Purchase of Eddy Covariance System for continuous measurements of CO₂, H₂O and CH₄ fluxes

DTU requires the acquisition of one complete eddy covariance measurement station for continuous, long-term monitoring of exchanges of carbon dioxide (CO₂), methane (CH₄), water vapour, heat, and momentum between an apple orchard and the atmosphere. The system will be used for research on climate impacts, greenhouse gas balances, carbon sequestration, water use, and sustainable agricultural production. The acquisition comprises a fully integrated field measurement station capable of operating autonomously under outdoor conditions throughout the year and generating high-frequency measurements suitable for eddy covariance flux calculations. The acquisition includes: • 1 three-dimensional sonic anemometer for high-frequency measurement of wind speed and wind direction. • 1 open-path carbon dioxide and water vapour analyser for continuous measurement of atmospheric CO₂ and H₂O concentrations. • 1 open-path methane analyser for continuous measurement of atmospheric CH₄ concentrations. • 1 integrated data acquisition, processing, storage, and communication system for synchronization, logging, quality control, and transfer of measurement data. • 1 meteorological measurement package comprising sensors for air temperature, relative humidity, precipitation, solar radiation, photosynthetically active radiation (PAR), net radiation, soil moisture, soil temperature, and soil heat flux. • 1 backup power and data retention system to ensure continued operation and prevent data loss during temporary interruptions. • 1 software package for data processing, quality assurance, visualization, footprint analysis, gap filling, and management of eddy covariance data. • 1 galvanized lattice measurement tower with a height of approximately 12 m, including foundation, mounting hardware, transport, and installation. The tower is required to position sensors above the orchard canopy and provide safe access for installation and maintenance. • 1 solar power system comprising photovoltaic panels, batteries, charge controller, mounting hardware, cabling, and associated electrical components required for autonomous operation at a field site without permanent grid connection. • All cables, communication equipment, sensor mounts, brackets, connectors, and accessories required for a complete operational system. DTU requires a complete Eddy Covariance system for continuous measurement of ecosystematmosphere exchanges of carbon dioxide (CO₂), water vapour (H₂O), methane (CH₄) and energy in an experimental apple orchard. The system must provide high-frequency measurements, robust long-term field operation, standardized data processing and compatibility with established international flux research infrastructures. A market assessment was performed to identify suppliers capable of delivering a complete Eddy Covariance solution that meets the scientific and technical requirements of the project. Suppliers investigated included LI-COR Biosciences, Campbell Scientific, Picarro and Los Gatos Research. Several suppliers can provide systems for CO₂ and H₂O flux measurements. However, LI-COR is the only supplier identified that can provide the required integrated Eddy Covariance platform including an open-path methane analyser, synchronized measurement architecture, integrated real-time flux processing and established compatibility with major international flux monitoring networks. The proposed system includes the LI-7700 open-path methane analyser integrated with the LI-7900 EddyFlux platform. According to the supplier documentation, LI-COR is the only supplier offering an open-path methane Eddy Covariance system with extensive field validation and long-term scientific use. The system further provides microsecond-level synchronization of instruments through Precision Time Protocol (PTP) and GPS-based clock control, which are essential for accurate flux calculations and data consistency. The system includes EddyPro, a widely adopted Eddy Covariance processing software used by international research infrastructures and flux networks, including ICOS. The software environment, data handling capabilities and compatibility with established network requirements are essential for ensuring data quality, comparability and long-term usability of the measurements generated within the project. The Eddy Covariance tower will be installed as temporary research infrastructure and will be dismantled and relocated to other research sites upon completion of the project. The tower and instrumentation therefore constitute reusable scientific infrastructure. Based on the market assessment, no reasonable alternative supplier was identified that could provide an equivalent integrated solution meeting all technical requirements for open-path methane Eddy Covariance measurements, synchronization, processing and compatibility with international flux research infrastructures and DTU therefore intends to award the contract to LI-COR Biosciences GmbH.