Statistical Analysis of USCRN Soil Moisture Observations across the United States

The United States Climate Reference Network (USCRN) is a network of surface climate-monitoring stations starting in 2007 that measure air temperature, precipitation, solar radiation, and soil moisture and temperature at several depths. Run by the National Oceanic and Atmospheric Administration (NOAA), the USCRN was fully deployed in 2007 and now has provided over 10 years of observations. This study explores the USCRN soil moisture measurements and other relevant variables from 102 stations across the continental United States. Daily mean values of soil moisture, soil temperature, rainfall, and maximum air temperature are calculated for each station using data from 2010-2017, as the data prior to 2010 had many missing values. Monthly means and variances were produced and were used to depict the seasonal cycles and their variability. Cluster analysis was applied to the daily mean values of soil moisture to determine soil moisture regimes across the United States. Correlations of daily soil moisture anomalies between stations suggest that 5 cm and 10 cm soil moisture have positive mean correlations for stations separated by less than 300 km.