European Fluxes Database Cluster

Variables codes

Rules for variables names

In this page all the information needed to correctly report variables to the database are provided. To submit the data it is fundamental to use the correct variables names and units as reported in the table at the bottom of the page. However, in addition ot the variable name it is requested to use a 3 figures code which identifies univocally the location within the site where measurements are taken. The importance of this code is related to the possibility to associate to each variable a set of metadata like the method or instrument used, the measurement depth/height, the last calibration of the sensor etc.

Generally, the name of the variable has to be indicated as:


VAR= variable name (refer to the list of input variables)

The first figure stands for the position of the sensors on a 2D space. For instance, if soil temperature is measured at 3 different locations, these can be numbered as 1, 2, 3.







location 1


location 2


location 3


The second figure represents the vertical level (height above the ground/depth of the soil) of the sensors. Supposing to measure soil temperature at 3 different depths along a vertical profile at each location, then each variable can be identified as follows:








depth 1







depth 2







depth 3

location 1


location 2


location 3



Numeration increases moving downwards along a vertical profile but same number at two different locations can indicate different height/depth, that is specified in the metadata. So for example the deeper soil temperature measurement point in two different profiles of 4 sensors each will be indicated as TS_1_4_1 and TS_2_4_1 even if the first is at 80cm and the second 120cm below ground.

The third figure identifies the presence of replicated measurements in the same location. For instance, given 2 replicates of soil temperature measurements at position 1 and depth 1 (i.e. for sensors comparison), these would be indicated as:


TS_1_1_1   TS_1_1_2


Another example where the third figure should be used is for measurements at tree level like sap flow sensors. In this case the first figure indicate the tree (again specified in the metadata), the second the measurement height if you have for example sap flow measurements on the same tree at different heights and the third can be used to identify different sensors at the same height, commonly used in sap flow measurements.

Remember: All variables to be submitted must be characterized by the 3 figure code and in case of a variable being measured with a single sensor in a given point in space, the three figures of the code clearly equals 1.

New variables

We tried to consider all the common variables collected in the network also on the basis of what has been collected in previous projects. However new measurements are continuously added and it is possible that a variable to be submitted is not present in the “Variables codes”. In this case please contact the Databse Staff at the address and we will think together to the best solution. In any case do not send variables with names not consistent with those listed because these would be rejected by the system.

IMPORTANT: Additional information regarding the variables (height, depth) must be included in the metadata and not in the data file neither in the variable name. All additional information included in the data file are lost during the upload process.

