GLORIA

GEOMAR Library Ocean Research Information Access

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
  • 1
    Electronic Resource
    Electronic Resource
    The 1985 chlorine and fluorine inventories in the stratosphere based on ATMOS observations at 30° north latitude (1992)
    Springer
    Journal of atmospheric chemistry 15 (1992), S. 171-186 
    Details
    ISSN: 1573-0662
    Keywords: Spectroscopic observations ; budgets of chlorine and fluorine ; halogenated gases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The set of high-resolution infrared solar observations made with the Atmospheric Trace Molecule Spectroscopy (ATMOS)-Fourier transform spectrometer from onboard Spacelab 3 (30 April-1 May 1985) has been used to evaluate the total budgets of the odd chlorine and fluorine chemical families in the stratosphere. These budgets are based on volume mixing ratio profiles measured for HCl, HF, CH3Cl, ClONO2, CCl4, CCl2F2, CCl3F, CHClF2, CF4, COF2, and SF6 near 30° north latitude. When including realistic concentrations for species not measured by ATMOS, i.e., the source gases CH3CCl3 and C2F3Cl3 below 25 km, and the reservoirs ClO, HOCl and COFCl between 15 and 40 km (five gases actually measured by other techniques), the 30° N zonal 1985 mean total mixing ratio of chlorine, Cl, was found to be equal to (2.58±0.10) ppbv (parts per billion by volume) throughout the stratosphere, with no significant decrease near the stratopause. The results for total fluorine indicate a slight, but steady, decrease of its volume mixing ratio with increasing altitude, around a mean stratospheric value of (1.15±0.12) ppbv. Both uncertainties correspond to one standard deviation. These mean springtime 1985 stratospheric budgets are commensurate with values reported for the tropospheric Cl and F concentrations in the early 1980s, when allowance is made for the growth rates of their source gases at the ground and the time required for tropospheric air to be transported into the stratosphere. The results are discussed with emphasis on conservation of fluorine and chlorine and the partitioning among source, sink, and reservoir gases throughout the stratosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00053758
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Secular evolution of the vertical column abundances of CHCIF2 (HCFC-22) in the Earth's atmosphere inferred from ground-based IR solar observations at the Jungfraujoch and at Kitt Peak, and comparison with model calculations (1994)
    Springer
    Journal of atmospheric chemistry 18 (1994), S. 129-148 
    Details
    ISSN: 1573-0662
    Keywords: CHCIF2 ; atmospheric composition ; infrared solar observations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Series of high-resolution infrared solar spectra recorded at the International Scientific Station of the Jungfraujoch, Switzerland, between 06/1986 and 11/1992, and at Kitt Peak National Observatory, Tucson, Arizona (U.S.A.), from 12/1980 to 04/1992, have been analyzed to provide a comprehensive ensemble of vertical column abundances of CHCIF2 (HCFC-22; Freon-22) above the European and the North American continents. The columns were derived from nonlinear least-squares curve fittings between synthetic spectra and the observations containing the unresolved 2v 6 Q-branch absorption of CHCIF2 at 829.05 cm−1. The changes versus time observed in these columns were modeled assuming both an exponential and a linear increase with time. The exponential rates of increase at one-sigma uncertainties were found equal to (7.0±0.35)%/yr for the Junfraujoch data and (7.0±0.23)%/yr for the Kitt Peak data. The exponential trend of 7.0%/yr found at both stations widely separated in location can be considered as representative of the global increase of the CHCIF2 burden in the Earth's atmosphere during the period 1980 to 1992. When assuming two realistic vertical volume mixing ratio profiles for CHCIF2 in the troposphere, one quasi constant and the other decreasing by about 13% from the ground to the tropopause, the concentrations for mid-1990 were found to lie between 97 and 111 pptv (parts per trillion by volume) at the 3.58 km altitude of the Jungfraujoch and between 97 and 103 pptv at Kitt Peak, 2.09 km above sea level. Corresponding values derived from calculations using a high vertical resolution-2D model and recently compiled HCFC-22 releases to the atmosphere, were equal to 107 and 105 pptv, respectively, in excellent agreement with the measurements. The model calculated lifetime of CHCIF2 was found equal to 15.6 years. The present results are compared critically with similar data found in the literature. On average, the concentrations found here are lower by 15–20% than those derived from in situ investigations; this difference cannot be explained by the absolute uncertainty of ±11% assigned presently to the infrared remote measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696811
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    facet.materialart.
    Unknown
    Influence of El Nino on atmospheric CO2 over the tropical Pacific Ocean: Findings from NASAs OCO-2 mission (2017)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publication Date: 2017-10-13
    Description: Spaceborne observations of carbon dioxide (CO 2 ) from the Orbiting Carbon Observatory-2 are used to characterize the response of tropical atmospheric CO 2 concentrations to the strong El Niño event of 2015–2016. Although correlations between the growth rate of atmospheric CO 2 concentrations and the El Niño–Southern Oscillation are well known, the magnitude of the correlation and the timing of the responses of oceanic and terrestrial carbon cycle remain poorly constrained in space and time. We used space-based CO 2 observations to confirm that the tropical Pacific Ocean does play an early and important role in modulating the changes in atmospheric CO 2 concentrations during El Niño events—a phenomenon inferred but not previously observed because of insufficient high-density, broad-scale CO 2 observations over the tropics.
