Annual gradient maps of precipitation-weighted mean concentrations and depostion are available for NTN. These maps are available in PDF, KMZ, and grid formats.
About the maps
In 2011, the NADP Technical Committee instituted changes in the way NADP annual concentration and deposition maps are produced. It was decided to modify the original map series from a discrete contour map style to a continuous color gradient map style while incorporating an external, highly resolved precipitation dataset.
More information about the process used to create these maps is available.
The old-style isopleth maps through 2009 are available in the NADP Map Archive
NADP's Critical Loads of Atmospheric Deposition Committee has developed a special subset of NTN maps has been developed that highlights the lower end of the concentration and deposition ranges.
The animated maps display the National Trends Network (NTN) concentration and deposition maps from 1985 to 2008 for sulfate, nitrate, and ammonium and the deposition maps for nitrogen from nitrate and ammonium. Flash and PowerPoint versions are available.
If you intend on reprinting any of these maps for use in a publication, please read our Use Conditions.