AWAC – 1 MHz

Real-time current profiles and directional waves for shallow water

Technical specification (PDF)

Highlights

  • Real-time current profiles to 30 m range
  • Real-time directional waves to 35 m range
  • Acoustic surface tracking (AST) with vertical beam
  • Can be used both with fixed frames and subsurface buoys

Overview

  • The AWAC 1 MHz ADCP has become the standard reference technology in submerged wave-measurement applications. Thousands of these ADCPs have been deployed to capture the full wave spectrum in combination with current profiles. With a 35 m maximum range for wave measurements and 4 Hz sampling of the surface elevation, the AWAC 1 MHz is the optimal tool for shallow current and wave measurements.

Applications

  • Online measurements of currents and waves
  • Design data for planning of new coastal structures
  • Site studies for offshore wind platforms
  • Coastal erosion studies
  • Measurement campaigns where the full wave spectrum is needed
  • Monitoring of transient waves for channel wall protection
  • Studies of tidal currents

  • Water velocity measurements

    Maximum profiling range 30 m
    Cell size 0.25-4.0 m
    Number of cells Typical 20-40, max. 128
    Velocity range ±10 m/s horizontal, ±5 m/s along beam
    Accuracy ±1% of measured value ±0.5 cm/s
    Velocity precision Consult instrument software
    Maximum output rate 1 Hz
    Internal sampling rate 7 Hz

  • Echo intensity (along slanted beams)

    Sampling Same as velocity
    Resolution 0.45 dB
    Dynamic range 90 dB
    Transducer acoustic frequency 1 MHz
    Number of beams 3 beams 120° apart, one vertical beam (90° apart, one at 5° for platform mount)
    Beam width 1.7°
    Beam width vertical beam 1.7°

  • Wave measurement option (AST)

    Maximum depth 35 m
    Data types Pressure, one velocity along each beam, AST
    Sampling rate velocity (output) 2 Hz
    Sampling rate AST (output) 4 Hz
    No. of samples per burst 512, 1024 or 2048

  • Wave estimates

    Range -15 to 15 m
    Accuracy/resolution (Hs) < 1% of measured value / 1 cm
    Accuracy/resolution (Dir) 2° / 0.1°
    Period range 0.5-50 s
    Cut-off period (Hs) 5 m depth: 0.5 sec, 20 m depth: 0.9 sec, 60 m depth: 1.5 sec
    Cut-off period (dir) 5 m depth: 1.5 sec, 20 m depth: 3.1 sec, 60 m depth: 5.5 sec

  • Sensors

    Temperature: Thermistor embedded in housing
    Temp. range -4 to +40 °C
    Temp. accuracy/resolution 0.1 °C/0.01°C
    Temp. time response < 5 min
    Compass: Magnetoresistive
    Accuracy/resolution 2°/0.1° for tilt <15°
    Tilt: Liquid level
    Accuracy/resolution 0.2°/0.1°
    Maximum tilt 30°,AST requires <10° instrument tilt
    Up or Down Automatic detect
    Pressure: Piezoresistive
    Range 50 m
    Accuracy 0.5% of full scale (optional 0.1% of full scale)
    Resolution 0.005% of full scale