean basin

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“…Ungermann et al, 2010Ungermann et al, , 2013, a further development of JURASSIC, which was successfully used to analyse measurements from various satellites and airborne limb-emission measurements (e.g. Hoffmann et al, 2008;Hoffmann and Alexander, 2009;Weigel et al, 2012). The main targets of the retrieval are CFC-11, O 3 , ClONO 2 , HNO 3 , H 2 O, and CCl 4 .…”

Section: Crista-nf Observationsmentioning

confidence: 99%

Observations of filamentary structures near the vortex edge in the Arctic winter lower stratosphere

Kalicinsky

Grooß²,

Günther³

et al. 2013

Atmos. Chem. Phys.

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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, O 3 , and ClONO 2 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 O 3 -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.

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A stratospheric intrusion at the subtropical jet over the Mediterranean Sea: air-borne remote sensing observations and model results

Cited by 22 publications

References 66 publications

Filamentary structure in chemical tracer distributions near the subtropical jet following a wave breaking event

Filamentary structure in chemical tracer distributions near the subtropical jet following a wave breaking event

The Mediterranean summertime ozone maximum: global emission sensitivities and radiative impacts

Observations of filamentary structures near the vortex edge in the Arctic winter lower stratosphere

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