Flux results

Computed results are in the summary file. It is accompanied by metadata, which includes parameters related to the flux computations.

Summary file variables

In Table 7‑1 you will find the variables included in a summary file. Under the Label column, variables listed with Fgas will vary based upon the gas species measured by the analyzer. Under the Device column, variables listed with FLUX_source vary based upon the device (instrument) used. For example a flux of CO2 calculated using an LI-870 CO2/H2O Analyzer would appear as: FLUX_LI-870, FCO2_DRY, [μmol mol-1].

Table 7‑1. Summary file variables.
Label Units Device Description
Fgas nmol m-2s-1,
μmol m-2s-1, or
mmol m-2s-1		 FLUX_source Flux of the gas species based on exponential fit
Fgas_dCdt nmol mol-1s-1,
μmol mol-1s-1, or
mmol mol-1s-1		 FLUX_source Slope used to compute flux
Fgas_CV   FLUX_source CV for flux calculation
Fgas_R2   FLUX_source Regression coefficient of fit to accumulation curve
Fgas_SEI   FLUX_source Standard error for the intercept
Fgas_SES   FLUX_source Standard error for the slope
Fgas_A   FLUX_source Curvature parameter of exponential fit
Fgas_Cx nmol mol-1,
μmol mol-1, or
mmol mol-1		 FLUX_source Asymptotic gas concentration
Fgas_C0 nmol mol-1,
μmol mol-1, or
mmol mol-1		 FLUX_source Gas concentration at time zero
Fgas_T0 s FLUX_source Time zero for fitting accumulation curve
Fgas_ITER   FLUX_source Number of iterations required to fit the exponential model
Fgas_N   FLUX_source Number of data points used in the flux calculation
DATE YYYY-MM-DD LI-8250 Date at the start of the observation
TIME HH:MM:SS LI-8250 Time at the stat of the observation
DOY   LI-8250 Decimal day of the year at the start of the measurement
PORT   LI-8250 or
8250-01		 Port being sampled
H   CHAMBER Horizontal value from HVR
V   CHAMBER Vertical value from HVR
LATITUDE ° CHAMBER Chamber or multiplexer latitude
LONGITUDE ° CHAMBER Chamber or multiplexer longitude
TA C CHAMBER Air temperature used in flux calculation
PA kPa LI-8250 Pressure used in flux calculation
CO2_DRY μmol mol-1 LI-870 or
LI-78xx		 Carbon dioxide dry mixing ratio
CH4_DRY nmol mol-1 LI-7810 Methane dry mixing ratio
H2O mmol mol-1 LI-870 or
LI-78xx		 Water vapor mole fraction
N2O_DRY nmol mol-1 LI-7820 Nitrous oxide dry mixing ratio
Ancillary SDI-12 or light sensor data   CHAMBER Data from connected sensors

Flux metadata

Flux metadata includes parameters related to the flux computations.

Table 7‑2. Flux metadata definitions. The DEVICE for these variables is FLUX.
Interface variable Units Data file variable Description
Deadband s DEADBAND Deadband length
Stop Time s STOP_TIME Length of data used for the flux computation
Dilution Source   DILUTION_SOURCE Name of the device that provided the water vapor measurement used for dilution correction (NONE for a dry gas)
Dilution Units   DILUTION_UNIT Units of water vapor measurement (NONE for a dry gas)
Temperature   TEMPERATURE Label of the temperature measurement used in flux calculation
Temperature Source   T_SOURCE Device of temperature measurement used in flux calculation
Gas   GAS Name of the gas species the flux was computed for
Gas Source   GAS_SOURCE Name of the device that measured the gas for which the flux was computed
Replicate   REPLICATE Numerical value of R from the chamber's HVR field