Volatile Organic Compounds and Their Oxidation Chemistry in the Arctic Troposphere

Volatile Organic Compound (VOC) lifetimes depend on chemical structures and therefore vary by molecule. Consequently, analyses of a series of VOC can be applied as a powerful tool for assessing impacts and transport times of polluted air to remote sites. VOC have been measured in flask samples collected at Barrow, AK; Alert, Nunavut; Ny-Alesund, Spitzbergen; and Summit, Greenland, since 2004 within the NOAA-INSTAAR global greenhouse gas and VOC monitoring program. These data are providing new insights into the seasonal and latitudinal trends of the oxidation behavior of the arctic atmosphere. Despite the fact that sources of VOC are small in the arctic environment, ambient background levels and seasonal cycles are larger than in other place on Earth. This behavior is a result of a) the atmospheric import of VOC into the Arctic, and b) from the stark contrast in the seasonal oxidation capacity of the arctic troposphere. In-situ VOC measurements began at Summit in 2008. These much higher time resolution observations (~ 3 hours) allow identification of occurrences and transport times of events bringing air with elevated VOC concentrations to the center of Greenland. Combined, these data provide convincing evidence that VOC in the High Arctic atmosphere are determined by anthropogenic and biomass burning emissions originating from lower latitude regions of the Northern Hemisphere.