U.S. Climate Reference Network: An Engine for Climate Science

Since the early 2000s, the U.S. Climate Reference Network (USCRN) has been gathering research quality observations of air temperature and precipitation using a redundant configuration of three measurements of each primary variable. This approach was expanded to include soil moisture and soil temperature starting in 2009. In addition, single instruments are gathering important ancillary observations, including relative humidity, global solar radiation, infrared surface temperature, wetness caused by precipitation, and wind speed at gauge height. The stations are owned and maintained by the Atmospheric Turbulence and Diffusion Division (ATDD) of ARL in Oak Ridge, TN, and the observations are archived and made accessible by the National Centers for Environmental Information (NCEI) in Asheville, NC. 114 stations have been installed in the conterminous U.S., 2 stations are in Hawaii, and the 24^th and 25^th stations in Alaska were installed in 2023.

USCRN is sparsely distributed, but plays a critical role in verifying that U.S. air temperatures as measured by the far more numerous networks of the National Weather Service and others collected in the Global Historical Climatology Network are indeed representing climate correctly (Menne et al. 2009). A National Temperature Index derived using both data set shows incredible agreement after many years (Figure 1). In its mission as a reference network, the observations of the three primary variables and several of the ancillary variables have been used to validate satellite estimates of surface air temperature, precipitation, soil moisture, surface temperature, and solar radiation at the surface. Other studies have used USCRN observations for verification of weather and climate models. Others simply use the data as high-quality observational input to studies in various fields. According to Google Scholar, about 400 scholastic works have cited the general reference suggested for those using USCRN data in their studies (Diamond et al. 2013), and about 280 scholastic works have cited the reference suggested for those using USCRN soil moisture/temperature data (Bell et al. 2013).

Many other studies have been conducted directly by the USCRN Science Team to advance measurement science, observation quality control, validation of observation and modelling systems, and production of data products. A few recent highlights have been selected to illustrate these activities.

Bell, J. E., M. A. Palecki, C. B. Baker, W. G. Collins, J. H. Lawrimore, R. D. Leeper, M. E. Hall, J. Kochendorfer, T. P. Meyers, T. Wilson, and H. J. Diamond. 2013 : U.S. Climate Reference Network soil moisture and temperature observations. J. Hydrometeorol. , 14 , 977-988. doi: 10.1175/JHM-D-12-0146.1.

Diamond, H. J., T. R. Karl, M. A. Palecki, C. B. Baker, J. E. Bell, R. D. Leeper, D. R. Easterling, J. H. Lawrimore, T. P. Meyers, M. R. Helfert, G. Goodge, and P. W. Thorne, 2013 : U.S. Climate Reference Network after one decade of operations: status and assessment. Bull. Amer. Meteor. Soc. , 94 , 489-498. doi: 10.1175/BAMS-D-12-00170.1.

Menne, M. J., C. N. Williams, Jr., and M. A. Palecki, 2010 . On the reliability of the U.S. surface temperature record. J. Geophys. Res. , 115 , D11108. doi: 10.1029/2009JD013094.