Eddy-covariance and LI-710 evapotranspiration measurements from paired hazelnut orchards with and without cover crops, Willamette Valley, Oregon (2024–2025)

Dataset Description

This dataset contains half-hourly eddy-covariance (EC) fluxes and paired LI-COR LI-710 evapotranspiration measurements from two adjacent hazelnut (Corylus avellana) orchard plots in the Willamette Valley, Oregon, United States. The two plots share the same soil series, irrigation system, tree age, and general management but differ in tree density (2025) and orchard-floor cover: Tower 1 is deployed in a plot with a grass ground cover (Poa annua) between tree rows, and Tower 2 is deployed at an adjacent plot kept with bare ground. Each EC tower is paired with a co-located LI-COR LI-710 mounted on a tower in an adjacent row (20 ft away) and oriented at the same direction as EC instrument, enabling direct, time and footprint-synchronous comparison of research-grade open-path eddy covariance against a low-cost, grower-oriented alternative for irrigation scheduling.

Temporal coverage

2024-07-21 through 2025-10-08 (field seasons only). Records are continuous at 30-minute resolution with the exceptions documented under "Known issues" below.

Instrumentation

Each tower is equipped with a Campbell Scientific IRGASON integrated sonic anemometer + open-path CO₂/H₂O gas analyzer at 6 m above ground, a Hukseflux NR01 four-component net radiometer, a Campbell HygroVue 10 ambient T/RH probe, a Texas Electronics TE525 tipping-bucket rain gauge, and a soil-energy-balance suite of three Hukseflux HFP01 soil-heat-flux plates with co-located Campbell TCAV soil-temperature averaging thermocouples. Each tower is controlled by a Campbell CR1000X datalogger running the Campbell EasyFlux DL program. Paired LI-COR LI-710 evapotranspiration sensors are connected to the same loggers via SDI-12.

Data products

Tower{1,2}_EC_30min_2024-2025_PST.csv — 30-minute EC fluxes (LE, H, ET, Fc, u⋆, momentum), full radiative components, soil-energy terms, meteorology, and Foken-style Steady-State + Integral Turbulence Characteristics (SSITC) quality flags, in AmeriFlux TOA5 format.

Tower{1,2}_LI710all_PST.csv — 30-minute LI-710 ET and ancillary variables at matching timestamps.

Site and instrument metadata, variable dictionaries, and processing documentation are included alongside the data.

Data processing

Raw turbulence data were sampled at the IRGASON's native rate (50 Hz through 2025-05-21, 20 Hz thereafter) and processed in real time by Campbell's EasyFlux DL. The on-logger pipeline includes: sample-level QC (sonic and IRGA diagnostic flags, CO₂/H₂O signal-strength thresholds, physical-plausibility bounds), Schotanus-Nieuwstadt-De Bruin humidity correction of sonic temperature, per-period double rotation (Tanner & Thurtell, 1969), a composite frequency-response correction (Moore 1986 cospectral models + Moncrieff et al. 1997 transfer functions for path averaging and sensor separation + van Dijk 2002 sonic-T transfer function + Massman 2000 block-averaging term), WPL density correction (Webb, Pearman & Leuning, 1980), soil heat flux with TCAV/CS655 storage above the plate (EasyFlux DL Manual, Appendix H), and Foken et al. (2004) SSITC quality flags. The published 30-min CSVs are the EasyFlux DL exact output. Tower 1 additionally provides SW_IN_corrected and NETRAD_corrected, derived by substituting Tower 2's SW_IN due to intermittent NR01 pyranometer issues at Tower 1.

Known caveats

The Tower 1 (grass) orchard was thinned to single density (20 ft  x 20 ft) during the 2024/2025 off-season, so Tower 1's 2024 growing season data represents a double-density orchard structure (10 ft x 20 ft). Tower 2 (bare) was not thinned within this dataset's coverage; its 2025/2026 off-season thinning affects only subsequent releases. Early-deployment periods (late July and August 2024) have reduced coverage and the LI-710 sensors were installed in October, 2024. The LI-710 specification cuts its flow pump at ambient temperatures below 5 °C, making winter LI-710 data unreliable. See the included docs/known_issues.md for the full list.

Funding

This work was supported by the Western Sustainable Agriculture Research and Education (SARE) program, grant GW24-003.

How to cite

Please cite the dataset using the DOI at the top of this record. A machine-readable citation block is also provided in CITATION.cff.