Long Term Time Series Analysis of Co-Incident Soil Water Content Sensor at the Marena Oklahoma in Situ Sensor Testbed.

In situ networks are composed of a variety of sensors and installation practices, which confounds the development of a unified reference database, such as the new initiative in the U.S., the National Soil Moisture Network. The Marena Oklahoma In Situ Sensor Testbed (MOISST) was initiated to inter-compare and study sensor performance and limitations. Soil moisture sensors that are deployed in major monitoring networks were included in the study, along with new and emerging technologies, such as the Cosmic Ray Soil Moisture Observing System (COSMOS), Passive/Active Distributed Temperature Sensing System (DTS), and Global Positioning System Reflectometers (GPSR). Four primary in situ stations were installed in May of 2010 and soil moisture was monitored down to a depth of 1 m where possible. The sensors included in the base station configuration included the Stevens Water Hydra Probe, Campbell Scientific 616 and 229, Decagon EC-TM, Delta-T Theta Probe, Acclima, and Sentek EnviroSMART capacitance system. In addition, the Pico TRIME system and additional time domain reflectometry (TDR) systems were deployed when available. Additional sensors were added as they became available, including the Acclima 315, Campbell Scientific 655, and Decagon GS-1. Sensors have also been redeployed as failures occurred. A review of the performance and calibrations of these sensors is performed and conclusions are made.