Climatological features of regional surface air quality from the Atmospheric Integrated Research Monitoring Network (AIRMoN) in the USA

The Atmospheric Integrated Research and Monitoring Network (AIRMoN) of NOAA is a research program aimed at developing and implementing improved dry an d wet deposition monitoring methodologies. For dry deposition, the array is built on the basis of air-surface exchange research stations, originally s et up as the "CORE/Satellite Dry Deposition Inferential Method" array under the National Acid Precipitation Assessment Program (NAPAP). For wet deposi tion, the program is founded on the Multistate Atmospheric Power Production Pollution Study (MAP3S), previously operated by the Department of Energy b ut now continuing under NOAA sponsorship. AIRMoN-wet is a research subnetwo rk of the National Atmospheric Deposition Program. In general, AIRMoN sites are located (a) in locations where changes should be most easily detected, (b) at sites where experienced and interested operators are already on han d, and (c) so that research opportunities (such as may result from collocat ion with other activities) can be maximized. The present analysis concerns the air chemistry data collected as part of the AIRMoN-dry activity. Sulfur data indicate a slow downward trend in air concentrations, at the rate of 3-4%yr(-1) over the last 15yr, doubtlessly partially attributable to the em issions reductions mandated by the Clean Air Act Amendments of 1990. For th e same period, nitric acid vapor concentrations in air indicate a slight in crease rather than the decrease seen for sulfur. Published by Elsevier Scie nce Ltd.