As part of the Snow Survey and Water Supply Forecasting (SSWSF) Program, the National Water and Climate Center administers a soil/climate monitoring program consisting of automated data collection sites across the U.S.
The Soil Climate Analysis Network (SCAN) began as a soil moisture/soil temperature pilot project of the Natural Resources Conservation Service in 1991. The system is designed to provide data to support natural resource assessments and conservation activities. The SCAN system focuses on agricultural areas of the U.S. and is composed of over 200 stations. A typical SCAN site monitors soil moisture content at several depths, air temperature, relative humidity, solar radiation, wind speed and direction, liquid precipitation, and barometric pressure. More on SCAN sensors
SCAN automated data collection site
Soil moisture and temperature sensors at a SCAN site. Standard depths are 2, 8, and 20 inches. Optional depths are 4 and 40 inches.
Telemetry and Data Transmission
Data at SCAN sites are collected hourly and stored by a datalogger installed in an electronics enclosure. Depending on the location of the site, data are transmitted back to the Water and Climate Information System using one of several telemetry systems. More on telemetry and data acquisition
Texas A&M University North American Soil Moisture Database