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 and wet deposition monitoring methodologies. For dry deposition, the array is built on the basis of air-surface exchange research stations, originally set up as the `CORE/Satellite Dry Deposition Inferential Methoda array under the National Acid Precipitation Assessment Program (NAPAP). For wet deposition, the program is founded on the Multistate Atmospheric Power Production Pollution Study (MAP3S), previously operated by the Department of Energy but now continuing under NOAA sponsorship. AIRMoN-wet is a research subnetwork 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 hand, and (c) so that research opportunities (such as may result from collocation 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 15 yr, doubtlessly partially attributable to the emissions reductions mandated by the Clean Air Act Amendments of 1990. For the same period, nitric acid vapor concentrations in air indicate a slight increase rather than the decrease seen for sulfur. Published by Elsevier Science Ltd.