Schrems, Otto
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Schrems, Otto
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Schrems, Otto
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Schrems, O.
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Item-typ:Veröffentlichung, Entwicklung und Anwendung eines Laserablations-ICP-MS-Verfahrens zur Multielementanalyse von atmosphärischen Einträgen in Eisbohrkernen(2001-12-21); ; ; The ice shields of the polar regions are important climate archives and they provide useful insight to the history of the Earth climate back to about 450,000 years. The analysis of element signatures in ice cores yields information about the strength of sources and transport mechanisms for aerosols in the paleoatmosphere as well as about the paleovolcanism. In deep ice layers where annual layers have a thickness of only a few millimetres, it is very difficult to obtain data with high time resolution. The aim of this work reported here was to develop a new method for ice core analysis. The LA-ICP-MS system (Laserablation Inductively Coupled Plasma Mass Spectrometry) is the first one which makes the detection of elements at ultra trace level in a high spatial and thus high time resolution in such thin layers with low risk of contamination possible. By means of a laserbeam at a wavelength of 1064 nm material from the ice surface is ablated. The ablated sample aerosol is introduced to an inductively coupled plasma mass spectrometer where ionisation with subsequent detection occurs. The great advantages of the new technique in comparison to solution analysis are the high spatial resolution of 4 mm that can be gained (independent of ice depth/dense), the fast analysis of total element content (soluble and insoluble components) of about 62 isotopes and a reduced risk of contamination. Ice core samples different ages from Greenland were analysed with the new technique. The results were compared with values from solution analysis as well as available published data. The high spatial resolved analysis show strong inhomogeneous element concentrations along the core axis due to seasonal variations of element deposition. The data from solution analysis (solution ICP-MS and ion chromatography) are in good agreement for many determined elements.Dissertation393 96 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Development of a novel balloon-borne optical sonde for the measurement of ozone and other stratospheric trace gases(2005-10-28); ; ; In the frame of this work, a new small-size balloon-borne sonde was developed. A miniature grating spectrometer in the sonde measures simultaneously the solar spectral irradiance at a wide wavelength range from 200 to 850. As a first application, ozone profiles have been determined by measuring the changes in the spectral irradiance, caused by ozone absorption in the Huggins band. The wide spectral coverage of the spectrometer offers the possibility for measurements of other trace gases which absorb within the wavelength range, e.g. NO2 and BrO. The low weight of the new sonde (1.7 kg), the moderate price, and the autonomous portable telemetry system makes it a very versatile tool for satellite validation and for case studies, which requires a high number of launches.The newly developed sonde works well without temperature stabilisation, even so the spectrometer experiences rather large temperature changes (15 - 20 K) during the ascent through the atmosphere. Laboratory measurements were performed in order to quantify the temperature induced wavelength shift, the absolute irradiance changes, and the dark current behaviour. Based on the laboratory characterisation, inflight corrections could be applied, which compensate the effects of temperature changes. The system was tested in twelve flights and continuously improved. A technical status could be achieved, which guarantees for reliable measurements.For the retrieval of ozone profiles of the irradiance measurements, the analysis algorithm of the ground-based Dobson spectrometer was adapted. The determined ozone profiles were compared to ozone profiles measured by electrochemical sondes and LIDAR. The comparsion shows good agreement within 10% to 20% for altitudes above 15 km. For low solar zenith angles, reliable agreement with comparison measurements even at lower altitudes (8 and 15 km) were achieved. A quality criterion was developed, which allows the evaluation of the calculated ozone profile, independent from the comparison to other measurements.Absorption structures due to NO2 could be identified in the irradiance spectra measured at different altitudes (15 and 35 km). This demonstrated the feasibility of the new instrument to measure other trace gases beside ozone.Dissertation284 115 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Untersuchung der Photooxidantien Wasserstoffperoxid, Methylhydroperoxid und Formaldehyd in der Troposphäre der Antarktis(2001-04-20); ; ; Photooxidants play an important role for the oxidation capacity of the troposphere. The presented work deals with seasonal changes of atmospheric photooxidants like hydrogen peroxide (H2O2), methylhydroperoxide (MHP) and formaldehyde (HCHO). The principal purpose was to follow and quantify the mixing-ratios of these photochemical species for the first time over a complete annual cycle in Antarctica. During two field campaigns at the German Antarctic station Neumayer (overwintering campaign from January 1997 until March 1998 and a shorter campaign from January to March 1999) continuous measurements of atmospheric mixing-ratios were performed. A continuous wet-chemical technique was used for peroxides and formaldehyde sampling and analysis. Species were quantified by fluorescence detection. In order to compare the results and measurements with well-known reaction mechanisms a photochemical box model was applied. The obtained time series show a pronounced seasonal variation with higher values during summer. For the first time atmospheric concentrations of H2O2, MHP and HCHO were documented during polar night in winter. The mixing-ratios were significantly higher than expected due to missing actinic radiation essential for photochemical production. Trajectory analyses and calculations with a three-dimensional model showed that during winter the mixing-ratios of photooxidants are mainly affected by long-range transport in the free troposphere. Investigations during the Antarctic ´´ozone hole period´´ show no significant impact of the increased UV-B radiation on the photooxidants. The findings of this work contribute to a better understanding of the photochemistry of the investigated trace gases in the clean troposphere of Antarctica and provide a useful data record for further photochemical modeling.Dissertation419 195 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Variabilitaet chemischer und physikalischer Parameter des Aerosols in der antarktischen Troposphaere(2003-10-17); ; ; Atmospheric aerosols are chronologically archived in polar ice cores by deposition processes. In principle, investigation of these signals in ice cores offers the opportunity to support the reconstruction of the history of the Earth´s climate. The entry of aerosols to the ice shields is subject of natural variability both at long (e.g. glacial-interglacial) and short (e.g. seasonal) time scales. Information on changes in source strength and transport pathways can be deduced from analysing these signatures. The knowledge of recent aerosol composition and deposition processes is an essential requirement for interpretation of polar ice cores in terms of climate history. This work focuses on spatial and temporal variabilities of the chemical composition of tropospheric aerosol and precipitation, as well as the columnar aerosol optical depth at the German research stations Neumayer, a coastal Antarctic site, and Kohnen located in continental Antarctica in the time period from 1999 to 2002. To obtain information on these variabilities, aerosol and snow samples were investigated regarding their ionic composition at Kohnen Station during austral summer. Investigated ions were MSA:sup:-:/sup: resp. CH3SO3:sup:-:/sup:, Cl:sup:-:/sup:, NO3:sup:-:/sup:, SO4:sup:2-:/sup:, Na:sup: :/sup:, NH4:img:=plus.gif:/img: , K:img:=plus.gif:/img: , Mg:sup:2:/sup::img:=plus.gif:/img: and Ca:sup:2:/sup::img:=plus.gif:/img: . At Neumayer Station the characterisation of the ionic composition and the concentration of some selected trace elements (Li, Sr, Al, Se, Rb, Mn, Fe, V, Cr, Pb and Co) was conducted throughout a year. During austral summer the columnar aerosol optical depth and hence the number and volume distribution of Antarctic aerosol, averaged over the total air column, was quantified both at Neumayer Station and at Kohnen Station by means of sun photometer measurements.Dissertation359 118