A History of Reference Surface Observing in Support of Research and Climate, and Progress into the Future, at NOAA's Air Resources Laboratory (ARL)

The groundwork for climate monitoring at ARL began during the National Acid and Precipitation Assessment Program (NAPAP) in the 1980s. The Atmospheric Turbulence and Diffusion Division (ATDD) in Oak Ridge was tasked with developing monitoring methods that could be used to determine the seasonal and annual deposition rates gaseous and aerosol phase of both sulfur and nitrogen compounds throughout the U.S. A network (AirMon-dry) of nearly 15 stations was established in which various atmospheric variables and chemical concentrations were observed and used as input to estimate the dry deposition of sulfur and nitrogen compounds. Following the establishment of this network, another network (AirMon-wet) was initiated which took a subset of sites in the National Atmospheric Deposition Program (NADP) to examine differences on monitoring precipitation chemistry on an event basis versus that of weekly sampling. During that same period, in the mid 1990’s, ARL initiated a network that observed the surface radiation budget at several climatically different locations in the U.S. This network was the baseline system to what now has become the NOAA SURFRAD network that is operated by OAR’s Global Monitoring Laboratory. The network operation experience and instrumentation expertise developed over these years at ARL/ATDD were later tapped by climate scientists from the National Center for Environmental Information (NCEI; and formerly the National Climatic Data Center) is Asheville, N.C to help initiate a reference network to quantify the changing climate across the U.S. for the next fifty years.

This network became what is now the USCRN (U.S. Climate Reference Network). As of this time, the USCRN has 114 stations in the conterminous U.S (CONUS); 25 stations in Alaska; and 2 experimental stations in Hawaii. The final stations will be installed in Alaska over the next few years. In 2008, the program was approached by the National Integrated Drought Information System (NIDIS) based at NOAA, to implement a reference soil moisture/temperature set of instrumentation at five standard soil levels for the stations in the CONUS and that was completed and has been fully operating since 2011. The scientific utility of the USCRN continues to make progress; and in partnership with NCEI we have developed (in 2023) an Aggregate Climate Extremes (ACE) index that will couple both air temperature and precipitation data from about 20 years of USCRN data in the conterminous US to characterize the effects of changes in climate and their relationship to increasing extremes. This will eventually be expanded into Alaska, but the length of the dataset there is not yet sufficiently robust. ARL is also engaged in international climate research activities, such as WMO Solid Precipitation Intercomparison Experiment (SPICE)...