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
Filter
Document type
Keywords
Publisher
Years
  • 1
    facet.materialart.
    Unknown
    Impact of snowpack emissions on deduced levels of OH and peroxy radicals at Summit, Greenland (2002)
    In:  EPIC3Atmospheric Environment, 36, pp. 2523-2534
    Details
    Publication Date: 2019-07-17
    Description: Levels of OH and peroxy radicals in the atmospheric boundary layer at Summit, Greenland, a locationsurrounded by snow from which HOx radical precursors are known to be emitted, were deduced usingsteady-state analyses applied to (OH + HO2 + CH3O2), (OH + HO2), and OHHO2 cycling. The resultsindicate that HOx levels at Summit are significantly increased over those that would result from O3photolysis alone, as a result of elevated concentrations of HONO, HCHO, H2O2, and other compounds.Estimated midday levels of (HO2 + CH3O2) reached 3040 pptv during two summer seasons. Calculated OHconcentrations averaged between 05:00 and 20:00 (or 21:00) exceeded 4 * 10^6 molecules cm^3,comparable to (or higher than) levels expected in the tropical marine boundary layer. These findingsimply rapid photochemical cycling within the boundary layer at Summit, as well as in the upper pore spacesof the surface snowpack. The photolysis rate constants and OH levels calculated here imply that gas-phasephotochemistry plays a significant role in the budgets of NOx, HCHO, H2O2, HONO, and O3, compounds thatare also directly affected by processes within the snowpack.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 2
    facet.materialart.
    Unknown
    Investigation of the role of the snowpack on atmospheric formaldehyde chemistry at Summit, Greenland (2002)
    In:  EPIC3Journal of geophysical research,107(D19),4394
    Details
    Publication Date: 2019-07-17
    Description: Ambient gas-phase and snow-phase measurements of formaldehyde (HCHO) wereconducted at Summit, Greenland, during several summers, in order to understand the roleof air-snow exchange on remote tropospheric HCHO and factors that determine snowpackHCHO. To investigate the impact of the known snowpack emission of HCHO, a gas-phasemodel was developed that includes known chemistry relevant to Summit and that isconstrained by data from the 1999 and 2000 field campaigns. This gas-phase-only modeldoes not account for the high ambient levels of HCHO observed at Summit for severalprevious measurement campaigns, predicting approximately 150 ppt from predominantlyCH4 chemistry, which is ~2550% of the observed concentrations for several years.Simulations were conducted that included a snowpack flux of HCHO based on HCHOflux measurements from 2000 and 1996. Using the fluxes obtained for 2000, thesnowpack does not appear to be a substantial source of gas-phase HCHO in summer. The1996 flux estimates predict much higher HCHO concentrations, but with a strong dielcycle that does not match the observations. Thus, we conclude that, although the flux ofHCHO from the surface likely has a significant impact on atmospheric HCHO above thesnowpack, the timedependent fluxes need to be better understood and quantified. It isalso necessary to identify the HCHO precursors so we can better understand the nature andimportance of snowpack photochemistry.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 3
    Electronic Resource
    Electronic Resource
    Is the Arctic Surface Layer a Source and Sink of NOx in Winter/Spring? (2000)
    Springer
    Journal of atmospheric chemistry 36 (2000), S. 1-22 
    Details
    ISSN: 1573-0662
    Keywords: active nitrogen ; ozone ; radicals ; snow chemistry ; Arctic ; surface layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Measurements of NOx (NO +NO2) and the sum of reactive nitrogenconstituents, NOy, were made near the surface atAlert (82.5°N), Canada during March and April1998. In early March when solar insolation was absentor very low, NOx mixing ratios were frequentlynear zero. After polar sunrise when the sun was abovethe horizon for much or all of the day a diurnalvariation in NOx and NOy was observed withamplitudes as large as 30–40 pptv. The source ofactive nitrogen is attributed to release from the snowsurface by a process that is apparently sensitized bysunlight. If the source from the snowpack is a largescale feature of the Arctic then the diurnal trendsalso require a competing process for removal to thesurface. From the diurnal change in the NO/NO2ratio, mid-April mixing ratios for the sum of peroxyand halogen oxide radicals of ≤10 pptv werederived for periods when ozone mixing ratios were inthe normal range of 30–50 ppbv. Mid-day ozoneproduction and loss rates with the active nitrogensource were estimated to be ∼1–2 ppbv/day and in nearbalance. NOy mixing ratios which averaged only295±66 pptv do not support a large accumulation inthe high Arctic surface layer in the winter and springof 1998. The small abundance of NOy relative tothe elevated mixing ratios of other long-livedanthropogenic constituents requires that reactivenitrogen be removed to the surface during transport toor during residence within the high Arctic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006301029874
    Location Call Number Limitation 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...