
Forest Soil Moisture Monitoring Network (FSMMN)


** OVERVIEW **

 This data package contains quality-controlled, multi-depth soil moisture and
 temperature observations from the Hubbard Brook Experimental Forest, NH,  
 collected as part of the Forest Soil Moisture Monitoring Network (FSMMN). The
 FSMMN is a coordinated monitoring effort across three U.S. Forest Services
 experimental forests, including at Hubbard Brook (NH), Fernow (WV), and Coweeta 
 (NC) to monitor and generate long-term soil moisture datasets across multiple 
 forested watersheds in the U.S.

 Sensors measure volumetric water content (VWC), soil matric potential (SMP),
 soil temperature, and soil electrical conductivity (EC) at three depth intervals
 (shallow: 10-20 cm, mid: 50 cm, deep: 60-100 cm) at multiple sites distributed
 across catchments within each forest. Observations are recorded hourly and
 undergo automated and manual quality control (QC). Data are
 updated annually.

 Data files for the other FSMMN forests are available in separate EDI packages:

    Hubbard Brook Experimental Forest (NH):
    https://doi.org/10.6073/pasta/2eb8ea3a25e81ead1188af94ccfede72

    Fernow Experimental Forest (WV):
    https://doi.org/10.6073/pasta/3394903db59772e9aef31c7b9628fb42

    Coweeta Hydrologic Laboratory (NC):
    https://doi.org/10.6073/pasta/3e11ea6cf7bcfe8791a3abd29c9b7638

 For full network description, site characteristics, instrumentation details, and
 QC procedures, see the associated manuscript:

    Pennino, A., Piche, E., Rau, B., Rooney, E., Oishi, A.C., Green, M.,
    Wills, S., and Connolly, S. (in review). The Forest Soil Moisture Monitoring
    Network (FSMMN): Multi-depth soil moisture, matric potential, and temperature
    data from three U.S. experimental forests. Earth System Science Data. [DOI]



** PACKAGE CONTENTS **

 This package contains the following files:

   [siteID].csv          Hourly time series of soil moisture and temperature for
                         one monitoring site (one file per site). Each site
                         represents one instrumented soil profile.

   sensor_metadata.csv   Sensor installation metadata linking each sensor to its
                         site, depth, logger, and deployment period

   pedon_data.csv        Soil profile descriptions collected at each site during
                         sensor installation

   flag_codes.txt        Explanation of the codes used during the QC procedure to
                         denote suspicious or erroneous data.



** FILE DESCRIPTIONS **


 1. TIMESERIES DATA FILES ([siteID].csv)

 One CSV file per monitoring site. The filename encodes the site identifier
 (siteID). Each file contains hourly observations for the full deployment period
 at that site.

 Column Explanation and Naming Convention: 

 {measurement}_{depth}:

      {measurement}

      vwc                Volumetric water content (m3/m3)
      matric_kPa         Soil matric potential (kPa)
      matric_tempC       Temperature recorded by matric potential sensor (deg C)
      vwc_temp_C         Temperature recorded by VWC sensor (deg C)
      satext_mScm        Soil electrical conductivity, TEROS 12 only (mS/cm)

      {depth}
    
      Contextualizes the sensor within the pedon horizon at that site. Depth labels 
      correspond to the horizon designations recorded in pedon_data.csv and reflect 
      actual installation depth rather than a fixed numeric depth. See 
      sensor_metadata.csv for the exact depth in centimeters for each sensor. If 
      an “a” or “b” is attached, then this was a duplicate measurement, (e.g., two 
      sensors at the same depth).

  Each measurement column has three associated QC columns:

      {measurement}_{depth}_raw         Direct value recorded
      {measurement}_{depth}_qc          Quality-controlled value
      {measurement}_{depth}_flag        Flag code(s) assigned during QC (see QC Flag
                                        Codes section)

 Logger diagnostic columns

      logger_battPerc        Logger battery percentage (%)
      logger_battVolt        Logger battery voltage (V)
      logger_refPress        Logger reference pressure (kPa)
      logger_tempC           Logger internal temperature (deg C)


 2. SENSOR METADATA (sensor_metadata.csv)

 One row per sensor deployment. Links each sensor to its site, logger, depth,
 and deployment period. Use this file to identify which sensors correspond to
 which data columns in the time series files.

      siteID              Matches filename of timeseries file
      watershed           Watershed identifier within the forest
      lat                 Site latitude (decimal degrees)
      lon                 Site longitude (decimal degrees)
      port                Logger port number the sensor is connected to
      serial              Sensor serial number
      model               Sensor model (TEROS 11, TEROS 12, or TEROS 21)
      depth_cm            Sensor installation depth (cm)
      duplicate_depth     If a replicate VWC sensor was installed at the same 
                          depth, denoted by “a” or “b”
      log_start           Date logging began for this sensor
      log_end             Date logging ended (NA if ongoing)
      status              Current sensor status (active, inactive, removed)
      notes               Any notes on sensor installation or known issues


 3. SOIL PROFILE DESCRIPTION DATA (pedon_data.csv)

 One row per soil horizon described at each site during sensor installation.
 Provides the soil profile context for interpreting sensor placement and the
 {depth} label used in time series column names.

      siteID              Unique site identifier; links to time series files and
                          sensor_metadata.csv
      watershed           Watershed identifier within the forest
      logger              Logger identifier associated with this site
      field_horizon       Horizon designation (e.g., A, Bhs, BC, C)
      top                 Top depth of horizon (cm)
      bottom              Bottom depth of horizon (cm)
      continues           Indicates if a horizon continues below described depth
      hue                 Munsell color hue
      value               Munsell color value
      chroma              Munsell color chroma
      texture_class       USDA texture class (e.g., sandy loam, loam) as textured
                          in the field
      structure           Soil structure description
      note                Additional field observations


 4. QC FLAG CODES (flag_codes.txt)

 Each measurement column in the time series files has an associated {_flag}
 column. Flag codes indicate the type of quality concern identified for each 
 observation. Multiple flags may be assigned to a single observation and are 
 recorded as a string of flag characters.

