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Basic Overview


The NCAR Integrated Surface Flux System (ISFS) is designed to study exchange processes be- tween the atmosphere and Earth’s surface. This includes the direct measurement of fluxes of momentum, sensible and latent heat, trace gases and radiation, as well as standard atmospheric and surface variables. With multiple sensors and data systems, measurements of horizontal and vertical gradients also can be made.


The ISFS makes measurements in three broad categories: basic meteorology, turbulence and surface fluxes, and the surface energy balance (including radiation and soil characteristics). To address multidisciplinary research problems, the ISFS is designed for both short- and long-term deployments at a variety of sites. It achieves this flexibility through its use of solar power, its ability to communicate wirelessly, and its variety of tower types. The ISFS sensors are a mix- ture of commercial and in-house designed instruments. The ISFS also integrates a microproces- sor with front-end electronics into each sensor, creating an intelligent sensor with individual calibration information, simple interfacing, and data output in calibrated engineering units.


Basic Meteorology Sensors


Basic meteorological measurements include pressure, temperature, humidity, horizontal wind speed and direction, and precipitation. Pressure, temperature, and humidity are measured at the World Meteorological Organization standard height of 2 meters (and winds at 10 meters) in the network configuration of the ISFS.


Flux Measurement Sensors


Flux measurements made by the ISFS utilize the eddy-correlation technique. This requires sensors with fast sam- pling that can respond to fast changes in the atmosphere.  Momentum flux is determined from the covariance between the vertical and horizontal velocity fluctuations measured by the 3D sonic anemometers.


 Sensible heat flux is determined from the covariance between measured vertical velocity and virtual temperature fluctuations also measured by the sonic anemometer.


 Latent heat flux is determined from the covariance between measured vertical velocity and humidity fluctuations.


Typical Research Applications


This facility is flexible and has been used in a wide range of climates, from arctic to desert con- ditions. The ISFS combines the ability to be configured as a network of surface weather stations with the ability to support intensive micrometeorological research at a single site. Investigators can configure ISFS resources to match the research objectives of each field project.


Surface Energy Balance Sensors


The total surface energy balance is measured by combining the sensible and latent heat flux mea- surements with radiometers and soil heat flux mea- surements. The net radiative forcing of Earth’s sur- face is measured either by net radiometers or by subtracting the outgoing from the incoming radia- tion both in the visible and infrared wavelengths.


The ISFS has soil heat flux sensors that are typi- cally deployed at a depth of five centimeters to capture the diurnal cycle of heating.


Contact


ISF Manager Dr. Stephen Cohn cohn@ucar.edu 303.497.8826


Lead Scientist Dr. Thomas Horst horst@ucar.edu 303.497.8838


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