• Login
    View Item 
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    •   Home
    • UA Graduate and Undergraduate Research
    • UA Theses and Dissertations
    • Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UA Campus RepositoryCommunitiesTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournalThis CollectionTitleAuthorsIssue DateSubmit DateSubjectsPublisherJournal

    My Account

    LoginRegister

    About

    AboutUA Faculty PublicationsUA DissertationsUA Master's ThesesUA Honors ThesesUA PressUA YearbooksUA CatalogsUA Libraries

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Atmospheric and Ice Core Chemistry of Hydroperoxides in West Antarctica: Links to Stratospheric Ozone and Climate Variability

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    azu_etd_1321_sip1_m.pdf
    Size:
    3.559Mb
    Format:
    PDF
    Description:
    azu_etd_1321_sip1_m.pdf
    Download
    Author
    Frey, Markus Michael
    Issue Date
    2005
    Advisor
    Bales, Roger C.
    Meixner, Thomas
    Committee Chair
    Bales, Roger C.
    Meixner, Thomas
    
    Metadata
    Show full item record
    Publisher
    The University of Arizona.
    Rights
    Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
    Abstract
    Current and past records of hydroperoxides in air, snow and firn of West Antarctica were investigated over 3 field seasons covering >5000 km and 24 sites. Concentrations of methylhydroperoxide (MHP), the only important organic atmospheric hydroperoxide found, were ten times the levels expected based on past photochemical modeling. Between 76 and 90 °S, the snow pack is a net source for hydrogen peroxide (H₂O₂) but not for MHP in summer. There is strong evidence that low stratospheric ozone leads to increases of H₂O₂ at the surface. The modeled sensitivity of H₂O₂ and particularly MHP to nitrogen oxide (NO) shows that atmospheric hydroperoxides help constrain the NO background and thus estimate the past atmospheric oxidation capacity using ice cores. Century-scale H₂O₂ ice core records from 24 locations across the West Antarctic Ice Sheet (WAIS) were used to develop a regional semi-empirical deposition model, with accumulation rate and temperature as parameters. The model fit using long-term average H₂O₂ concentrations is consistent with an existing physically based atmosphere-to-snow transfer model and predicts ‘effective’ annual mean atmospheric H₂O₂ mixing ratios of 1-3 pptv across the region, comparable to observations. Modeled sensitivities suggest that recent Antarctic temperature changes have no noticeable effect on the H₂O₂ record in the interior of WAIS and that accumulation rates dominate the interannual variability of H₂O₂ under the current temperature regime. This leads to the imprint of a large-scale climate signal in the H₂O₂ record, with significant spectral peaks at ENSO-like periodicities (2-7 yr). Validation of results from the new ECMWF reanalysis (ERA-40) using accumulation records from the same cores showed that simulated accumulation rates are too low at 21 of the 22 ice core sites, averaging only 66% (range 34–122%) of the observed accumulation over 1958-2001. Compared to the pre-satellite era (1958-1977) total amounts of accumulation matched better and linear correlations improved after 1978, showing statistical significance at 10 of 22 core sites (0.11 < r < 0.73, p<0.1).
    Type
    text
    Electronic Dissertation
    Degree Name
    PhD
    Degree Level
    doctoral
    Degree Program
    Hydrology
    Graduate College
    Degree Grantor
    University of Arizona
    Collections
    Dissertations

    entitlement

     
    The University of Arizona Libraries | 1510 E. University Blvd. | Tucson, AZ 85721-0055
    Tel 520-621-6442 | repository@u.library.arizona.edu
    DSpace software copyright © 2002-2017  DuraSpace
    Quick Guide | Contact Us | Send Feedback
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.