Field Evaluation of a New Sensor for Near-Surface Critical Zone Soil Moisture in Continuous Spatial Profile

Abstract:

A new sensor technology, the Profile Resolving In-situ Soil Moisture Sensor (PRISMS), offers the potential to advance understanding of coupled biogeochemical and hydrologic processes in the near subsurface critical zone by acquiring continuous vertical profiles of near surface soil moisture. We present results of comparing PRISMS acquired soil moisture data to data from arrays of conventional TDR soil moisture probes installed at the Tropical Responses to Altered Climate Experiment (TRACE) site in Luquillo, Puerto Rico.

Tropical forests exchange more carbon dioxide with the atmosphere than any other biome on Earth. In the next 20 years, the tropics will experience unprecedented warming, yet there is exceedingly high uncertainty about their potential responses to this imminent climatic change. TRACE is being conducted to help elucidate how tropical forests will respond to increasing temperatures, by examining critical processes in the most biogeochemically active ecosystem components of tropical forests (i.e., leaves, roots, soil microbes). These processes are coupled to subsurface hydrology which PRISMS monitors by providing continuous spatial profiles of soil moisture content.

Six PRISMS probes were installed in and around two experimental plots in the TRACE, alongside vertical arrays of conventional TDR soil moisture probes that perform discrete volume averaged measurements. Data are being collected to validate the performance of the new technology. Preliminary results from the continuously profiling 1-meter long PRISMS probes will be presented in comparison to spatially discrete measurements obtained using the conventional probes. Also presented will be a review of the installation procedures used and integration of the new sensors into the TRACE sensor network.