Modified

27 October 2026

Overview

The CH-LAE flux product holds the half-hourly ecosystem fluxes and meteorological data of the mixed forest site CH-LAE (Site information). The current version is FP2026.1, released on 27 October 2026 and available on request from the Grassland Sciences group, ETH Zurich. Release details are in Dataset Versions.

What FP2026.1 contains

Table 1: FP2026.1 at a glance.
period 1 January 2016 00:15 to 30 September 2026 23:45
time step 30 minutes
timestamp TIMESTAMP_MIDDLE, the middle of each half-hour, in UTC+01:00 all year (no daylight saving)
size 188,448 half-hours, 548 variables
files CH-LAE_FP2026.1_2016-2026.09 as parquet and CSV, and an _INFO.md file with the unit and description of every variable
  • Fluxes from the enclosed-path LI-7200 gas analyser (IRGA72), measured from 11 January 2016: NEE, LE, ET and H, quality-controlled and gap-filled, with the random, USTAR and joint uncertainty of NEE. The full Level-1 output of EddyPro is included as well.
  • Meteorological data: thirteen products, from radiation and air temperature at 47 m to soil water content and soil temperature at the forest floor. See Meteo Data.

The column names and units are listed on Variables. Use the columns gap-filled with XGBoost (_gfXG); the MDS columns (_gfMDS) are included for comparison only. MDS fills long gaps poorly: in April and May 2016, after the start-up period of the analyser was removed, it gives an NEE of -235 gC m-2 against -113 gC m-2 with XGBoost.

How the fluxes were produced

  1. Raw data: the 20 Hz eddy covariance raw data, converted from binary to ASCII.
  2. Level 0: preliminary flux runs, used to check the setup and to choose the time-lag ranges.
  3. Level 1: final flux calculation with EddyPro, one run per setup period.
  4. The post-processing chain: Level 2 quality flags, Level 3.1 storage term (NEE only), Level 3.2 outlier removal, Level 3.3 USTAR filtering (NEE only, three fixed thresholds) and Level 4.1 gap-filling. Level 4.2, the partitioning of NEE, is not part of FP2026.1.

The dataset file is cut from a collection of all fluxes and meteorological data from 2004: 10_FLUXES_and_METEO_2004-2026.09 and 20_CH-LAE_FP2026.1_2016-2026.09.

Not yet included

  • The fluxes of the open-path LI-7500 (IRGA75), 2004 to 12 December 2017 and 17 January to 20 March 2019. They are in progress for FP2026.2, which will extend the flux record back to 2004 and supersede FP2026.1.
  • PREC, SWC, TS, G, SW_OUT and LW_OUT for January to September 2026. These columns end on 31 December 2025.
  • The partitioning of NEE into GPP and RECO.
  • A correction of LE and H for the energy balance closure.

Known limitations

  • H is missing from 10 January to 20 March 2019, and the gap-filled H in that period is model output only.
  • H in 2024 is about a third lower than in the other years. This has not been checked yet.
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