A soil moisture dataset over the Brazilian semiarid region
This dataset contains soil moisture measured over the Brazilian Semiarid region from August 2015 to April 2019. An observational network of automatic ground stations was established by the National Center for Monitoring and Early Warning of Natural Disasters (CEMADEN) with the aim of supporting monitoring activities over the driest and most drought-affected region in the country. The sites are mostly characterised by family farming and rainfed agriculture. Soil volumetric water content is obtained by measuring the dielectric constant of the soil at 70 MHz frequency, which minimizes salinity and textural effects (model EC-5, Decagon Devices, Pullman, WA, USA). Probes use the default calibration, resulting in a precision of approximately ±0.03 m3 m-3. Measurements were made hourly at 0.1 m and 0.2 m depths; a subset of stations (10% of the original network, evenly distributed) had measurements at 0.1 m, 0.2 m, 0.3 m, and 0.4 m depths. Rainfall measurements are also included in this version of the dataset. Measurements were accumulated hourly. A total of 360 stations were selected after a quality control process. Data availability is approximately 2 years long on average, reaching up to 4 years in some stations. Gaps caused by instrument malfunction or data transmission problems are occasional on the data. Validation and consistency were assessed by comparing trends in soil vertical neighbour data and rainfall records collected by each station. Stations with at least two months of soil moisture data were kept on the database. Each file available here contains the time series and the metadata with information on the city, the Brazilian state, the geographic coordinates, and the soil texture (fraction of sand, silt and clay). Soil information was derived from 1 kg disturbed samples collected at each site. Data for individual stations are in the compressed file PCDs_.zip while a list summarising stations information is found in the file _Stations.xlsx. First applications of this dataset and further details on methodology and site can be found in Zeri et al. (2018, https://doi.org/10.3390/w10101421). Version 2 of the dataset includes rainfall measurements, 3 new stations, and the inclusion of records incorrectly removed during the quality control of version 1.