Flux Measurements over Prairie Grasslands in Northern Colorado
The fluxes of nitrogen oxides and ozone have been measured over the prairie grassland of Northern Colorado by eddy correlation. The deposition velocity of ozone varied diurnally. The ozone maximum deposition velocity occurred at around midday, Vd = 0.4 cm s-1, and was zero overnight. The net flux of nitrogen oxides was upward, with a diurnal and a seasonal variation. In early spring there was an upward flux during the day, and zero or a slight downward flux overnight. The daytime NOx fluxes increased from the spring to early summer, as the soil temperature increased. During the summer, moderate rainfall after a few days drought initiated large bursts of upward NOx flux. The average NO2 flux for the period March — July was 1.7 ng N m-2s-l (peak 8.8 ng N m-2s-1), and the average NOx flux for June and July was 5.1 ng N m-2s-l (peak 17.3 ng N m-2s-1).
KeywordsNitrogen Oxide Deposition Velocity Sonic Anemometer Nitrogen Dioxide Eddy Correlation
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