Soil variables and constants

Variables related to soil gas flux have their own groups in the data dictionary and data files.

The SoilConst group

Constants are computational constants used in the flux calculation. These can be found in the Data Dictionary under the group called SoilConst.

**Table 11‑1**. Soil gas flux computational constants.
Constant	Description
Vcham	The volume of the chamber.
Virga	Volume of the IRGA.
Area	Exposed soil area within a collar.
Offset	Height of the chamber base above the soil surface.
Vtotal	Total volume.
Ctarget	Target concentration for computing fluxes.

These settings can be found in the Data Dictionary under the group called SoilConfig.

**Table 11‑2**. Soil measurement settings.
Meas	Description
Rep duration	Time (s) chamber is closed for each repetition.
Dead band	Delay (s) after closing to begin computations.
# Reps	Number of repetitions per measurement.
Extra	Delay (s) after opening before starting next repetition.
ID Tag	Identifier, used in the file name.
Soil Type	Needed for the Stevens Probe.
Tsoil	The source of a soil temperature (Stevens probe, Tleaf, Tleaf2, or none).

Real-time data during a measurement is available in the group called SoilData. Some of these are shown in the Measure Flux window.

**Table 11‑3**. Soil data from the group called **SoilData**.
Label	Description
TIME	The time_t value of the data record.
CStatus	Status of chamber ("Open", "Closing", "Closed", "Opening").
MStatus	Status of the measurement ("Idle", "Closing", "Dead band", "Sampling", "Opening", "Waiting").
MStatusN	Numeric status of the measurement (0 = "Idle", 1 = "Closing", 2 = "Dead band", 3 = "Sampling", 4 = "Opening",
Rep	Current repetition and total. e.g., 3/4.
Elapsed	During measurement, elapsed time since chamber closed.
Progress	Percent of the measurement completed.
RepProg	Percent of the current rep that is completed.
CO2	Value comes from CO2_s in group Meas.
H2O	Value comes from H2O_s in group Meas.
Cdry	Dry CO₂. Value comes from CO2_s_d in group Meas2.
Tsoil	Soil temp. Source depends on setting of Tsoil in SoilConfig.
Msoil	Soil moisture, (measured by Stevens Probe).
Tair_sc	Air temperature within the soil chamber.
Pressure	Value comes from Pa in group Meas.
RH	Computed RH in the soil chamber.
dCdry/dt	Rate of change of Cdry over previous 2 seconds
F-to	An estimate of what the final flux will be at time `t_o`

When a rep is finished, a SoilComp2 record is published.

**Table 11‑4**. SoilComp2 record published at the end of a repetition.
Label	Description
MeasNum	Measurement number.
RepNum	Repetition number.
F_target	Flux computed Cdry = C_target.
F_to	Flux computed at Cdry = C_o.
Cdry_to	Cdry concentration at chamber close.
P_to	Pressure at chamber close.
T_to	Chamber air temp at chamber close.
W_to	Chamber water mole fraction at chamber close.
slope	Slope of dCdry/dt as function of Cdry.
intercept	Intercept of dCdry/dt as function of Cdry.
Ts_avg	Average soil temperature over the rep
Ms_avg	Average soil moisture over the rep