Gas Flux and Turbulence

Campbell Scientific offers research-grade instruments for micrometeorology applications, including measurement of sensible heat, water vapor and trace gas fluxes, and atmospheric variables required by air-quality dispersion models. We also offer a variety of automated weather station configurations.

Micrometeorology System Benefits

• Eddy-covariance systems are based on a stand-alone Campbell Scientific datalogger; they compute fluxes on line and archive raw measurements for post-field analysis.
• Systems are compatible with most sensors.
• You can add sensors and configure systems to meet specific applications.
• A variety of telecommunication options support remote data retrieval and system verification.
• System provides reliable operation over the environmental temperature range.
• Batteries and solar panels support long-term operation.

Surface Flux Measurements

Our flux systems can measure atmospheric gradients or vertical turbulent transport directly. Standard systems that support either aerodynamic or Bowen ratio gradient techniques are available for measuring heat, water vapor, and CO₂ fluxes. Our standard eddy-covariance systems use a three-dimensional anemometer and either an open-path krypton hygrometer or Campbell Scientific's EC150 open-path H₂O and CO₂ analyzer. Measurements of other trace gas fluxes, such as N₂O and CH₄, are obtained with our TGA200 tunable diode laser analyzer.

Trace Gas Measurements

Using tunable diode laser absorption spectroscopy, the TGA200 Trace Gas Analyzer has the sensitivity to measure ambient gradients of trace-gas species such as N₂O, NO₂, NH₃, CH₄, and CO₂, and a frequency response sufficient for eddy-covariance applications. The TGA200 is a rugged, portable instrument designed for field use. The system PC, requiring protection from the environment, can be located 100 m or more from the analyzer. The TGA200 supports valve switching for profile or gradient measurements from multiple sites. When used in eddy covariance applications, several data-acquisition options are available. Analog signals can be digitized at 10 Hz by the TGA200 and stored with concentration measurements in the PC; using a Campbell Scientific datalogger, TGA200 measurements are synchronized with other flux sensor measurements and stored in the datalogger.

Sampling Systems for Concentration Profiles

Campbell Scientific designs and manufactures sophisticated sampling systems for measuring trace gas profiles from multiple sites with a single analyzer. Simultaneous measurements of multiple gas species are possible using multiple analyzers. Operating techniques and the use of low-volume manifolds minimize the equilibration time after intake switching. The system response, even for low flows, permits measurement of eight-levels in one minute, eliminating the need for averaging volumes. Elimination of condensation in unheated sample lines provides an additional benefit.

Meteorological and Air Quality Measurements

Our automated weather stations, known for their reliability and on-site processing, are used world-wide to record air temperature, relative humidity, wind speed and direction, precipitation, atmospheric pressure, solar radiation, and other variables. Air quality stations configured with 10-m towers provide measurements that meet the U.S. Environmental Protection Agency's guidelines for use in dispersion modeling. Means and standard deviations of wind speed and direction are processed by the datalogger, and temperature gradients used in determining atmospheric stability classes are provided. Further information on these applications is provided at our Weather and Climate, and Air Quality Solutions pages.

System Components

Dataloggers used in Micrometeorology

Our dataloggers, world-renowned for their reliability, integrate the measurement, processing, data storage, and control functions required by micrometeorological field systems. Measurement types, scan rates, and recording intervals are programmable. External devices such as valves and samplers are controlled based on time or measured values, and a powerful set of on-board instructions and algorithms process measurements on-line. All of this is provided by a low-powered, rugged set of electronics operable over the full environmental temperature range.

Sensors and Analyzers

Most sensors and analyzers, even those made by other manufacturers, interface directly to our dataloggers. Common sensors used in our micromet systems include sonic anemometers, hygrometers, fine-wire thermocouples, and open- and closed-path gas analyzers, including the EC150 and EC155. A wide variety of meteorological and soil sensors can also be used.

Data Retrieval

In addition to on-site data storage, multiple telemetry options provide remote data collection and system verification. Land line and cell phone, RF, phone-to-RF, and Internet communications are supported by our PC software. Extended line-of-sight RF, GOES, and other satellite options are supported by our datalogger software.

Add energy balance or biomet sensors, such as:

HMP155A
Temperature and Relative Humidity Probe NR-LITE2
Net Radiometer NR01
4-Component Net Radiometer CNR4
4-Component Net Radiometer TCAV
Averaging Soil Thermocouple Probe CS616
Water Content Reflectometer CS650
30 cm Soil Water Content Reflectometer CS655
12 cm Soil Water Content Reflectometer HFP01
Soil Heat Flux Plate HFP01SC
Self-Calibrating Soil Heat Flux Plate