ARL Participates in USDA Ammonia Flux Experiment
June 18, 2007
Scientists from the Air Resources Laboratory Atmospheric Transport and Diffusion Division (ATDD) in Oak Ridge, Tennessee participated in the second field intensive of the US Department of Agriculture’s Ammonia Flux Experiment, conducted from May 24 through June 5, 2007 near Lillington, NC. The main objective of this effort was to quantify pre- and post-fertilization ammonia fluxes over a 500 acre young maize crop. LaToya Myles and Laureen Gunter of ATDD operated a gradient system utilizing annular denuders to collect ammonia, nitric acid, and sulfur dioxide along with filter packs to collect particulate nitrate and sulfate. Ammonia flux data from ATDD’s gradient system will be compared to data from several state-of-the-art techniques deployed by other research collaborators, including two Pranalytica Nitrolux analyzers and an Ammonia Measurement by Annular Denuder sampling with on-line Analyser system (AMANDA). ATDD also deployed supplementary micrometeorological and fast-response ozone measurements.
The May/June intensive period provided a unique opportunity to study the influence of certain weather phenomena on ammonia flux. The U.S. Drought Monitor of North Carolina classified Lillington (Harnett County) as being in a moderate drought. The drought conditions in North Carolina at the time of the intensive garnered national headlines (“Report: 75% of North Carolina suffering from drought”, USA Today, 5/31/07). The only precipitation that occurred during the intensive came from the remnants of Tropical Storm Barry.
A third intensive measurement period is scheduled for mid-July over the mature maize crop. Data from ATDD’s gradient system will be used to improve ammonia deposition parameterizations in atmospheric models.
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