Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 11
    Electronic Resource
    Electronic Resource
    Groundbased Doas UV/visible measurements at Kiruna (Sweden) during the sesame winters 1993/94 and 1994/95. (1998)
    Springer
    Journal of atmospheric chemistry 30 (1998), S. 141-162 
    Details
    ISSN: 1573-0662
    Keywords: Zenith sky observations of stratospheric O3, NO2, OClO and BrO
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Zenith sky observations of O3, NO2, OClO and BrO are reported, which were performed at Kiruna (67.9°N, 21.1°E) within the SESAME winters 1993/1994 and 1994/95. For both winters large total amounts of OClO were observed inside the polar vortex at twilight, indicating the degree and the temporal variation of the halogen activation of the polar stratosphere. Occasionally OClO could also be observed outside the polar vortex, most likely due to export of halogen activated vortex air masses into the ambient stratosphere. BrO could also be detected in winter 1994/95, with the largest slant column amounts (5·1014/cm2) occuring in the polar vortex in mid-winter. Similar abundances of stratospheric BrO were observed at dusk and dawn, for both, air masses inside and outside the vortex. This observation is in reasonable agreement with previous studies on stratospheric BrO (observations and models) of Wahner et al. (1992), Arpag et al. (1994), Krug et al. (1996), and Lary et al. (1996a,b), but partly in disagreement with those of Solomon et al. (1989), Fish et al. (1995), and Sessler et al. (1996).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005810732347
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Deuterium, Oxygen-18, and Tritium as Tracers for Water Vapour Transport in the Lower Stratosphere and Tropopause Region (1998)
    Springer
    Journal of atmospheric chemistry 30 (1998), S. 25-47 
    Details
    ISSN: 1573-0662
    Keywords: Isotopic composition of H2O ; water vapour transport ; stratospheric-tropospheric exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Simultaneous measurements of the three rare isotopes Deuterium (D), Tritium (T), and Oxygen-18 (18O) in water vapour were made for the first time in the vicinity of the northern hemisphere tropopause. In contrast to expectation, high D/H and 18O/16O ratios, but relatively low T/H ratios, were found within the lowermost stratosphere. Since water vapour in the low-latitude upper troposphere shows a similar isotopic signature, we conclude that in the mid-latitudes considerable amounts of tropospheric water vapour are injected into the lowermost stratosphere, probably resulting in a hydration of the lower stratosphere. In addition, T can serve as tracer for precipitation of water containing stratospheric aerosol particles, because the T/H ratio in stratospheric water vapour is orders of magnitude higher than in the upper troposphere. Thus, even a small contribution of water of stratospheric origin should be detectable in the tropopause region. In our measurements performed in the Arctic we did not find isotopic evidence for sedimentation of PSC particles down to the tropopause. This may be caused by the low spatial and temporal coverage of our observations; however, it may also be due to the much weaker wintertime dehydration of the Arctic vortex compared to the Antarctic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005896532640
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Measurements of tropospheric OH concentrations: A comparison of field data with model predictions (1987)
    Springer
    Journal of atmospheric chemistry 5 (1987), S. 185-216 
    Details
    ISSN: 1573-0662
    Keywords: OH-radicals ; troposphere ; long path absorption spectroscopy ; sensitivity study ; formaldehyde ; measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048859
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Observation of the Stratospheric NO2 Latitudinal Distribution in the Northern Winter Hemisphere (1999)
    Springer
    Journal of atmospheric chemistry 32 (1999), S. 101-120 
    Details
    ISSN: 1573-0662
    Keywords: stratospheric NO2 ; latitudinal cross section
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract During a series of flights in the winters 1991/92 to 1994/95 total stratospheric NO2 was measured by means of the DOAS (Differential Optical Absorption Spectroscopy) technique on board a C160 (Transall) aircraft. In an area covering 60°W to 60°E, and 16°N to 86°N, the total stratospheric NO2 was observed to vary markedly with latitude and season (winter and spring). In the mid-winter Arctic vortex extremely low total stratospheric NO2 (〈 3.1014/cm2) was always found, generally larger amounts of NO2 occurred outside the vortex in winter and towards the spring both inside and outside the vortex. This behaviour of stratospheric NO2 can be explained by the denoxification of the wintertime polar