Boundary layer O3 dynamics and deposition to tundra during a summer in the Alaskan Arctic
Thursday, 18 December 2014
Atmospheric turbulence quantities, boundary layer O3 levels and deposition to the tundra surface were investigated at Toolik Lake, AK during the 2011 summer season. Beginning immediately after snowmelt a diurnal cycle in ambient O3 developed, and O3 values measured over tundra throughout the summer varied significantly between nighttime minima of 5 ppbv and daytime maxima of 50 ppbv. The mean amplitude of the diurnal cycle in surface O3 following snowmelt was 13 ppbv, far larger than observed at other high Arctic locations. The diurnal cycle is attributed to a combination of surface deposition to the tundra and stable boundary layer conditions at night, and the entrainment of O3 from higher in the atmosphere during increased daytime mixing. The mean O3 deposition velocity during the month of June was 0.11 cm s-1. O3 deposition to tundra exhibited a diurnal cycle, with daytime mean of 0.2 cm s-1 and nighttime mean of 0.08 cm s-1. These values are slightly lower than previously reported summertime deposition velocities in the northern latitudes over tundra or fen, although measurements for comparison were limited.