CSAT3A 3-D Sonic Anemometer, Head Only
Precision Measurements
Best instrument for flux and other high-level turbulence research projects
weather applications supported water applications supported energy applications supported gas flux & turbulence applications supported infrastructure applications supported soil applications supported

Overview

The CSAT3A sonic anemometer head is similar to the sensor head from the CSAT3 sonic anemometer, but its cable is modified to connect to the EC100 electronics. It is used as part of the EC150 open-path analyzer and the CPEC200 closed-path eddy-covariance system.

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Benefits and Features

  • 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

Images

CSAT3A lower transducer assembly top view

Specifications

Measurement Path Length
  • 10.0 cm (3.94 in.) vertical
  • 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)
  • 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.
  • 1 mm/s rms (ux, uy)
  • 0.5 mm/s rms (uz)
  • 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°.
  • < ±8.0 cm/s (ux, uy)
  • < ±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°.
  • < ±2% of reading (wind vector within ±5° of horizontal)
  • < ±3% of reading (wind vector within ±10° of horizontal)
  • < ±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).

Compatibility

Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.

Dataloggers

Compatible Note
CR1000
CR200X (retired)
CR206X (retired)
CR295X (retired)
CR3000
CR5000 (retired)
CR800
CR850
CR9000X

FAQs for

Number of FAQs related to CSAT3A: 23

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  1. No. The standard CSAT3 operating temperature is -30° to +50°C. The CSAT3 operating temperature range can be shifted by 10 degrees to cover the range of -40° to +40°C. Operating a CSAT3 with a shifted temperature range requires collecting the speed of sound and applying a different multiplier.

    With a data logger, collect the CSAT3 data with the option …Get wind & c-340 data. Compute the speed of sound using the following formula:

    where

    Ts is the CSAT3 sonic temperature;

    c is the CSAT3 speed of sound, less an offset;

    x is the speed of sound offset (337.0 for a CSAT3 with a -40° to +40°C shifted calibration);

    γd is 1.4 (the ratio of the heat capacity of dry air at constant pressure to heat capacity of dry air at constant volume); and

    Rd is 287.04 J kg-1 K-1, the gas constant for dry air.

  2. No. The offset is a function of temperature and time. Once a year, spot-check the CSAT3 wind offset using the procedure outlined in the CSAT3 instruction manual. If the measured offset is outside the specification, return the CSAT3 to the factory for calibration. To request a returned material authorization (RMA) number, follow the steps listed on our Repair and Calibration page. 

  3. Yes. If the matching layer is damaged or missing, return the CSAT3 to the factory for repair. Follow the steps listed on our Repair and Calibration page to request a returned material authorization (RMA) number. 

  4. The CSAT3 offset specification is ±8 cm/s. Therefore, it cannot be used in an application where the expected wind speed is in the range of ±5 cm/s.

  5. Yes. The bubble level can be replaced in the field using pn 31962, 1-Ring Replacement Bubble Level with Mounting Bumper and Hardware.

  6. Campbell Scientific does not offer any mounting booms or hardware that enable easy and frequent positioning of the CSAT3 sensor head. This type of hardware must be provided by the user.

  7. The sensors used in the eddy-covariance application are not compatible with SCWin. An open-path eddy-covariance program is available for purchase as pn 18442, CRBasic Basic Eddy Covariance Program. This is the program without energy balance sensors. Also available is pn 18443, CRBasic Extended Eddy Covariance Program, with energy balance sensors. To order a custom configured program, contact the Micrometeorology Flux group for assistance.

  8. No. The CSAT3 is a sensor. Time stamps are assigned to the CSAT3 data by the data acquisition system—typically a Campbell Scientific data logger or PC.

  9. Yes. The CSAT3 measurement frequency can be changed by the user. It is set by the Execution Parameter. This parameter is described in detail in the CSAT3 instruction manual in the “Datalogger Instruction Parameters” section, as well as in the “CSAT3 RS-232 Commands” section of Appendix B.

  10. The CSAT3, like other sonic anemometers, measures wind speed along the sonic path using ultrasonic signals. If the salt spray blocks the sonic path, the CSAT3 will not be able to make measurements. The same is true if a thick layer of salt is deposited on the transducer faces.