The ability to accurately measure CO2 and H2O in a vertical profile is becoming increasingly important as scientists study carbon and water cycles and their relationship to global climate change. Campbell Scientific engineers have been providing scientists advanced CO2 and H2O measurement systems for many years.
The AP200 is Campbell’s next-generation gas profile system. It is a low-power, low-cost system capable of measuring carbon dioxide and water vapor using four to eight intakes vertically, and is compatible with towers of varying height. This allows the AP200 to be used for ecosystems as diverse as forests, shrubland, grassland, agricultural systems, or urban environments. When used with an eddy-covariance flux system, the profile information gathered by the AP200 can be used to monitor fluctuations in storage term, giving a more complete picture of CO2 and H2O exchange between the surface and the atmosphere.
The new system includes a wide range in operating temperatures, automatic zero/span functions, active pressure control, and sample flow measurement. Its low power consumption makes it well suited to solar-powered applications, freeing the user from the range of the power grid. It is designed to operate autonomously for long periods, storing data in nonvolatile memory. Mobile apps are available that support field maintenance tasks such as viewing and collecting data, setting the clock, and downloading programs. If internet access is available, the AP200 supports remote status checks and data download, minimizing the number of labor-intensive, on-site status checks.
From four to eight intake assemblies are mounted in a vertical profile to a tower and connected to the AP200 system enclosure by easily installed tubes and cabling. Each intake has a mixing volume such that samples represent an average CO2 concentration at each level. Independent heaters in each intake control the condensation buildup that is common in humid environments.
The nerve center of the AP200 is a CR1000 datalogger. The CR1000 collects, processes, and stores data, switches valves from one level to the next, controls system pressure by adjusting pumping speed, monitors sample flow, regulates temperature of the pump and valve manifold, and performs automated zero/span calibration of the infrared gas analyzer (LI-COR's LI-840A).
The AP200 is manufactured and assembled in Campbell Scientific’s ISO 9001-certified manufacturing facility in Logan, Utah.