CSAT3A
CSAT3A
Orderable3-D Sonic Anemometer, Head Only
Overview
The CSAT3A 3-D Sonic Anemometer is the 3-D sonic anemometer of choice for eddy-covariance measurements. It has an aerodynamic design, a 10 cm vertical measurement path, operates in a pulsed acoustic mode, and withstands exposure to harsh weather conditions. Three orthogonal wind components (ux, uy, uz) and the speed of sound (c) are measured and output at a maximum rate of 50 Hz. The CSAT3A head is operated by the EC100 electronics, which also control either an EC150 or EC155 gas analyzer.
Measurements can be triggered from two sources:
- Data logger’s SDM command
- EC100’s internal clock
The SDM protocol supports a group trigger for synchronizing multiple CSAT3As.
Key Advantages
Best instrument for flux and other high-level turbulence research projects
Technical Description
The CSAT3A is an optional component of an EC150 open-path or EC155 closed-path CO2/H2O gas analyzer. It attaches to a common mounting bracket and connects to the gas analyzer's EC100 electronics module.
Benefits
- New conformal coating helps protect sonic transducers in corrosive environments
- Innovative design provides precision turbulence measurements with minimal flow distortion
- Usually combined with EC150 or EC155 gas analyzers giving near complete colocation for eddy-covariance measurements
- Compatible with most Campbell Scientific data loggers
- Measurements can be used to calculate momentum flux and friction velocity
- Campbell Scientific’s fine wire thermocouples are an option for fast-response temperature measurements
- Field rugged
- Innovative signal processing and transducer wicks considerably improve performance of the anemometer during rain events
- Sealed sonic transducers and electronics
Specifications
- Measurement Path Length
- 10.0 cm
(3.94 in.) vertical
- Measurement Path Length
- 5.8 cm
(2.3 in.) horizontal
- Path Angle from Horizontal
- 60°
- Construction
- Sealed sonic transducers and electronics
- Anemometer Head Materials
- Stainless-steel tubing
- Electronics Box Materials
- Welded aluminum
- Operating Temperature Range
- -30° to +50°C
- Voltage Supply
- 10 to 16 Vdc
- Current
- 200 mA
(60 Hz measurement rate)
- Current
- 100 mA
(20 Hz measurement rate)
- Digital SDM Output Signal
- CSI 33.3 k baud serial interface for data logger/sensor communication.
(Data type is 2-byte integer per output plus 2-byte diagnostic.)
- Support Arm Diameter
- 1.59 cm
(0.63 in.)
- Transducer Diameter
- 0.64 cm
(0.25 in.)
- Transducer Mounting Arm Diameter
- 0.84 cm
(0.33 in.)
- Anemometer Head Dimensions
- 47.3 x 42.4 cm
(18.6 x 16.7 in.)
- Anemometer Head Weight
- 1.7 kg
(3.7 lb)
Measurements
- Outputs
- ux, uy, uz, c
(ux, uy, uz are wind components referenced to the anemometer axes; c is speed of sound.) - Speed of Sound
- Determined from three acoustic paths; corrected for crosswind effects.
- Measurement Rate
- Programmable from 1 to 60 Hz, instantaneous measurements.
Two over-sampled modes are block averaged to either 20 Hz or 10 Hz.
- Output Bandwidths
- 5, 10, 12.5, or 20 Hz
- Output Rate
- 10, 20, 25, or 50 Hz
- Measurement Resolution
- Resolution values are for instantaneous measurements made on a constant signal; noise is not affected by sample rate.
- Measurement Resolution
- 1 mm/s rms
(ux, uy)
- Measurement Resolution
- 0.5 mm/s rms
(uz)
- Measurement Resolution
- 15 mm/s (0.025°C) rms
(c)
- Offset Error
- Offset error and gain error values assume the -30° to +50°C range, wind speeds of < 30 m/s, and wind angles between ±170°.
- Offset Error
- < ±8.0 cm/s
(ux, uy)
- Offset Error
- < ±4.0 cm/s
(uz)
- Gain Error
- Offset error and gain error values assume the -30° to +50°C range, wind speeds of < 30 m/s, and wind angles between ±170°.
- Gain Error
- < ±2% of reading
(wind vector within ±5° of horizontal)
- Gain Error
- < ±3% of reading
(wind vector within ±10° of horizontal)
- Gain Error
- < ±6% of reading
(wind vector within ±20° of horizontal)
- Rain
- Innovative ultrasonic signal processing and user-installable wicks considerably improve the performance of the anemometer under all rain events.
Digital USB and RS-485 Output Signal
- Baud Rate
- 230400 bps
(maximum)
- Data Type
- Comma-delimited ASCII
SDM, USB, & RS-485 Digital Outputs Reporting Range
- Full-Scale Wind
- ±65.535 m/s autoranging between four ranges
(Least significant bit is 0.25 to 2 mm/s.)
- Speed of Sound
- 300 to 366 m/s
(-50° to +60°C) Least significant bit is 1 mm/s (0.002°C).
Ships With
(1)- 29191
CSAT3A Foam Case Set
Orderable
Related Resources
Case Studies

Korea: Flux Monitoring over a Rice Paddy
Eddy covariance fluxes and vertical profiles of methane, carbon dioxide, and water vapor
Seoul, Korea
January 25, 2013
View
Alaska: Eddy Covariance
Measuring eddy-covariance fluxes in cold-climate forest
Bonanza Creek Experimental Forest (a National Science Foundation Long-Term Ecological Research site in the Alaska interior)
June 19, 2013
View
British Columbia: Forest Carbon Sequestration
Long-term eddy-covariance assessment of carbon sequestration in forested land
Vancouver Island, British Columbia, Canada
April 17, 2013
View
Documents
- Brochure
CSAT3A 3D Sonic Anemometer
March 2026
View Document - Technical Paper
Eddy Covariance Hardware Troubleshooting — Preparing for a Site Visit
June 2026
View Document - Manual
EC150 CO2 and H2O Open-Path Gas Analyzer and EC100 Electronics with Optional CSAT3A 3D Sonic Anemometer
February 2026
View Document - Compliance
CSAT3A EU Declaration of Conformity
View Document - View all documents