    Keywords: Atmospheric Science, Online Only
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    Spaceborne detection of localized carbon dioxide sources (2017)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publication Date: 2017-10-13
    Description: Spaceborne measurements by NASA’s Orbiting Carbon Observatory-2 (OCO-2) at the kilometer scale reveal distinct structures of atmospheric carbon dioxide (CO 2 ) caused by known anthropogenic and natural point sources. OCO-2 transects across the Los Angeles megacity (USA) show that anthropogenic CO 2 enhancements peak over the urban core and decrease through suburban areas to rural background values more than ~100 kilometers away, varying seasonally from ~4.4 to 6.1 parts per million. A transect passing directly downwind of the persistent isolated natural CO 2 plume from Yasur volcano (Vanuatu) shows a narrow filament of enhanced CO 2 values (~3.4 parts per million), consistent with a CO 2 point source emitting 41.6 kilotons per day. These examples highlight the potential of the OCO-2 sensor, with its unprecedented resolution and sensitivity, to detect localized natural and anthropogenic CO 2 sources.
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    The Orbiting Carbon Observatory-2 early science investigations of regional carbon dioxide fluxes (2017)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publication Date: 2017-10-13
    Description: NASA’s Orbiting Carbon Observatory-2 (OCO-2) mission was motivated by the need to diagnose how the increasing concentration of atmospheric carbon dioxide (CO 2 ) is altering the productivity of the biosphere and the uptake of CO 2 by the oceans. Launched on 2 July 2014, OCO-2 provides retrievals of the column-averaged CO 2 dry-air mole fraction ( XCO2 ) as well as the fluorescence from chlorophyll in terrestrial plants. The seasonal pattern of uptake by the terrestrial biosphere is recorded in fluorescence and the drawdown of XCO2 during summer. Launched just before one of the most intense El Niños of the past century, OCO-2 measurements of XCO2 and fluorescence record the impact of the large change in ocean temperature and rainfall on uptake and release of CO 2 by the oceans and biosphere.
    Keywords: Atmospheric Science, Online Only
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    Subsidence, mixing and denitrification of Arctic polar vortex air measured during POLARIS (1999)
    In:  EPIC3Journal of Geophysical Research, 104, pp. 26611-26623
    Details
    Publication Date: 2019-07-16
    Description: We determine the degree of denitrification that occurred during the 1996-1997 Arctic winter using a technique that is based on balloon and aircraft borne measurements of NOy, N2O, and CH4. The NOy/N2O relation can undergo significant change due to isentropic mixing of subsided vortex air masses with extravortex air due to the high nonlinearity of the relation. These transport related reductions in NOy can be difficult to distinguish from the effects of denitrification caused by sedimentation of condensed HNO3. In this study, high-altitude balloon measurements are used to define the properties of air masses that later descend in the polar vortex to altitudes sampled by the ER-2 aircraft (i.e., ~20 km) and mix isentropically with extravortex air. Observed correlations of CH4 and N2O are used to quantify the degree of subsidence and mixing for individual air masses. On the basis of these results the expected mixing ratio of NOy resulting from subsidence and mixing, defined here as NOy**, is calculated and compared with the measured mixing ratio of NOy. Values of NOy and NOy** agree well during most parts of the flights. A slight deficit of NOy versus NOy** is found only for a limited region during the ER-2 flight on April 26, 1997. This deficit is interpreted as indication for weak denitrification (~2-3 ppbv) in that air mass. The small degree of denitrification is consistent with the general synoptic-scale temperature history of the sampled air masses, which did not encounter temperatures below the frostpoint and had relatively brief encounters with temperatures below the nitric acid trihydrate equilibrium temperature. Much larger degrees of denitrification would have been inferred if mixing effects had been ignored, which is the traditional approach to diagnose denitrification. Our analysis emphasizes the importance of using other correlations of conserved species to be able to accurately interpret changes in the NOy/N2O relation with respect to denitrification.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 7
    facet.materialart.
    Unknown
    Halogen occultation experiment ozone channel validation (1996)
    In:  EPIC3Journal of geophysical researchD6, 101, pp. 10217-10240
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 8
    facet.materialart.
    Unknown
    Uncertainty quantification for a global imaging spectroscopy surface composition investigation (2020)
    In:  Remote Sensing of Environment
    Details
    Publication Date: 2020-12-10
    Description: Airborne and orbital imaging spectroscopy can facilitate the quantification of chemical and physical attributes of surface materials through analysis of spectral signatures. Prior to analysis, estimates of surface reflectance must be inferred from radiance measurements in a process known as atmospheric correction, which compensates for the distortion of the electromagnetic signal by the atmosphere. Inaccuracies in the correction process can alter characteristic spectral signatures, leading to subsequent mischaracterization of surface properties. Global observations pose new challenges for mapping surface composition, as varied atmospheric conditions and surface biomes challenge traditional atmospheric correction methods. Recent work adopted an optimal estimation (OE) approach for retrieving surface reflectance from observed radiance measurements, providing the reflectance estimates with a posterior probability. This work incorporates these input probabilities to improve the accuracy of surface feature measurements. We demonstrate this using a generic feature-fitting method that is applicable to a wide range of Earth surface studies including geology, ecosystem studies, hydrology and urban studies. Specifically, we use a probabilistic framework based on generalized Tikhonov-regularized least squares, a rigorous formulation for appropriate weighting of features by their observation uncertainty and leveraging of prior knowledge of material abundance for improving estimation accuracy. We demonstrate the validity of this procedure and quantify the increase in model performance by simulating expected accuracies in the reflectance estimation. To evaluate global uncertainties in mineral estimation, we simulate observations representative of the expected global range of atmospheric water vapor and aerosol levels, and characterize the sensitivity of our procedure to those quantities.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    GFZ OAI
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...