ISFF Sensor List

ISFF Measurements and Instrumentation

Standard ISFF sensors are available for the following measurements: momentum, sensible heat, and water vapor fluxes by eddy-correlation; vertical profiles of wind, temperature, and humidity; radiation fluxes; and soil temperature, soil moisture, and soil heat fluxes. The ISFF sensors are a mix of commercial instruments and in-house developments. Whenever possible, each sensor has a microprocessor that provides sensor output in calibrated engineering units through a serial communications link.

User-supplied or non-standard sensors can be readily accommodated by ISFF. Power and mounting are provided and the various data streams are easily integrated into the system.

The sensors are listed below.

Sensor Manufacturer Model Parameter Rate #
3-D sonic anemometer CSI CSAT3 u,v,w - m/s; Tvs - deg C 60sps 21
H2O/CO2 Open-path Gas Analyzer LI-COR LI-7500 H2O/CO2 concentration 20sps 5
UV absorption hygrometer CSI KH20 vapor density - gm/m3 20Hz 12
Prop-vane anemometer NCAR/SSSF - R.M. Young   U, V - m/s 5Hz 7?
Prop-vane anemometer R.M. Young 9101 U, V - m/s 5Hz ~10
Hygrothermometer NCAR/SSSF - Vaisala 50Y Humitter T - deg C; RH -% 1Hz 14?
Pressure sensor Vaisala PTB220B Pressure - mb 1Hz 9?
Net Radiometer REBS Q*7 Net radiation - W/m2 1Hz 19
Pyranometer Kipp & Zonen CM 21 Global shortwave radiation - W/m2 1Hz 8
Pyranometer Eppley PSP Global shortwave radiation - W/m2 1Hz 25?
Pyrgeometer Kipp & Zonen CG4 Global longwave radiation - W/m2 1Hz 6
Pyrgeometer Eppley PIR Global longwave radiation - W/m2 1Hz 10
Surface temperature sensor Everest Interscience 4000.4ZL Surface temp. - deg C 1Hz 10
Soil temperature sensor REBS   Soil temperature - deg C 1Hz ~10
Heat flux plate REBS HFT-3 Soil heat flux - W/m2 1Hz ~10
Soil moisture Decagon Ech2o Soil moisture - % vol 1Hz 10
Soil moisture IMKO TRIME-FM w/P3 and T3 probes Soil moisture - % vol manual 1
Soil thermal properties Hukseflux TP01 conductivity, diffusivity, heat capacity 1Hz 9
Precipitation ETI Instrument systems NOAH II w/Lexan wind screen Equivalent water depth - 0.01 inch events 3
Precipitation MRI Tipping bucket Equivalent water depth - 0.01 inch events 9+

Other ISFF Sensors that are not actively used

Sensor Manufacturer Model Parameter Rate #
3-D sonic anemometer Applied Technologies, Inc. ATI-K u,v,w - m/s; Tvs - deg C 20sps 5
3-D sonic anemometer Applied Technologies, Inc. NCAR NUW u,v,w - m/s; Tvs - deg C 20sps 5
3-D sonic anemometer Gill Instrumentation, Inc. 1012R2A u,v,w - m/s; Tvs - deg C 21sps 1
1-D sonic anemometer Applied Technologies, Inc. ?? w - m/s; Tvs - deg C 20sps 1
Platinum resistance thermometer Atmospheric Instrumentation Research, Inc. (now Vaisala) FT-1A-T Temperature - deg C 20Hz 3
IR H2O/CO2 analyzer (closed-path) LI-COR 7000 H2O/CO2 concentration 20Hz 1
IR CO2 analyzer (closed path) LI-COR 6251 density - gm/m3 10Hz 1
Infrared CO2 analyzer (closed path) RMT DX6100 density - gm/m3 10Hz 1
Pressure sensor Vaisala PTB100B Pressure - mb 1Hz 1+?
Pressure sensor NCAR   Pressure - mb 1Hz 6
Dew Point EG&G   Dew point - deg C 1Hz 1?
Soil temperature sensor NCAR ?? Soil temperature - deg C 1Hz 12?
Soil moisture CSI CS-615 Soil moisture - % vol 1Hz ~10
PAR radiometer LI-COR Quantum (LI-190SA) PAR radiation - W/m2 1Hz 6
Ultraviolet radiometer Eppley TUVR Ultraviolet radiation - W/m2 1Hz 1
Rain gauge (Optical - ORG) Scientific Technology, Inc.   Rainfall rate - mm/hr 1Hz 1
Snow depth gauge (Ultrasonic) CSI SR50 Snow depth - mm 1Hz 1
Dual beam ozone analyzer Thermo Electron 49 O3-ppb 1Hz 1
Carbon monoxide analyzer Thermo Electron 48 CO 1Hz 1
Condensation nucleus counter TSI 3760 CNC Condensation nuclei 1Hz 1

Other sensors that we've used but do not have

Sensor Manufacturer Model Parameter Rate
Soil Temperature sensor CSI CS107 Soil Temperature (C) 1Hz
Soil Potential sensor CSI CS229 Soil Moisture 1Hz

Flux measurements made by ISFF utilize the eddy-correlation technique. Momentum flux is determined from the covariance between the vertical and horizontal velocity fluctuations measured by the 3-dimensional sonic anemometers. Sensible heat flux is determined from the covariance between measured vertical velocity and temperature fluctuations. The temperature fluctuations are obtained with an Atmospheric Instrumentation Research, Inc. platinum resistance fast-response temperature sensor. Latent heat flux is determined from the covariance between measured vertical velocity and humidity fluctuations. Those humidity fluctuations are measured with a fast-response ultra-violet absorption hygrometer.

Measurement of fluxes of trace chemical species are obtained from correlating fluctuations from chemical species sensors with those from the ISFF velocity sensors. ISFF has a CO2 sensor for this purpose. Other chemical specie measurement requires user-supplied sensors which typically can be readily interfaced to ISFF. In chemical flux determination, delay times through inlet tubes can be measured and compensated for in the processing.

Tilt corrections for the sonic anemometer are applied in the software. Over uniformly flat terrain, the tilt correction puts the anemometers into a coordinate system parallel to the surface. In complex terrain, signals from two-axis level sensors are used to orient the sonic anemometers to gravity. Note also that the sonic anemometers make a virtual temperature measurement, Tvs, reported in degrees Celsius.

Mean temperature and humidity measurements are made with a hygrothermometer developed at NCAR and previously used with the NCAR Portable Automated Mesonet (PAM). These hygrothermometers are integrated sensors which utilize a platinum resistance thermometer and solid state relative humidity sensor inside an aspirated radiation shield enclosure.

Wind profiles are measured with commercial propeller-vane wind sensors which have been modified at NCAR to obtain a high resolution vane azimuth using an optical encoder. These sensors have also been modified to output a serial data string giving output in either windspeed and direction or orthogonal components.

Measurement of the surface energy balance is achieved using up-looking and down-looking pairs of short and long-wave radiometers in tandem with soil heat flux plates and soil temperature sensors. The chemical environment around ISFF sites can be monitored with sensors which measure ozone, carbon monoxide, as well as condensation nuclei.