Autor: F. E. Grahek, Kurt G. Anlauf, Ann Louise Sumner, Elliot Atlas, V. Stroud, A. Gallant, Brian A. Ridley, H. Boudries, Frank Flocke, D. Worthy, J. W. Bottenheim, Bryan G. Splawn, James Walega, Paul B. Shepson, Denise D. Montzka, J. Deary
Rok vydání: 2000
Předmět:
Zdroj: Journal of Atmospheric Chemistry. 36:1-22
ISSN: 0167-7764
DOI: 10.1023/a:1006301029874
Popis: 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.
Databáze: OpenAIRE
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