Aquadopp HR-Profiler

With the High Resolution (HR) firmware option, an Aquadopp profiler can be turned into a high resolution profiler operating at sub-cm scales and with sampling as fast as 8 Hz. Targeted for use in boundary layer studies of the bottom 1-2 m and for low energy environments like lakes and estuaries, the HR-profiler excels at providing flow details that are not attainable with any other oceanographic instrument.

HR Profile photo over corals. From Jim Hench, Stanford University.

Nortek is proud to introduce the High Resolution (HR) firmware as an optional upgrade for the 1 and 2 MHz Aquadopp Profilers. The HR firmware implements a pulse-coherent processing technique that makes it possible to measure velocity profiles with vertical resolution as fine as 0.7 cm or as fast as 8 Hz. The HR Profiler is the perfect tool for bottom boundary layer studies, internal wave generation studies in lakes, under ice measurements, and in all low-flow conditions.

The HR Profiler is primarily designed for mean flow studies but the robust computational algorithms make it possible to measure also in conditions where there are significant flow variations.

 

HR Current Profiler features:

  • Measures 3D velocity profiles with 1 – 5 cm vertical resolution.
  • Can sample in continuous mode (1 Hz) or  burst mode (max 8 Hz).
  • Extended velocity range mode for use in energetic environments.
  • Software-configurable number of beams to sample: 1, 2 or 3.
  • Blanking distance reduced to 3 – 5 cm.
  • Measures to within a few cm from the bottom in down-looking mode.
  • Simultaneous measurements of velocity profiles and scattering strength.
  • Recording of data to internal recorder (352 MB) for stand-alone use.
  • Can be changed to operate in “normal” profiling mode with a firmware switch.

 

A simple download of new firmware changes the HR Profiler to be used also as a standard Aquadopp Profiler. This feature increases the flexibility and the number of applications significantly, since the same instrument can be used both for detailed studies of small scale phenomena and to obtain larger scale current profiles.

Data Examples:

HR Profiler data from Miami

Profile of vertical velocity of small surface waves measured at 8 Hz (top). Timeseries of vertical velocity from Cell 1 (0.05 m below surface) and Cell 15 (0.75 m below surface).  Click on the plot to see a larger version.

 

Special Considerations

The HR Profiler is designed for stationary applications, and is not suited for mounting on a moving ship or surface buoys. The deployment frame should be rigid to ensure that any induced motion is small.

The HR Profiler is a pulse-to-pulse coherent current profiler, transmitting short pulse pairs into the water, and calculating the phase shift between the two acoustic return signals. Nortek has developed several methods to avoid problems that arise when the phase shift exceeds ±180°, usually referred to as range-velocity ambiguity, making it possible to increase the velocity range that can be measured unambiguously. Still, there are range/velocity limitations that have to be observed and we recommend that the HR Profiler be used in conditions where the product of profiling range and the velocity does not exceed 0.5 m2/s for 2 MHz systems and 1.0 m2/s for 1 MHz systems.

Related content
File Aquadopp Profiler brochure