CSAT3A 3-D Ultraschall-Anemometer, nur Sensorkopf
Präzisionsmessungen
für Eddy-Kovarianzstationen und Turbulenzforschung
wetter wasser energie gas flux and turbulence bauwerke boden

Überblick

Der CSAT3-Anemometerkopf ist ähnlich dem Sensorkopf des CSAT3, aber das Kabel ist so angepasst, dass er an die Elektronik des EC100 angeschlossen werden kann. Er wird als Teil des EC150 und im CPEC200 Eddy-Kovarianzsystem verwendet.

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Funktionen und Vorteile

  • 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

Bilder

CSAT3A lower transducer assembly top view

Technische Beschreibung

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.

Spezifikationen

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).

Kompatibel mit

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

Datenlogger

Product Compatible Note
CR1000 (retired)
CR200X (retired)
CR216X (retired)
CR3000
CR5000 (retired)
CR800 (retired)
CR850 (retired)
CR9000X (retired)

FAQs für

Number of FAQs related to CSAT3A: 22

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  1. How sensitive are the CSAT3A, CSAT3AH, CSAT3B, and CSAT3BH velocity measurements to sea spray in periods of high wind speed?

    The CSAT3A, CSAT3AH, CSAT3B, and CSAT3BH—like other sonic anemometers—measure wind speed along the sonic path using ultrasonic signals. If the salt spray blocks the sonic path, the sonic anemometer will not be able to make measurements. The same is true if a thick layer of salt is deposited on the transducer faces.

  2. Are there any mounting options for the CSAT3A, CSAT3AH, CSAT3B, or CSAT3BH that lend themselves to frequent repositioning?

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

  3. What are the calibration procedures for the CSAT3A, CSAT3AH, CSAT3B, and CSAT3BH, and how are they traceable to NIST?

    The CSAT3A, CSAT3AH, CSAT3B, and CSAT3BH are calibrated over temperature for the effects of transducer delays on the wind speed, and to a lesser extent, for the speed of sound measurements.

    There is no NIST-traceable standard for ultrasonic anemometers.

  4. Is the offset relatively constant for a single CSAT3A, CSAT3AH, CSAT3B, or CSAT3BH?

    No. The offset is a function of temperature and time. Once a year, spot-check the sonic anemometer wind offset using the procedure outlined in the CSAT3B instruction manual. If the measured offset is outside the specification, return the sensor to the factory for calibration. To request a return material authorization (RMA) number, follow the steps listed on our Repair and Calibration page. 

  5. Can the CSAT3A, CSAT3AH, CSAT3B, or CSAT3BH be used in low-speed conditions, such as less than 5 cm/s? If so, what are the resolution and accuracy at these low speeds?

    The sonic anemometer 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.

  6. Is the CSAT3A, CSAT3AH, CSAT3B, or CSAT3BH anemometer measurement limited by precipitation?

    Ultrasonic anemometers are unable to make measurements if the sonic path is blocked. The path may become blocked by water that puddles on the lower transducer face or droplets that hang from the upper transducers. Sonic wicks, which come with all sonics, can be placed on the transducers to wick away moisture from the faces of the transducers. Ensure that these wicks are removed during cold conditions to prevent ice from building up around them.

  7. What is the natural frequency of the CSAT3A, CSAT3AH, CSAT3B, or CSAT3BH?

    100 Hz.

  8. Is the CSAT3/3A/3AH only compatible with Campbell Scientific data loggers?

    The CSAT3/3A/3H is compatible with three output signals: analog, RS-232, and Synchronous Device for Measurement (SDM). The sonic anemometer can be interfaced to any data acquisition system that is compatible with analog measurements or RS-232 serial communications. SDM is used with Campbell Scientific data loggers.

  9. Can a CSAT3A, CSAT3AH, CSAT3B, or CSAT3BH be used to measure wind flow angle, horizontal angle, and wind speed for the purpose of power curve testing?

    The sonic anemometer measures three-dimensional wind in a right-handed Cartesian coordinate system. From these measurements, use trigonometry to compute the wind flow angle, horizontal angle, and wind speed.

  10. Are there any corrections to the raw data (not the average data) obtained by the CSAT3/3A/3AH?

    The CSAT3/3A/3AH calibration applies a correction for transducer delay over temperature. Transducer delays cause an offset in the wind speed measurement, and to a lesser extent, an offset in the speed of sound measurement.

    The CSAT3/3A/3AH speed of sound easement is corrected for the effects of wind blowing normal to the sonic path.

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Anwendungsbeispiele

korea: flux monitoring over a rice paddy
Korea: Flux Monitoring over a Rice Paddy
With instrumentation and help from Campbell Scientific, personnel from the Department of Atmospheric Sciences at......lesen Sie mehr
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