[1] During the airborne CONTRACE field experiment carried out in November 2001 a number of polluted layers of North American (NA) origin were observed in the free troposphere over Europe. For the first time, forecasts from a Lagrangian particle dispersion model were used to predict the NA pollution events and to direct a research aircraft very precisely into these polluted layers above Europe. Two of the NA pollution events are investigated here: one in detail (case 19 November) and a second more briefly (case 22 November). An exceptional result was that the first pollution plume could be traced with the model and trace gas measurements (airborne and surface) for a period of one week, from the source region over the eastern United States to its decay over the Alps. On 14–15 November a warm conveyor belt lifted the leading edge of the pollution plume over the eastern United States to the mid troposphere where it remained during the transport over the Atlantic. On 19 November the plume was intersected with the research aircraft over Scandinavia at an altitude between 2 and 4 km. Elevated CO (170), O3 (53), NOy (1.1), acetone (5.0), and SO2 (2.6) mixing ratios (nmol mol−1) were measured. A positive O3-CO correlation was observed in the plume. The observations indicate that the enhanced levels of ozone were already produced near the source region over the eastern United States and not during the transit. In the next days one branch of the plume then turned to the south and descended to ground level over the Alpine region. Elevated O3 (54 nmol mol−1) and CO (168 nmol mol−1) were observed at the mountain site Zugspitze (southern Germany) during two days. At the Arosa Alpine site in Switzerland the highest daily ozone means of November 2001 were observed during this event.

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Intercontinental air pollution transport from North America to Europe: Experimental evidence from airborne measurements and surface observations

A climatology of 7Be at four high-altitude stations at the Alps and the Northern Apennines

Long-term ozone recordings at different altitude levels, conducted in remote areas, can make a valuable contribution to an understanding of the background level of ozone, its periodical variations and possible long-term trends.

Concentration of trace gases in the lower troposphere, simultaneously recorded at neighboring mountain stations Part II: Ozone

Over a period of 12 years, the lower tropospheric content of radionuclides beryllium 7, phosphorus 32, and phosphorus 33 has been measured at a mountain observatory in the Bavarian Alps. These nuclides are generated by cosmic radiation, mainly in the stratosphere. To control the effect of atmospheric nuclear explosions, the heavy metal fallout was determined. Production of these radionuclides is almost independent of solar activity, the influx into the troposphere is subject to this influence. In the exchange between stratosphere and troposphere periodicities are shown that depart from the annual variation. The effect of stratospheric air on the ozone content of the lower troposphere is investigated. The different half-lives of the radionuclides allow an assessment of the stratospheric residence times.

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

On the mean daily and seasonal variations of the vertical ozone profiles in the lower troposphere

The objective of this study is to clarity the contribution of the stratospheric-tropospheric exchange to the balance of the tropospheric ozone. Based on measuring series of the ozone concentration obtained from 1978 to 1981 at three different altitudes (Zugspitze station, 2964 m, Wank station, 1780 m, and valley station Garmisch, 740 m a.s.l.) it can be shown that significant differences do exist in the time behavior of ozone between the valley region and the higher-situated mountain stations. The dependence on meteorological parameters is studied. In series of case studies the vertical distribution on ozone is presented for different source situations. Utility of a filter photometer for measuring total ozone is tested by comparison with Dobson spectrometers. The frequency of stratospheric intrusions is determined by means of the 12-year Be7 measuring series and the seasonal dependence is analyzed. The effect of solar events on the stratospheric ozone profile is shown on the basis of several case studies and the question of causal relationships is discussed. Temporal and spatial variations of the stratospheric aerosol concentrations after eruptions of volcanos St. Helens (1980) and Alaid (1981) are shown by means of lidar measurements. 47 references, 43 figures, 27 tables.

Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides

Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides. Part XI and Part XII. Combined annual report, 1 November 1979-31 January 1982

The balance of the tropospheric ozone is investigated considering the ozone sources with emphasis on tropospheric pollutants and stratospheric-tropospheric exchange processes. The measuring series of ozone concentration from the years 1977-1979 obtained at three different levels of the boundary layer (700, 1800, and 3000 m a.s.l.) have been analyzed. the data have been evaluated in correlation with relevant meteorological parameters, for instance solar radiation. For the different levels various types of ozone sources must be assumed. At the mountain stations prevails influx of stratospheric ozone. In the valley, however, photochemical production must be regarded as main source. A systematic study of ozone profiles obtained by balloon sondes revealed that as a rule after solar flares associated with Forbush effect drastic changes of the ozone profile take place in the lower stratosphere. Then, extremely high maxima of the ozone partial pressure are observed immediately above the tropopause and also intensive influxes of tropospheric air into the stratosphere between 200 and 100 mb. Effects of a modified lidar system on measurements of stratospheric aerosol layers and necessary corrections in evaluating the backscatter profiles are discussed and most recent measuring rresults presented.

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Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides. Technical progress report, November 1, 1979-June 30, 1980

The study of the balance of the tropospheric ozone as a function of atmospheric pollutants and tropospheric transport has been started. Continuous recordings are available of ozone concentration at three levels (3000 m, 1800 m, and 700 m a.s.l.) and of the concentration of the cosmogenic radionuclides /sup 7/Be, /sup 32/P, /sup 33/P, and the CO/sub 2/-concentration. Ozone concentrations >70 ppB have been observed after stratospheric intrusions as well as in consequence of photochemical reactions in the boundary layer. An observation sequence, covering now a period of 20 months, is presented of the stratospheric aerosol layer by means of lidar monitoring. Possible errors in the measuring technique are discussed. A filter photospectrometer for the measurement of the atmospheric total ozone is described, its suitability is checked by a direct intercomparison with a Dobson spectrometer.

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Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides. Technical progress report, 1 November 1977--30 June 1978. [/sup 7/Be, /sup 32/P, /sup 33/P]

R. Reiter

Papers

Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides

Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides. Part XI and Part XII. Combined annual report, 1 November 1979-31 January 1982

Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides

Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides. Technical progress report, November 1, 1979-June 30, 1980

Balance of the tropospheric ozone and its relation to stratospheric intrusions indicated by cosmogenic radionuclides. Technical progress report, 1 November 1977--30 June 1978. [/sup 7/Be, /sup 32/P, /sup 33/P]