stratosphere. Ambient to the vortex in mid-winter however, ‘sudden’ increases of total stratospheric NO2 by about a factor of 3 were observed. These sudden increases in stratospheric NO2 coincide with a change in the wavenumber 2 of the geopotential height at 60°N, which indicates that most likely the events are caused by planetary waves efficiently transporting air masses rich in NOx from lower to higher latitudes. The monitoring of stratospheric NO2, during latitudinal traverses ranging from the Arctic (80°N) to the Subtropics (18°N) in spring also unexpectedly showed a large variability in total stratospheric NO2 at mid-latitudes. Since photochemistry almost certainly can be excluded, it is proposed that the observed variability may be due to the planetary wave activity of the stratospheric surf zone, known to dynamically connect the tropical and the polar stratosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006033625952
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Observation of Filterable Bromine Variabilities During Arctic Tropospheric Ozone Depletion Events in High (1hour) Time Resolution (1999)
    Springer
    Journal of atmospheric chemistry 34 (1999), S. 39-54 
    Details
    ISSN: 1573-0662
    Keywords: tropospheric ozone ; atmospheric aerosol particles ; halogen chemistry ; Arctic regions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The halogen ions Br- and Cl- together with NO3 -, SO4 =, MSA- (methane sulfonate), Na+ and NH4 + were analysed by ion chromatography in extracts of more than 800 aerosol cellulose filter samples taken at Ny Ålesund, Svalbard (79°N, 12°E) in spring 1996 (March 27 - May 16) within the European Union project ARCTOC (Arctic Tropospheric Ozone Chemistry). Anticorrelated variations between f-Br (filterable bromine, i.e. water soluble bromine species that can be collected by aerosol filters) and ozone within the arctic troposphere were evaluated at a resolution of 1 or 2 hours for periods with depleted ozone and 4 hours at normal ozone. A mean f-Br concentration of 11 ng m-3 (0.14 nmol m-3) was observed for the whole campaign, while maximum concentrations of 80 ng m-3 (1 nmol m-3) were detected during two total O3-depletion events (O3 drop to mixing ratios below the detection limit of 〈 2 ppb). Anticorrelation between f-Br and O3 was also seen during minor O3-depletion episodes (sudden drop in O3 by at least 10 ppb, but O3 still exceeding the detection limit) and even for ozone variations near its background level (40-50 ppb). A time lag of about 10 hours between the change of ozone and of f-Br concentrations could only be found during a total ozone depletion event, when f-Br reached its maximum values several hours after ozone was totally destroyed. Bromine oxide (BrO) concentrations, measured by DOAS (Differential Optical Absorption Spectroscopy), and f-Br showed a coincident variability during almost the entire campaign (except in the case of total O3-loss). Frequently enhanced anthropogenic nitrate and sulphate concentrations were observed during O3-depletion periods. At O3 concentrations 〈 10 ppb sulphate and nitrate exceed their typical mean level by 54% and 77%, respectively. This may indicate a possible connection between acidity and halogen release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006217001008
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    High resolution spectral features of a series of aromatic hydrocarbons and BrO: Potential interferences in atmospheric OH-measurements (1991)
    Springer
    Journal of atmospheric chemistry 12 (1991), S. 287-298 
    Details
    ISSN: 1573-0662
    Keywords: Naphthalene ; bromine oxide ; differential absorption spectroscopy ; OH measurement ; interferences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Naphthalene (C10H8), several other hydrocarbons, mostly derivates of naphthalene, and bromine oxide (BrO) were analyzed for narrow band (≤0.01 nm) absorption lines in the wavelength range between 307.7 and 308.3 nm to study their potential impact on OH radical measurements by differential absorption spectroscopy. Only naphthalene showed narrow band absorption lines in this wavelength region. From nine naphthalene lines the differential absorption cross-section σ′ was determined. The strongest naphthalene line at 308.002 nm is close to the Q 1(2) OH line, but about a factor of 200 weaker (σ′=(65.2±15.3)×10-20 cm2/molec). The corresponding detection limit for naphthalene is about 15 ppt. We re-evaluated some spectra of our OH measurement campaign in July 1987 with respect to naphthalene and obtained an upper limit of 30 ppt for its concentration. BrO was recorded in the larger wavelength interval between 307.7 and 308.7 nm. Structured absorptions were only observed at wavelengths above 308.2 nm and no significant structures were found in the vicinity of the Q 1(2) and Q 1(3) OH lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048077
