The National Atmospheric Deposition Program (NADP) approved the NADP Precipitation Network in 2023, to formally provide access to the electronic precipitation data. The high-quality precipitation data are gathered using specialized gauges designed for precise measurement under various environmental conditions. The approved gauges are the ETI NOAH IV and the OTT Pluvio Classic, 2L, and S models. These instruments ensure the accuracy and reliability of precipitation data, which are essential for assessing atmospheric deposition and its environmental impacts. To ensure the accuracy of data collected from these gauges, the NADP applies rigorous quality assurance and quality control (QA/QC) protocols. These procedures involve maintenance, calibration, and validation of instruments to ensure that the data meet the highest standards for scientific research.
Metadata
Maps / GIS
Annual Maps
Annual gradient maps of precipitation. These maps are available in PDF and grid format.
Interpolation Methods
The annual composite precipitation surfaces are derived from an adapted version of a high resolution precipitation model developed by the PRISM Climate Group, and supplemented with NADP precipitation observations. PRISM stands for “Parameter-elevation Regression on Independent Slopes Model”. The PRISM modeled precipitation estimates incorporate point observation data, a reliable digital elevation model (DEM), and expert knowledge of complex climatic variables that result in high resolution, continuous, digital grid estimates of total annual precipitation.
NADP modified the original PRISM surfaces by adding in the additional NADP precipitation observations. The annual precipitation surfaces were created by using an inverse distance weighting (IDW) method to calculate a weighted value for every grid cell within a 30 km radius of each NADP precipitation site. The weighted values are calculated using a combination of the PRISM modeled precipitation data, and the NADP observed precipitation values. The weighting function was established so that as you approached the edge of the 30 km radius the values of the weighted grid cells approached that of PRISM. Outside of the 30 km radius the annual precipitation grid cells were populated using only PRISM data.
Compared to generating a precipitation surface using only NADP station data, this process should result in annual precipitation, and subsequently deposition maps with improvements in the estimation of interpolated values, especially in regions of highly complex terrain such as the Rocky Mountains.
Acceptable Use Policy
If you intend on reprinting any of these maps for use in a publication, please read our Use Conditions.
Field Methods
Each National Trends Network (NTN) and Mercury Deposition Network (MDN) site is equipped with an electronic weighing-bucket precipitation gauge that provides a continuous record of rainfall amounts. Rainfall is recorded to the nearest 0.01 inch over 15 minute time periods. The precipitation gauge also monitors the wet deposition collector, recording whether the collector was open during wet periods and closed during dry periods.
Data is transmitted to the processing office in multiple ways. The most common method involves site operators downloading the data from the data logger to a PDA during sample collection. This data is uploaded to the NADP PO on a weekly basis. Alternatively, the site may be connected to a modem or transmitter which can transmit the data automatically at various intervals.
Refer to the Operator Support Information for more information on the various precipitation gauges used in the networks.