Cosmogenic radionuclides and ozone at a mountain station at 3.0 km a.s.l.

Reiter, R.; Munzert, K.; Kanter, H. J.; Pötzl, K.

doi:10.1007/bf02273971

Cited by 38 publications

(26 citation statements)

References 8 publications

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“…The overall seasonal cycle (Fig. 12) is less pronounced for Criterion 1 than for forecasts and the other two filtering criteria, in agreement with the findings by Reiter et al (1983) for intrusions with high beryllium values. The asymmetry found for the predicted cases and Criteria 2 and 3 agrees well with the revised FLEXPART model calculation for the Zugspitze summit (Fig.…”

Section: Discussionsupporting

confidence: 87%

“…Nevertheless, the percentiles chosen are related to full-year statistics and, thus, the results are less influenced by short-term variations than those by Elbern et al (1997). A one-year period is sufficiently short in comparison with known periodicities in surface 7 Be (Reiter et al, 1983;Koch and Mann, 1996;Gerasopoulos et al, 2003) in order to account for their influence.…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

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

et al. 2010

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“…Gerasopoulos et al (2001) found at four high-altitude alpine stations that high-7 Be values (above 6 mBq m −3 ) correspond to air masses from the north and high altitudes, as it is characteristic for stratospheric intrusions. Reiter et al (1983) showed that the range of 7 Be values > 7.4 mBq m −3 corresponds to direct stratospheric intrusions near the station, without a long advection path. The third quartile of 7 Be data series at IZO is 8.2 mBq m −3 , and stratospheric air mass intrusions normally reach the ground after considerable mixing with tropospheric air.…”

Section: Upper Troposphere Contributionmentioning

confidence: 95%

“…James et al (2003), with a 15-yr climatology of STT exchange found similar results, concluding that the corridor parallel to the Atlantic coast of the Iberian Peninsula over the ocean down to the Canaries frequently receives stratospheric air. Reiter et al (1983) suggested a 7 Be threshold value of 8 mBq m −3 , above which an air mass probably has stratospheric signature. This value has been used by several to 120 ppbv PVU −1 , which are of the same order as the O 3 /PV max ratios found at IZO.…”

Section: Upper Troposphere Contributionmentioning

confidence: 99%

Assessment of atmospheric processes driving ozone variations in the subtropical North Atlantic free troposphere

et al. 2013

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Abstract. An analysis of the 22-yr ozone (O3) series (1988–2009) at the subtropical high mountain Izaña~station (IZO; 2373 m a.s.l.), representative of free troposphere (FT) conditions, is presented. Diurnal and seasonal O3 variations as well as the O3 trend (0.19 ± 0.05 % yr−1 or 0.09 ppbv yr−1), are assessed. A climatology of O3 transport pathways using backward trajectories shows that higher O3 values are associated with air masses travelling above 4 km altitude from North America and North Atlantic Ocean, while low O3 is transported from the Saharan continental boundary layer (CBL). O3 data have been compared with PM10, 210Pb, 7Be, potential vorticity (PV) and carbon monoxide (CO). A clear negative logarithmic relationship was observed between PM10 and surface O3 for all seasons. A similar relationship was found between O3 and 210Pb. The highest daily O3 values (90th percentile) are observed in spring and in the first half of summer time. A positive correlation between O3 and PV, and between O3 and 7Be is found throughout the year, indicating that relatively high surface O3 values at IZO originate from the middle and upper troposphere. We find a good correlation between O3 and CO in winter, supporting the hypothesis of long-range transport of photochemically generated O3 from North America. Aged air masses, in combination with sporadic inputs from the upper troposphere, are observed in spring, summer and autumn. In summer time high O3 values seem to be the result of stratosphere-to-troposphere (STT) exchange processes in regions neighbouring the Canary Islands. Since 1995–1996, the North Atlantic Oscillation has changed from a predominantly high positive phase to alternating between negative, neutral or positive phases. This change results in an increased flow of the westerlies in the mid-latitude and subtropical North Atlantic, thus favouring the transport of O3 and its precursors from North America, and a higher frequency of storms over North Atlantic, with a likely higher incidence of STT processes in mid-latitudes. These processes lead to an increase of tropospheric O3 in the subtropical North Atlantic region after 1996 that has been reflected in surface O3 records at IZO.

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“…Furthermore, low RH values are also characteristic for air that has descended from the upper troposphere and was warmed adiabatically. High concentrations of the cosmogenic radionuclide Be-7 (t 1/2 = 53.2 days) are also indicative for STTs [Reiter et al, 1983], but Be-7 can be removed by wet scavenging of the carrier aerosol. In addition, because one third of Be-7 is produced in the upper troposphere [Koch and Mann, 1996;Koch et al, 1996;Dutkiewicz and Husain, 1985], it is an ambiguous stratospheric tracer [Zanis et al, 1999;Stohl et al, 2000].…”

Section: Stratospheric Tracers: Experimental and Modeling Approachmentioning

confidence: 99%

Stratosphere‐to‐troposphere transport: A model and method evaluation

et al. 2003

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[1] During the EU-project Influence of Stratosphere-Troposphere exchange in a Changing Climate on Atmospheric Transport and Oxidation Capacity (STACCATO), a combined approach of a measurement network and numerical simulations was used to estimate the strength and frequency of stratosphere-to-troposphere transport (STT) events and their influence on tropospheric chemistry. Measurements of surface ozone, beryllium-7, and beryllium-10 concentrations and meteorological parameters at four European high mountain stations, as well as atmospheric profiles obtained by ozone soundings and a high-resolution lidar, were carried out. In order to simulate STT events, seven different models have been applied by the STACCATO partners. These are two trajectory models (LAGRANTO and FLEXTRA), a Lagrangian transport model (FLEXPART), a Lagrangian chemistry-transport model (STOCHEM), a Eulerian transport model (TM3), and two general circulation models (ECHAM4 and MA-ECHAM4). In order to investigate the strengths and weaknesses of each of these models and to identify the reasons for their discrepancies, a detailed comparison with measured data is presented in this paper. These models provided fluxes and concentrations of a stratospheric tracer, as well as the vertical profiles of ozone and radionuclides for a stratospheric intrusion case study that occurred over Europe in the year 1996. The comparison of the model results with the measurement data and the satellite observations revealed that all the models captured the general behavior of the event. However, great differences were found in the intensity and spatial development of the simulated intrusion event.

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Cosmogenic radionuclides and ozone at a mountain station at 3.0 km a.s.l.

Cited by 38 publications

References 8 publications

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

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

Assessment of atmospheric processes driving ozone variations in the subtropical North Atlantic free troposphere

Stratosphere‐to‐troposphere transport: A model and method evaluation

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