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LI-7500 Open Path CO₂/H₂O Gas Analyzer

A Novel Design In an Analyzer for Eddy Covariance Studies

The smooth, simple, aerodynamic profile of the LI-7500 Open Path CO2/H2O Gas Analyzer belies the innovations within - optics, electronics, and software - that allow fast, precise measurements of in situ densities of CO2 and H2O in turbulent air structures.  In eddy covariance studies, these data are used in conjunction with sonic anemometer turbulence data to determine the fluxes of CO2 and H2O. Applications include determining the carbon dioxide and water vapor budgets of agricultural or natural landscapes such as forest canopies, grasslands, deserts, oceans, etc. for global change and ecological studies.

The novel open path design provides a number of benefits over other flux measurement systems, including:

• High speed and precision.
• Low power consumption, so that in remote environments the LI-7500 can be powered by batteries or solar panels.
• Absence of internal or external tubing allows for undamped measurements of CO2 and water vapor fluctuations, and no time delays
• A sealed sensor head with sapphire optical windows allows operation in harsh environments at temperatures ranging from -25 to 50 °C (-40 to 50 °C is also possible - consult LI-COR).  In addition, the lightweight LI-7500 sensor head can be mounted in virtually any desired orientation.
• A weatherproof box houses the control unit's high speed Digital Signal Processing (DSP) electronics.  Serial data are output at selectable speeds of up to 20 Hz, and linearized, user-configurable Digital-to-Analog Converters (DACs) output analog signals, which are updated at 300 Hz.
• A simple Windows® interface software provides for easy setup, calibration, and monitoring.  In addition, the software provides:
• Real-time graphical data output.
• On-board diagnostics to alert the user to potential problems that can compromise data.
• User-programmable Delay Time feature to synchronize CO2 and H2O data with data from sonic anemometers.

Why should you consider the LI-7500 Open Path CO2/H2O Gas Analyzer? (learn more...)

Photo courtesy of Campbell Scientific.