Variables
The main variables of FP2026.1: column name, unit and meaning. All are half-hourly. The index TIMESTAMP_MIDDLE marks the middle of each half-hour, in UTC+01:00 all year (no daylight saving). The _INFO.md file that comes with the dataset lists all 548 columns with unit and description; this page covers the columns most users need.
Fluxes
The fluxes come from the enclosed-path LI-7200 (IRGA72). The column names follow the processing levels of the post-processing chain. For example, NEE_L3.1_L3.3_CUT_50_QCF_gfXG is NEE after Level 3.1 (storage term) and Level 3.3 (USTAR filter, scenario CUT_50), from records with quality flag 0 or 1 (QCF), gap-filled with XGBoost (gfXG).
| Column | Unit | Meaning | Page |
|---|---|---|---|
NEE_L3.1_L3.3_CUT_<nn>_QCF_gfXG |
µmol m-2 s-1 | Net ecosystem exchange of CO2: FC plus the storage term. Negative values are uptake by the ecosystem. One column per USTAR scenario, <nn> = 16, 50, 84. |
L4.1 |
NEE_L3.1_L3.3_CUT_50_QCF_gfXG_RANDUNC |
µmol m-2 s-1 | Random uncertainty of NEE, 1 sigma (Pastorello et al. 2020). |
L4.1 |
NEE_L3.1_L3.3_CUT_50_QCF_gfXG_USTARUNC |
µmol m-2 s-1 | USTAR uncertainty: half the difference between the CUT_84 and CUT_16 series. |
L4.1 |
NEE_L3.1_L3.3_CUT_50_QCF_gfXG_JOINTUNC |
µmol m-2 s-1 | Random and USTAR uncertainty combined. | L4.1 |
LE_L3.1_L3.3_CUT_NONE_QCF_gfXG |
W m-2 | Latent heat flux. No storage term, no USTAR filter. | L4.1 |
ET_L3.1_L3.3_CUT_NONE_QCF_gfXG |
mm (30 min)-1 | Evapotranspiration, computed from the gap-filled LE. |
L4.1 |
H_L3.1_L3.3_CUT_NONE_QCF_gfXG |
W m-2 | Sensible heat flux from the sonic anemometer. No storage term, no USTAR filter. | L4.1 |
FLAG_<column>_ISFILLED |
- | 0 where the value was measured, otherwise filled. | L4.1 |
Each gap-filled column also exists with _gfMDS instead of _gfXG, filled with MDS. These are for comparison only; use the XGBoost columns. The three USTAR thresholds are 0.272, 0.304 and 0.340 m s-1 (Level 3.3).
| Column | Unit | Meaning | Page |
|---|---|---|---|
NEE_L3.1_L3.3_CUT_<nn>_QCF |
µmol m-2 s-1 | Measured NEE after all quality tests and the USTAR filter, not gap-filled. _QCF0 instead of _QCF keeps the records with quality flag 0 only. |
L3.3 |
LE_L3.1_L3.3_CUT_NONE_QCF, H_L3.1_L3.3_CUT_NONE_QCF |
W m-2 | Measured LE and H after all quality tests, not gap-filled (also with _QCF0). |
L3.2 |
FC |
µmol m-2 s-1 | CO2 flux from EddyPro (Level 1), without storage term and without quality filtering. | L1 |
SC_SINGLE_gfRMED_L3.1 |
µmol m-2 s-1 | CO2 storage term from the concentration at the measurement height, gap-filled with a rolling median, as added to FC to give NEE. |
L3.1 |
LE, H |
W m-2 | Latent and sensible heat flux from EddyPro (Level 1), without quality filtering. | L1 |
USTAR |
m s-1 | Friction velocity. | L3.3 |
FLAG_L2_<flux>_QCF, FLAG_L3.1_<flux>_QCF, … |
- | Overall quality flag after each level: 0 best, 1 good, 2 rejected. | L2 |
SW_IN_POT, DAYTIME, NIGHTTIME |
W m-2, -, - | Potential incoming shortwave radiation for the middle of the half-hour, and the day and night flags derived from it (1 where the condition holds). | - |
The other Level-1 columns are the EddyPro output: the fluxes after each correction stage, the quality tests, wind and turbulence statistics, footprint distances and raw-data statistics.
The gap-filled ET_..._gfXG and ET_..._gfMDS are in mm per half-hour. The Level-1 column ET from EddyPro is in mm h-1.
Meteorological variables
Measured at the tower at 47 m (T1_47_1) or in the soil profile at the forest floor (FF1_<depth>, depth in metres). Each variable has its own page with its columns, flags, coverage and known limitations. The provenance flags (FLAG_<column>_ISFILLED, _SOURCE and others) are defined there.
| Variable | Columns | Unit | Page |
|---|---|---|---|
| Incoming shortwave radiation | SW_IN_T1_47_1_gfXG |
W m-2 | SW_IN |
| Air temperature | TA_T1_47_1_gfXG, TA_T1_47_1_HOMOGENIZED_gfXG |
°C | TA |
| Photosynthetic photon flux density | PPFD_IN_T1_47_1_gfXG |
µmol m-2 s-1 | PPFD_IN |
| Relative humidity | RH_T1_47_1, RH_T1_47_1_HOMOGENIZED |
% | RH |
| Air pressure | PA_T1_47_1 |
kPa | PA |
| Incoming longwave radiation | LW_IN_T1_47_1 |
W m-2 | LW_IN |
| Vapour pressure deficit | VPD_T1_47_1, VPD_T1_47_1_HOMOGENIZED |
kPa | VPD |
| Precipitation | PREC_TOT_T1_47_1, PREC_TOT_T1_47_1_HOMOGENIZED |
mm (30 min)-1 | PREC |
| Soil water content (volumetric), five depths | SWC_FF1_<depth>_1, and SWC_FF1_<depth>_1_HOMOGENIZED except at 0.5 m |
% | SWC |
| Soil temperature, seven depths | TS_FF1_<depth>_HOMOGENIZED_GAPFILLED |
°C | TS |
| Soil heat flux, positive into the soil | G_FF1_0.05_HOMOGENIZED |
W m-2 | G |
| Outgoing (reflected) shortwave radiation | SW_OUT_T1_47_1 |
W m-2 | SW_OUT |
| Outgoing (emitted) longwave radiation | LW_OUT_T1_47_1 |
W m-2 | LW_OUT |
Column suffixes: _HOMOGENIZED is corrected for sensor changes, so the record is consistent over time; _gfXG and _GAPFILLED are gap-filled. PREC, SWC, TS, G, SW_OUT and LW_OUT end on 31 December 2025 and are empty in 2026.