Variables Codes List

Drag a column header and drop it here to group by that column
APARAbsorbed PAR (400-700 nm)umolPhoton m-2 s-1Database
CH4Methane concentrationppb (nmolCH4 mol-1)Database
CO2CO2 concentrationppm (umolCO2 mol-1)Database
CO2C13Stable isotopic composition of CO2 - C13 (i.e., d13C of CO2)Database
D_SNOWSnow depthcmDatabase
DBHDiameter at breast height (1.3m) from dendrometercmDatabase
EVIEnhanced Vegetation IndexnondimensionalDatabase
EVIEnhanced Vegetation IndexnondimensionalDatabase
FCCO2 fluxumolCO2 m-2 s-1Database
FC_CMBNEE measured using transparent chambersumolCO2 m-2 s-1BADM or Database
FC_SSITC_TESTQuality check - CO2 flux - * see the notenondimensionalDatabase
FCH4Methane (CH4) fluxnmolCH4 m-2 s-1Database
FCH4_CMBMethane flux measured using chambersnmolCH4 m-2 s-1BADM or Database
FCH4_PIMethane (CH4) flux (PI processed version)nmolCH4 m-2 s-1Database
FETCH_70Fetch at which footprint cumulated probability is 70%mDatabase
FETCH_80Fetch at which footprint cumulated probability is 70%mDatabase
FETCH_90Fetch at which footprint cumulated probability is 90%mDatabase
FETCH_FILTERFootprint quality check: 0 if Fetch70 is outside the fetch or however to be discarded due to footprint issues, 1 if the data are oknondimensionalDatabase
FETCH_MAXFetch at which footprint cumulated probability is maximummDatabase
FH2OWater vapor (H2O) turbulent flux (no storage correction)mmolH2O m-2 s-1Database
FN2ONitrous oxide (N2O) fluxnmolN2O m-2 s-1Database
FN2O_CMBN2O flux measured using chambersnmolN2O m-2 s-1BADM or Database
FNONO fluxnmolNO m-2 s-1Database
FNO_CMBNO flux measured using chambersnmolNO m-2 s-1BADM or Database
FNO2NO2 fluxnmolNO2 m-2 s-1Database
FNO2_CMBNO2 flux measured using chambersnmolNO2 m-2 s-1BADM or Database
FO3O3 fluxnmolO3 m-2 s-1Database
FO3_SSITC_TESTQuality check - Ozone flux * see the notenondimensionalDatabase
GSoil heat fluxW m-2Database
GPP_PIGross Primary Production (submitted by PI)umolCO2 m-2 s-1Database
HSensible heat fluxW m-2Database
H_PISensible Heat (PI processed version)umolCO2 m-2 s-1Database
H_SSITC_TESTQuality check - sensible heat flux - * see the notenondimensionalDatabase
H2OWater (H2O) vapor mole fractionppt (mmolH2O mol-1)Database
LELatent heat fluxW m-2Database
LE_PILatent heat (PI processed version)W m-2Database
LE_SSITC_TESTQuality check - latent heat flux - * see the notenondimensionalDatabase
LEAF_WETLeaf wetness%Database
LW_INIncoming Longwave radiation (in the range from 4 to 50 micron)W m-2Database
LW_OUTOutgoing Longwave radiation (in the range from 4 to 50 micron)W m-2Database
MCRICarotenoid Reflectance Index (Gitelson et al., 2002)nondimensionalDatabase
MO_LENGTHMonin-Obukhov lengthmDatabase
MTCIMeris Terrestrial Chlorophyll Index (Dash and Curran, 2004)nondimensionalDatabase
N2ONitrous oxide (N2O) mole fractionnmolN2O mol-1BADM or Database
NDVINormalized Difference Vegetation IndexnondimensionalDatabase
NEE_PINet Ecosystem Exchange (PI processed version)umolCO2 m-2 s-1Database
NETRADNet radiation (including SW and LW components)W m-2Database
NIRVNear Infrared Vegetation Index (Badgley et al., 2017)W m-2 sr-1 nm-1Database
NONO concentrationppb (nmolNO mol-1)Database
NO2NO2 concentrationppb (nmolNO2 mol-1)Database
O3O3 concentrationppb (nmolO3 mol-1)Database
P_SNOWSnowfall – snow precipitationmm (or water)Database
PAAtmospheric pressurekPaDatabase
PBLHPlanetary boundary layer heightmDatabase
PPFD_BC_INBelow canopy PPFD (400-700 nm)umolPhoton m-2 s-1Database
PPFD_DIFDiffuse PPFD (400-700 nm)umolPhoton m-2 s-1Database
PPFD_DIRPhotosynthetic photon flux density, direct incomingµmolPhoton m-2 s-1Database
PPFD_INPhotosynthetic Photon Flux Density (400-700 nm)umolPhoton m-2 s-1Database
PPFD_OUTReflected PPFD (400-700 nm)umolPhoton m-2 s-1Database
PRIPhotochemical reflectance indexnondimensionalDatabase
R_UVAUVA radiationW m-2Database
R_UVBUVB radiationW m-2Database
RECO_PIEcosystem Respiration (submitted by PI)umolCO2 m-2 s-1Database
REDClRed Edge Chlorophyll IndexnondimensionalDatabase
REPRed Edge Position (Dash and Curran, 2004)nmDatabase
RHRelative humidity%Database
SAP_DTDifference of probes temperature for sapflow measurements°CDatabase
SAP_FLOWSapflowmmolH2O m-2 s-1Database
SBHeat storage in biomassW m-2Database
SCCO2 storage in air below flux measurement levelumolCO2 m-2 s-1Database
SCH4Methane (CH4) storage fluxnmolCH4 m-2 s-1Database
SGHeat storage in the soil above the soil heat fluxes measurementW m-2Database
SHHeat storage in air below flux measurement levelW m-2Database
SLELatent heat storage below flux measurement levelW m-2Database
SPEC_NIR_INIncoming radiation (infra-red band)W m-2 nm-1Database
SPEC_NIR_OUTOutgoing radiation (infra-red band)W m-2 sr-1 nm-1Database
SPEC_PRI_REF_INIncoming radiation at 568 nm W m-2 nm-1Database
SPEC_PRI_REF_OUTOutgoing radiation at 568 nm W m-2 sr-1 nm-1Database
SPEC_PRI_TGT_INIncoming radiation at 529 nm W m-2 nm-1Database
SPEC_PRI_TGT_OUTOutgoing radiation at 529 nm W m-2 sr-1 nm-1Database
SPEC_RED_INIncoming radiation (red band)W m-2 nm-1Database
SPEC_RED_OUTOutgoing radiation (red band)W m-2 sr-1 nm-1Database
SRSimple RationondimensionalDatabase
STEMFLOWStem flowmmDatabase
SW_BC_INBelow canopy incoming short wave radiation W m-2Database
SW_DIFDiffuse incoming Shortwave radiation (in the range from 0.3 to 4.5 micron)W m-2Database
SW_INIncoming Shortwave radiation (in the range from 0.3 to 4.5 micron)W m-2Database
SW_OUTOutgoing Shortwave radiation (in the range from 0.3 to 4.5 micron)W m-2Database
SWCSoil water content%Database
T_BOLEBole temperature°CDatabase
T_CANOPYCanopy temperature°CDatabase
T_DPDew Point Temperature°CDatabase
T_SONICSonic Temperature°CDatabase
T_SONIC_SIGMAStandard deviation of the sonic temperature°CDatabase
TAAir temperature°CDatabase
TAUMomentum fluxkg m-1 s-2Database
TAU_SSITC_TESTQuality check - momentum flux - * see the notenondimensionalDatabase
TCARITransformed Chlorophyll Absorption in Reflectance IndexnondimensionalDatabase
TSSoil temperature°CDatabase
U_SIGMAStandard deviation of velocity fluctuations (towards main-wind direction after coordinates rotation)m s-1Database
USTARFriction velocitym s-1Database
V_SIGMAStandard deviation of lateral velocity fluctuations (cross main-wind direction after coordinates rotation)m s-1Database
VPD_PIVapour pressure deficit (PI processed version)hPaDatabase
W_SIGMAStandard deviation of vertical velocity fluctuations m s-1Database
WDWind directionDecimal degreesDatabase
WD_SIGMAStandard deviation of wind direction (Yamartino, 1984)decimal degreeDatabase
WSWind speedm s-1Database
WS_MAXMaximum wind speed m s-1Database
WTDWater table depthmDatabase
ZLStability parameternondimensionalDatabase

* note: for the quality flag definition please refer to this document: Quality Flags Definition