Stratosphere‐troposphere exchange: A model and method intercomparison

Meloen, J.; Siegmund, P.; Velthoven, van Pfj Peter; Kelder, H.; Sprenger, Michael; Wernli, Heini; Kentarchos, A. S.; Roelofs, G. J.; Feichter, J.; Land, C.C.; Forster, C.; James, P.; Stohl, Andreas; Collins, William J.; Cristofanelli, Paolo

doi:10.1029/2002jd002274

Cited by 62 publications

(66 citation statements)

References 51 publications

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“…On 29 May the lowest of the layers (below 3.5 km asl) is caused by a stratospheric air intrusion reaching the ground. This intrusion has been well characterized in a number of modeling studies and observations at mountain sites [e.g., Feldmann et al, 1999;Stohl et al, 2000;Cristofanelli et al, 2003;Meloen et al, 2003]. During the first two days of observation a low-ozone layer 2 km wide was observed above the intrusion.…”

Section: Case 1: 29 May To 1 June 1996mentioning

confidence: 89%

Intercontinental transport and its influence on the ozone concentrations over central Europe: Three case studies

et al. 2003

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In this paper we report on a detailed analysis of the first clear observation of ozone import from North America in the free troposphere over central Europe in May 1996 and of two more recent cases of transatlantic transport. The analysis is based on calculations with the FLEXTRA trajectory model and the FLEXPART tracer model and data from Measurements of Ozone and Water Vapor by Airbus In‐Service Aircraft (MOZAIC) flights and North American surface sites. Lidar measurements carried out under conditions of developing anticyclonicity at Garmisch‐Partenkirchen, Germany, consistently yield peak ozone mixing ratios in the middle and upper troposphere between 80 and 110 ppb during the warm season. These layers are traced back to North America by FLEXTRA trajectories. The prevailing transport pathway involves a warm conveyor belt exporting high amounts of ozone, formed during a prefrontal high‐ozone episode, from the central part of the eastern United States to the upper troposphere. The polluted air may enter central Europe above an airstream descending from the stratosphere, thus inverting the normal atmospheric stratification, with stratospheric air at low levels and boundary layer air in the upper troposphere. However, the first two cases studied in this paper show that the export from the eastern United States may arrive over Europe at times prior to the onset of the anticyclonic conditions. Analysis of these cases reveals the complexity of the air export from North America. The ozone maxima occurring during the observational periods are traced back to the planetary boundary layer (PBL) in other source areas in the United States. Some of them are related to entrainments even from source areas beyond North America, either in the stratosphere or in Asia. The third case is quite different in its advection pathway, with almost straight and horizontal advection at 6 to 8 km above sea level starting from the Great Lakes area. A positive correlation between ozone and aerosol in that layer verifies the presence of PBL air. However, the very high ozone mixing ratio (up to 130 ppb) and an anticorrelation of ozone and humidity suggest the entrainment of another component from long‐range transport in the upper troposphere from beyond North America. In two of the case studies the export from the PBL was presumably influenced by large‐scale convection.

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Section: Case 1: 29 May To 1 June 1996mentioning

confidence: 89%

Intercontinental transport and its influence on the ozone concentrations over central Europe: Three case studies

et al. 2003

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“…Meloen et al [2003] and Cristofanelli et al [2003] report on a case study of a deep STT event for which 9 different methods and models (Wei formula, 3 trajectory models, 2 Lagrangian particle models, 1 Eulerian transport model, and 2 GCMs nudged toward analyses) were requested to simulate the transport of an idealized stratospheric tracer with a lifetime in the troposphere of 2 days. Meloen et al [2003] intercompare the model results and Cristofanelli et al [2003] compare them with measurements. It is found that all models captured the STT event, but the magnitudes of the stratospheric tracer fluxes in the troposphere are larger by about a factor of four for the GCMs than for the Lagrangian models.…”

