Seasonal and geographic variations of methanesulfonic acid in the arctic troposphere

S. M. Li, L. A. Barrie, R. W. Talbot, R. C. Harriss, C. I. Davidson, J. L. Jaffrezo

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

Measurements in the Arctic troposphere over several years show that MSA concentrations in the atmospheric boundary layer, 0.08-6.1 parts per trillion (ppt, molar mixing ration), are lower that those over mid-latitude oceans. The seasonal cycle of MSA at Alert, Canada (82.5°N, 62.3°W), has two peaks of 6 ppt in March-April and July-August and minima of 0.3 ppt for the rest of the year. At Dye 3 (65°N, 44°W) on the Greenland Ice Sheet, a similar seasonal MSA cycle is observed although the concentrations are much lower with a maximum of 1 ppt. Around Barrow, Alaska (71.3°N, 156.8°W), MSA is between 1.0 and 25 ppt in July, higher than 1.5 ± 1.0 ppt in March-April. The mid-tropospheric MSA level of 0.6-1 ppt in the summer Arctic is much lower than about 6 ppt in the boundary layer. At Alert, the ratio of MSA to non-sea-salt (nss) SO42- ranges from 0.02 to 1.13 and is about 10 times higher in summer than in spring. The summer ratios are higher than found over mid-latitude regions and, when combined with reported sulfur isotope compositions from the Arctic, suggest that on average a significant fraction (about 16-23%) of Arctic summer boundary layer sulfur is marine biogenic. The measurements show that the summer Arctic boundary layer has a significantly higher MSA/nss-SO42- ratio than aloft.

Original languageEnglish (US)
Pages (from-to)3011-3024
Number of pages14
JournalAtmospheric Environment Part A, General Topics
Volume27
Issue number17-18
DOIs
StatePublished - Dec 1993
Externally publishedYes

Keywords

  • Aerosol
  • Arctic
  • Greenland ice
  • biogeochemical cycle
  • methanesulfonic acid
  • organic sulfur

ASJC Scopus subject areas

  • Pollution

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