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Reactive Halogen Species in the Mid-Latitude Troposphere — Recent Discoveries (2000)
    Springer
    Water, air & soil pollution 123 (2000), S. 229-244 
    Details
    ISSN: 1573-2932
    Keywords: bromine ; chlorine ; halogen species ; spectroscopy ; tropospheric chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract While the role of reactive halogen species (e.g., Cl, Br) in the destruction of the stratospheric ozone layer is well known, up to now it was assumed that these tropospheric halogen events were confined to the polar regions during springtime. However, during the last few years, significant amounts of BrO and Cl-atoms were also found in the Arctic and Antarctic boundary layer. Recently, even higher BrO mixing ratios (up to 90 ppt) were detected by optical absorption spectroscopy (DOAS) in the Dead Sea basin during summer. In addition, evidence is accumulating that BrO (at levels around 1–2 ppt) is also occurring in the free troposphere (in polar regions as well as at mid- latitudes). In contrast to the strategosphere, where halogens are released from species which are very long lived in the troposphere, likely sources of boundary layer Br and Cl are oxidation of sea-salt halides, while precursors of free tropospheric BrO probably are short-lived organo-halogen species. In addition, it is well possible that boundary layer halogens, in particular bromine, may 'leak out' to the free troposphere and thus could have a regional or even more widespread effect. At the levels suggested by the available measurements, reactive halogen species have a profound effect on tropospheric chemistry: In the boundary layer during 'halogen events' ozone is usually completely lost within hours or days — the 'Polar Tropospheric Ozone Hole'. In the free troposphere the effective O3- losses due to halogens could be comparable to the known photochemical O3 destruction. Further interesting consequences include the increase of OH levels and (at low NOX) the decrease of the HO2/OH ratio in the free troposphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005267321567
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Ein Instrument zur spektroskopischen Spurenstoffmessung in der Atmosphäre (1984)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 317 (1984), S. 309-313 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Beschrieben wird ein relativ einfach aufgebautes Gerät zur Identifikation und Konzentrationsbestimmung von atmosphärischen Spurenstoffen mittels Langpfad-Absorptionsspektroskopie im sichtbaren und ultravioletten Spektralbereich. Ein voreingestellter Wellenlängenbereich wird mit hoher Wiederholfrequenz (∼ 100 Hz) abgetastet. In über einige zehntausend Abtastungen gemittelten Spektren sind Molekülbanden mit optischen Dichten von unter 10−4 noch nachweisbar. Bei 10 km Lichtweg in der freien Atmosphäre werden folgende Nachweisgrenzen erreicht: SO2: 17 ppt (1ppt = 1 Teil in 1012); NO2: 100 ppt; NO3: 0.5 ppt; HNO2: 20ppt; O3: 2100ppt; CH2O: 120 ppt.
    Notes: Summary A relatively simple instrument for the detection and measurement of atmospheric trace constituents by longpath absorption spectroscopy in the visible and UV spectral ranges is described. A selected wavelength interval is scanned with high repetition rate (∼ 100 Hz). After averaging over several ten thousand scans molecular absorption bands with optical densities below 10−4 can be detected. Using a 10-km lightpath the following detection limits are reached: SO2: 17ppt(1 ppt = 1 part in 1012); NO2: 100 ppt; NO3: 0.5 ppt; HNO2: 20 ppt; O3: 2100 ppt; CH2O: 120 ppt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00494483
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Spectroscopic measurement of free radicals (OH, NO3) in the atmosphere (1991)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 340 (1991), S. 633-637 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Due to their high chemical reactivity free radicals are the driving force for most chemical processes in the atmosphere, this is true, in particular, for OH- and NO3-radicals. Thus, knowledge of the concentration of those species in the atmosphere is a key requirement for the investigation of atmospheric chemistry. The low concentration of free radicals makes measurements particularly difficult, however. Among several techniques applied to the problem UV/visible differential absorption spectroscopy appears to be the most successful for the observation of OH and NO3. Detection limits of the order of 106 and 107 molec/cm3, respectively, have been reached, which are sufficiently low to resolve diurnal profiles of both species. The relative importance of both radicals in the NOx to nitric acid conversion is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00321525
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...