Ultrasonic Anemometers

We provide the only true, orthogonal ultrasonic anemometer.  This new Sonic Anemometer/Thermometer incorporates all of the features from earlier models, using state-of-the-art microprocessor and surface mount technologies. Software that computes the wind velocities has been enhanced and optimized to provide a rapid response ultrasonic anemometer/thermometer.

The electronics that operate the Sonic Anemometer/Thermometer are located in the probe array. Typically, the Sonic Anemometer/Thermometer is DC powered, however other power options are available by either external adapters or by contacting the factory. The Sonic Anemometer/Thermometer is usually connected to a computer running a terminal emulation program, or can be connected directly to a dumb terminal. The Applied Technologies, Inc. Sonic Anemometer/Thermometer is a stable, low powered anemometer, capable of running unattended for extended periods of time.

The system may include: single, double, or triple axis probe arrays, along with several other novel probe array designs. These designs reduce errors from both flow asymmetry and interference from structural members.

The system detects wind velocity components along mutually orthogonal acoustic paths, computes the wind velocity and provides an output directly in engineering units. The probe array designs of the Applied Technologies, Inc. Sonic Anemometer/Thermometer are the only TRUE orthogonal ultrasonic anemometer and provides a true vertical velocity measurement. The "W" component is not inferred or calculated from some other measurement, but is a direct measurement that has an alignment accuracy of better than ±0.1°.

The system also provides calculations necessary to compute the sonic temperature, (in the "W" path), corrected for velocity contamination. It provides these data with excellent frequency response and makes it ideal for many aspects of basic atmospheric research, along with any requirement for a very accurate temperature.

These ultrasonic anemometers are ideal for use in systems measuring the eddy covariance method. (also know as Eddy Correlation and Eddy Flux).  This is an atmospheric measurement technique used to calculate vertical turbulent fluxes within atmospheric boundary layers.

Ultrasonic Anemometer General Information

The Ultrasonic Anemometer / Thermometer is an microprocessor based wind sensor capable of measuring wind velocity in one, two, or three axes with reliable accuracy. Ours is the only true, orthogonal ultrasonic anemometer.

The instrument is designed to measure wind velocity components by transmitting and receiving ultrasonic signals along fixed orthogonal directions. The microcomputer electronics then processes this information and calculates the wind speed in three axes (3D). Since there are no moving parts to come into dynamic equilibrium with the air flow, the Ultrasonic Anemometer responds rapidly to wind velocity fluctuations. It responds linearly to wind velocity and is free from contamination from other velocity components as well as pressure, temperature and relative humidity. The calibration of the sensor is established by it's design parameters, and therefore, can be used as an absolute instrument.

The probe array was designed to minimize flow distortion created by a supporting base and to permit a very wide unobstructed coverage of the vertical component. The probe array may be oriented in any direction, but ideally, the vertical axis is mounted on the upwind of the two horizontal axes.

The transducers are piezoelectric crystals and completely sealed for rugged outdoor operation. The electronics are all contained in the probe bar. This allows it to be operated as a tower mounted instrument, capable of withstanding hostile environmental conditions. The transducer operation and ultrasonic functions, as well as all computation and transmission of data, are under microprocessor control.

Data from the Ultrasonic Anemometer are serial digital. The output is RS-232C compatible in a UART asynchronous format. It represents the data in ASCII decimal numbers, and may be connected directly to a computer, transmitted to any digital recording device, or the format is such that it can also be read directly on a terminal. The temperature information is the ultrasonic temperature of the measured winds and is calculated from the vertical ultrasonic measurement.

Features:
  • Single component wind velocity
  • Fast response wind velocity
  • Fast response temperature
  • Extremely Accurate
  • Microprocessor based
  • Solid-state digital operation
  • No moving parts
  • Unattended operation
  • Ease of mounting
  • Rugged construction
  • Low power
  • DC powered
  • True orthogonal measurements
  • 3D winds
Functions:
  • Ability to do remote commands through the serial port
  • Perform internal calibration to maintain accuracy
  • User programmable data rates and averaging, from 1 output per 60 minutes to 200 Hz
  • Select between 'data averaging' or 'median' filter
  • Select from several output formats
  • Select from several baud rates
  • Synchronize ultrasonic operation to external trigger
  • Ability to output a 'trigger' pulse for other instruments
  • Select the output 'speed of sound' and/or 'temperature'
  • Enter a known RH value for a more accurate temperature output
  • User adjustments to temperature calculations
  • Change horizontal velocity to wind speed and direction, while retaining vertical temperature
  • Turn flow distortion correction 'on' or 'off'
  • User adjustments to flow distortion calculations