Volumetric soil moisture

In addition to the data provided by the permanent in situ networks (BPN) installed over BERMS research sites, the volumetric soil moisture content will be measured from the BERMS temporary in situ network (BTN), and the ground team sampling (GTS). These 3 resources will be used for the validation of SMOS products, the development of microwave algorithms, the transferability and compatibility of BPN and BTN data, and the study of the scaling characteristics of BPN for long-term validation of soil moisture products including SMOS and SMAP.

BERMS Permanent Network (BPN): It consists of 6 stations installed several years ago over BERMS research sites (OBS, OJP, FEN, H75, H94 and H02). Volumetric soil moisture data is measured at different depth.

BERMS Temporary Network (BTN): It is composed of about 20 Stevens Hydra Probes distributed over an area of ~ 40 km diameter (SMOS footprint) that encompasses the BPN sites. The network will provide 5-cm depth soil moisture from June to August. Some BTN stations will be co-located at the BPN for validation/verification purposes.

Ground team sampling (GTS): It will be a 1-day (anticipated to be June 16th, 2010) sampling conducted simultaneously to aircrafts and SMOS acquisitions. Soil moisture will be collected with Hydra probes over about 30–35 locations spatially well distributed over BERMS study area in consideration of the BTN and road accessibility.
The sampling strategy shown below was developed to satisfy the spatial distribution of soil moisture measurements for the validation of soil moisture retrievals from SMOS and aircraft acquisitions. Since the GTS locations are all along accessible roads and trails, the sampling will be conducted at 3 measurement points located within the surronding canopy at a nominal distance of 20, 25 and 30 m from the indicated GTS site. For each of the three measurement points at a GTS site, 3 Hydra probe readings will be collected.

Diagram of the GTS sampling strategy