Atmospheric turbulence quantities, boundary layer ozone (O-3) levels, and O-3 deposition to the tundra surface were investigated at Toolik Lake, AK, during the 2011 summer season. Beginning immediately after snowmelt, a diurnal cycle of O-3 in the atmospheric surface layer developed with daytime O-3 maxima, and minima during low-light hours, resulting in a mean amplitude of 13ppbv. This diurnal O-3 cycle is far larger than observed at other high Arctic locations during the snow-free season. During the snow-free months of June, July, and August, O-3 deposition velocities were approximate to 3 to 5 times faster than during May, when snow covered the ground most of the month. The overall mean O-3 deposition velocity between June and August was 0.10cms(-1). The month of June had the highest diurnal variation, with a median O-3 deposition velocity of 0.2cms(-1) during the daytime and 0.08cms(-1) during low-light conditions. These values are slightly lower than previously reported summertime deposition velocities in northern latitudes over tundra or fen. O-3 loss during low-light periods was attributed to a combination of surface deposition to the tundra and stable boundary layer conditions. We also hypothesize that emissions of reactive biogenic volatile organic compounds into the shallow boundary layer may contribute to nighttime O-3 loss.

http://dx.doi.org/10.1002/2015jd023914

Journal Article