 NOTE: Flagged values are retained in the {_raw} columns. The {_qc} columns 
 contain the cleaned values, with flagged observations replaced by NA where 
 removal was warranted. Users should review flag codes and make their own 
 determination about whether to include or exclude flagged observations based on 
 their application.

  Flag  Name                      Removed    Description
  ----  ------------------------  --------   ------------------------------------
  t     Time series insert        No         New rows were introduced where hourly 
                                             observations were missing from the 
                                             1-hour interval data. Missing values 
                                             across columns were populated with NA 
                                             values.

  n     Missing value             No         Pre-existing NA entries in the raw
                                             dataset, flagged to distinguish from
                                             time series insertions.

  c     Installation buffer       Yes        First seven days of matric potential
                                             sensor data collected was cleared to 
                                             allow full equilibration with 
                                             surrounding soil.

  f     Below freezing            Yes        Values recorded when sensor
                                             temperature was at or below 0 degrees
                                             C, removed until temperature returned
                                             above 0.25 degrees C.

  s     Record skipping           No         Values logged intermittently under
                                             adequate battery conditions (>5%),
                                             flagged to identify potential sensor
                                             issues.

  r     Sensor range              No         Values outside the manufacturer's
                                             reported accuracy range for the
                                             sensor.

  z     Zero EC                   Yes        TEROS 12 reports 0 when EC is below
                                             detection limit. Zero EC values
                                             replaced with NA.

  l     Limited data              No         Fewer than 7 days of observations
                                             within a 30-day window.

  p     Precipitation step        No         Abrupt increase in VWC (>3 SD from
                                             mean step change) with no
                                             precipitation in the preceding 12
                                             hours. 

  .     Precip step (incomplete)  No         Same as p but local precipitation
                                             data was unavailable to complete
                                             the validation check.

  X     Sensor malfunction        Yes        Sensor identified as malfunctioning.
                                             All values, or all values after a
                                             specified date, removed.



** LINKING FILES **

 The three file types in this package are linked through shared identifiers:

      siteID                   Links time series data files to rows in
                               sensor_metadata.csv and pedon_data.csv

      logger                   Links sensor_metadata.csv to pedon_data.csv

      {depth} in columns       Informs where each sensor was installed within the 
                               soil horizons described in pedon_data.csv and the 
                               specific sensor installed in sensor_metadata.csv

 A diagram illustrating the relationships among files in this package is provided
 in the associated manuscript (Figure A4).



** SENSOR SPECIFICATIONS **

 Three sensor models were used across the FSMMN. Specifications below follow
 manufacturer documentation (METER Group, Inc., Pullman, WA).


 TEROS 11 (VWC, temp)
     VWC range: 0.00-0.7 m3/m3
     VWC resolution: 0.0010 
     VWC accuracy: +/-0.03  
     Temperature range: -40 to 60 C
     Temperature resolution: 0.1
     Temperature accuracy: +/-1 < 0 C; +/- 0.5 > 0 C

 TEROS 12 (VWC, temp, EC)
     VWC range: 0.00-0.7 m3/m3
     VWC resolution: 0.0010 
     VWC accuracy: +/-0.03  
     Temperature range: -40 to 60 C
     Temperature resolution: 0.10
     Temperature accuracy: +/-1 < 0 C; +/- 0.5 > 0 C
     EC range: 00-20,000 uS/cm
     EC resolution: 1 uS/cm

  TEROS 21 (SMP, temp)
     SMP range: 0 to -100,000 kPa
     SMP resolution: 0.1 
     SMP accuracy: +/- 10% from 100 to -5 kPa


All sensors were connected to a ZL6 datalogger (METER Group, Inc.). VWC values
are calculated from apparent dielectric permittivity using factory calibration
equations. Site-specific calibration was not performed.



** CONTACT AND CITATION **

 Data contacts: Emily Piche (epiche@esf.edu) and Amanda Pennino (apennino@esf.edu)

 Suggested citations

    Dataset:

    NRCS-USFS Forest Soil Moisture Monitoring Network. 2025. NRCS-USFS Soil 
    Moisture Measurements - Hubbard Brook Experimental Forest, 2023-2025 ver 1. 
    Environmental Data Initiative. 
    https://doi.org/10.6073/pasta/2eb8ea3a25e81ead1188af94ccfede72 

    Associated manuscript:

    Pennino, A., Piche, E., Rau, B., Rooney, E., Oishi, A.C., Green, M.,
    Wills, S., and Connolly, S. (in review). The Forest Soil Moisture Monitoring
    Network (FSMMN): Multi-depth soil moisture, matric potential, and temperature
    data from three U.S. experimental forests. Earth System Science Data. [DOI]

 

 Last updated: May 2026
