DOI: 10.5281/zenodo.10080897
title: NOAA PSL Soil Moisture and Surface Temperature Probe Data for SPLASH

description: This dataset contains measurements from a hand-held FieldScout TDR Soil Moisture Meter within the 0-10 cm soil depth of: Time (UTC), GPS locations, Electrical Conductivity (EC), compensated percent volumetric water content (VWC), soil surface temperature (T), and rod length (inches) obtained during the Study of Precipitation, the Lower Atmosphere, and Surface for Hydrology (SPLASH) campaign sponsored by the National Oceanic and Atmospheric Administration (NOAA).  These data were collected around the SPLASH campaign areas near Avery Picnic (38.972425 degrees N,106.996855 degrees W) and Kettle Ponds (38.942005 degrees N,106.973006 degrees W) in the East River Watershed in Colorado from between June 1st, 2022 and September 18th, 2023, under support from the NOAA Physical Sciences Laboratory and NOAA Weather Program Office under award NA21OAR4590363.
Two file formats are provided: one version is text csv format and the second version is in NetCDF.
Volumetric water content calculations: 
Data were calibrated and adjusted, with a soil-specific sample set, to improve accuracy and compensate for the meter's default "standard" soil type used in the sampling.  VWC data was correlated by measuring the weight of a known volume of soil from a range of saturation values. Samples were measured and weighed, dried at 105 degrees C for 48 hours, then weighed again. Calculations of VWC (VWC = 100*(Mwet - Mdry)/(w*Vtot) )were plotted against TDR readings.  Where: 
Mwet, Mdry = mass (g) of wet and dry soil respectively 
Vtot = total soil volume (ml) 
w = density of water (1g/ml) 
A regression analysis  to correlate TDR readings to the samples is below and was applied to the dataset.
vwc_calculated = vwc_probe * slope + intercept
slope = 1.20665, intercept = 0.0837017 m3/m3, slope_std_error = 0.09229, intercept_std_error = 0.0217403 m3/m3
Definitions:
TDR (Time Domain Reflectometry): A technique for measuring soil moisture content that uses the fact that water has a much higher dielectric permittivity than air, soil minerals, and organic matter. 
VWC (Volumetric Water Content): The ratio of the volume of water in a given volume of soil to the total soil volume expressed as a decimal or a percentage. The percent of the soil volume that is filled with water. At saturation, the VWC will equal the soil porosity (Saturation is typically around 50%).
EC (Electrical Conductivity): A measure of how well the soil solution conducts electricity. The EC is influenced by the amount of salt and water in the soil. 
The VWC measured by TDR is an average over the length of the waveguide. 
Soil Characteristics:
Soil at both Kettle Ponds (KEP1 and KPA) locations and Avery Picnic (AYP) were lab tested for composition as follows:
Sample ID       Depth(in.)       Sand(%)     Silt(%)     Clay(%)     Soil Texture
------------------------------------------------------------------------------------------------------  
KEP1               2                      43                35            22              Loam
AYP                 2                      40                35            25              Loam
KPA                 2                      35                42            22              Loam
------------------------------------------------------------------------------------------------------