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Browsing Research publications by Author "5c9598cfc91a53fabc2c7629e0c94b63"
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Item Open Access Measurements of C2-C5 Hydrocarbons Over the North Atlantic(1981) Rudolph, J.; Ehhalt, D.H.Latitudinal distributions of ethane, propane, propene, and acetylene in air over the Atlantic from 48°N to 4°S are reported. In addition, measurements of saturated and unsaturated hydrocarbons (C2-C5) at low latitudes and from 55°N to 80°N are presented. The mixing ratios of ethane, propane, and acetylene were found to vary systematically between a few tenths of a ppb and a few ppb. The alkene and higher alkane (C4 and C5) mixing ratios were found to be in the ppt range. The data are discussed with respect to the source distributions and atmospheric lifetimes of the different hydrocarbons.Item Open Access Measurements of selected C2-C5 hydrocarbons in the background troposphere: Vertical and latitudinal variations(Springer Netherlands, 1985) Ehhalt, D.H.; Rudolph, J.; Meixner, F.X.; Schmidt, UMeridional cross sections of the concentration of light hydrocarbons are reported. They were obtained from 20. April to 10. May, 1980, during the French research flight STRATOZ II, and cover the latitudes between 60° N and 60° S and the altitudes between 800 mb and 200 mb. The mixing ratios of ethane, ethene, acetylene, propane, propene, n-butane, i-butane, n-pentane, and i-pentane range between 2.0 and 0.02 ppb. Globally, a decrease in concentration with increasing altitude and -in most cases-with decreasing latitude is observed. In addition the 2-dimensional concentration fields show structures of different scales. In particular, isolated maxima of high concentrations are found in the upper troposphere. They point to fast vertical transport between the boundary layer and the upper troposphere. In the present case these maxima seem to be correlated with large scale meteorological systems, such as low pressure regions or the Inter Tropical Convergence Zone. It is argued that the NMHC provide a set of tracers well suited to the detection of fast vertical transport.Item Open Access Measurements of Tropospheric OH Concentrations: A Comparison of Field Data with Model Predictions(Springer Verlag, 1987) Perner, D.; Platt, U.; Trainer, M.; Hübler, G.; Drummond, J.; Junkermann, W.; Rudolph, J.; Schubert, B.; Volz, A.; Ehhalt, D.H.; Rumpel, K.J.; Helas, G.Using long path UV absorption spectroscopy we have measured OH concentrations close to the earth's surface. The OH values observed at two locations in Germany during 1980 through 1983 range from 0.7×106 to 3.2×106 cm-3. Simultaneously we measured the concentrations of O3, H2O, NO, NO2, CH4, CO, and the light non methane hydrocarbons. We also determined the photolysis rates of O3 and NO2. This allows calculations of OH using a zero dimensional time depdendent model. The modelled OH concentrations significantly exceed the measured values for low NO x concentrations. It is argued that additional, so far unidentified. HO x loss reactions must be responsible for that discrepancy.Item Open Access New Tropospheric OH Measurements(1988) Platt, U.; Rateike, M.; Junkermann, W.; Rudolph, J.; Ehhalt, D.H.New field measurements of atmospheric OH radicals by laser long-path absorption spectroscopy are reported: In the Black Forest, diurnal profiles of OH radical concentrations ranging up to 8.7 × 106 cm−3 have been observed during June 1984. Simultaneous measurements of other trace gases, photolysis frequencies, and meteorologic parameters were also made to allow comparison of observed OH levels with model calculations.Item Open Access Vertical column abundances and seasonal cycle of acetylene, C2H2, above the Jungfraujoch station, derived from IR solar observations(Springer-The Netherlands, 1991) Zander, R.; Rinsland, C.P.; Ehhalt, D.H.; Rudolph, J.; Demoulin, Ph.Monthly mean total vertical column abundances of acetylene have been determined from series of infrared solar spectra recorded at the Jungfraujoch station, Switzerland, between June 1986 and April 1991. The data have been obtained by nonlinear least-squares fittings of the 5 band R19 transition of C2H2 at 776.0818 cm-1. The average of 22 monthly mean total vertical columns of C2H2 retrieved during that time interval of almost 5 years was found to be equal to (1.81±0.12)×1015 molec/cm2, which corresponds to an average mixing ratio of (0,22±0.013) ppbv (parts per billion by volume) in a troposphere extending from the altitude of the station (3.58 km), up to 10.5 km. Despite the large variability found from year to year, a least-squares sine fit to the data reveals a seasonal variation with an amplitude of about ±40% of the mean; the maximum occurs during mid-winter and the minimum in the summer. The present results are compared critically with similar in-situ data found in the literature. A sinusoidal fit to all such free troposphere measurements made in-situ between 30°N and 60°N indicates good agreement in shape and phase with the seasonal variation derived above the Jungfraujoch, but their average column abundance, 2.3×1015 molec/cm2, is about 30% higher; this difference is explained on the basis of non-upwelling meteorological conditions generally prevailing during ground-based remote solar observations.Item Open Access Vertical profiles of acetylene in the troposphere and stratosphere(Springer Netherlands, 1984) Rudolph, J.; Ehhalt, D.H.; Khedim, A.Stratospheric measurements of acetylene up to altitudes of 30 km are presented. The air samples were collected during three different balloon flights, two of them at 44°N, one at 32°N using balloon borne, liquid neon-cooled, cryosamplers. Their acetylene concentration was measured in the laboratory by flame ionisation gaschromatography. The different profiles at 32°N and 44°N are discussed with respect to possible vertical exchange processes and compared with published model calculations.Item Open Access Vertical Profiles of Ethane and Propane in the Stratosphere(AGU, 1981) Rudolph, J.; Ehhalt, D.H.; Tonnissen, A.Stratospheric measurements of the C2H6 mixing ratio up to 30 km and of the C3H8 mixing ratio up to 18 km altitude are reported. The observed vertical gradient of C2H6 is much weaker than that calculated from a one-dimensional steady state model, indicating lower concentrations of atomic chlorine in the lower stratosphere than those predicted by models. From the measured C2H6 profile a tentative estimate for the Cl concentration is derived.