Section: Model Intercomparison and Validationmentioning

confidence: 99%

Stratosphere‐troposphere exchange: A review, and what we have learned from STACCATO

et al. 2003

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[1] This paper provides a review of stratosphere-troposphere exchange (STE), with a focus on processes in the extratropics. It also addresses the relevance of STE for tropospheric chemistry, particularly its influence on the oxidative capacity of the troposphere. After summarizing the current state of knowledge, the objectives of the project Influence of Stratosphere-Troposphere Exchange in a Changing Climate on Atmospheric Transport and Oxidation Capacity (STACCATO), recently funded by the European Union, are outlined. Several papers in this Journal of Geophysical ResearchAtmospheres special section present the results of this project, of which this paper gives an overview. STACCATO developed a new concept of STE in the extratropics, explored the capacities of different types of methods and models to diagnose STE, and identified their various strengths and shortcomings. Extensive measurements were made in central Europe, including the first monitoring over an extended period of time of beryllium-10 ( 10 Be), to provide a suitable database for case studies of stratospheric intrusions and for model validation. Photochemical models were used to examine the impact of STE on tropospheric ozone and the oxidizing capacity of the troposphere. Studies of the present interannual variability of STE and projections into the future were made using reanalysis data and climate models.

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“…In this way also a valuable basis for the quality assurance of numerical models is established. In particular in the frame of the European (EU) projects VOTALP (Vertical Ozone Transport in the ALPS; VOTALP, 2000a, b) and STACCATO (Influence of Stratosphere-Troposphere Exchange in a Changing Climate on Atmospheric Transport and Oxidation Capacity; STACCATO, 2003, http://www.forst.tu-muenchen.de/EXT/ LST/METEO/staccato/) the lidar measurements and the continuous measurements at high-altitude Alpine summit stations have stimulated major efforts in model development, application and validation (e.g., Stohl and Trickl, 1999;Stohl et al, 2000;Zanis et al, 2003;Cristofanelli et al, 2003;Meloen et al, 2003;Roelofs et al, 2003). Many models are, still, far from being quantitative.…”

Section: Introductionmentioning

confidence: 99%

Forecasted deep stratospheric intrusions over Central Europe: case studies and climatologies

et al. 2010

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Abstract. Based on daily predictions of stratospheric air intrusions, obtained from trajectory calculations by ETH Zürich with wind fields from ECMWF forecasts, a high number of measurements with the ozone lidar at IMK-IFU (Garmisch-Partenkirchen, Germany) were carried out in 2001. The lidar measurements show a large variety of rather different cases reflecting the full complexity of intrusion episodes that is not visible in classical case studies. In part, tropopause folds could be fully captured. The frequency of intrusion cases forecasted and verified by vertical sounding or in the in-situ data recorded at the nearby Zugspitze summit (2962 m a.s.l.) exceed that in previous work by more than a factor of two. Three cases mapped with the lidar were selected to validate the results for the corresponding time periods extracted from a one-year run with the new hemispheric version of the chemistry-transport model EURAD. Due to the high spatial resolution chosen for these simulations the agreement with the lidar measurements is satisfactory. The Zugspitze ozone data from 1978 to 2004 were recently filtered by applying different criteria for stratospheric air, based on the 7 Be and humidity measurements. Here, by using the daily model forecasts during the time period 2001-2005, we examine three criteria and determine how well they represent the stratospheric air intrusions reaching the mountain site. Seasonal cycles for the period 2001-2005 were derived forCorrespondence to: T. Trickl (thomas.trickl@kit.edu) the forecasts as well as the intrusion frequency per month for the forecasted intrusions and each of the criteria, distinguishing eight different characteristic transport pathways. In most cases a winter maximum and a summer minimum was obtained, but in the case of cyclonic arrival of intrusions starting over Greenland a late-spring maximum is seen. Two of the filtering criteria examined, based on combining a relativehumidity (RH) threshold of 60% with either a 7 Be threshold of 5.5 mBq m −3 or the requirement for RH≤30% within ±6 h, rather reliably predict periods of deep intrusions reaching the Zugspitze station. An "or" combination of both these criteria yields slightly more cases and covers 77.9% of the intrusions identified. The lack of observations in the complementary 22.1% are mostly explained by overpasses. In this way the long-term trend of stratospheric ozone observed at this site as well as the corresponding ozone budget may be derived on the basis of measurements only. This effort will be the subject of a subsequent publication.

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Stratosphere‐troposphere exchange: A model and method intercomparison

Cited by 62 publications

References 51 publications

Intercontinental transport and its influence on the ozone concentrations over central Europe: Three case studies

Intercontinental transport and its influence on the ozone concentrations over central Europe: Three case studies

Stratosphere‐troposphere exchange: A review, and what we have learned from STACCATO

Forecasted deep stratospheric intrusions over Central Europe: case studies and climatologies

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