Eddy Covariance | |
Campbell Scientific offers research-grade instrumentation for micrometeorological applications including measurement of sensible heat, water vapour and trace gas fluxes, and atmospheric variables required by air quality dispersion models. We also offer a variety of automated weather station configurations. 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 our open-path H2O and CO2 analyser, the EC150. Measurements of other trace gas fluxes, such as N2O and CH4, are obtained with our TGA100A tunable diode laser analyser. We also offer a closed path system based around the EC155. Trace Gas Measurements Using tunable diode laser absorption spectroscopy, the TGA100A Trace Gas Analyser 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 TGA100A is a rugged, portable instrument designed for field use. The TGA100A supports valve switching for profile or gradient measurements from multiple sites. When used in eddy covariance applications, a CR5000 or CR1000 datalogger collects TGA100A data via an SDM interface, or the TGA100A can provide an analog concentration signal to an independent DAS. Sampling Systems for Concentration Profiles Campbell Scientific designs and manufactures sophisticated sampling systems for measuring trace gas profiles from multiple sites with a single analyser. Simultaneous measurements of multiple gas species are possible using multiple analysers. Operating techniques and the use of low volume manifolds minimise 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. Weather and Air Quality Measurements Our automated weather stations, known for their reliability and onsite 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 modelling. 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. Data loggers Our data loggers, 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. Data Retrieval In addition to on-site data storage, multiple telemetry options provide remote data collection and system verification. Landline and mobile 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. | |
