HydroScat 6

Introduction

Using the HydroScat

Calibration

Data processing
This section briefly describes some issues we have encountered using the HydroScat.


For detailed instructions on deployment and instrument maintenance please refer to the Hydroscat manual.


Mounting issues:

The picture on the right shows the HydroScat mounted on our SlowDROP platform. It is of course required to not obstruct the field of view the instrument. Hobilabs recommend to keep a cone of 30 degrees free of obstacle for a distance of 1 meter from the face of the unit. Avoid metal to metal contact when mounting the HydroScat on a frame.

Setup issues:

There are numerous logging parameters that can be changed. The settings are saved in the
instrument memory. We usually setup the instrument directly through a terminal program
but hydrosoft can be used as well. Below are some tips to avoid common mistakes:

  • The AGAIN (auto gain) function must be on (1) during a deployment. The calibration
    procedure requires the AGAIN function to be switched off. So there is a risk that the
    autogain be accidentally left off after the calibration.

  • When running the instrument on external power through a data logger (like Modaps or HydroDAS):
    1- Make sure you set the SleepOnFull function to 0. If on 1 the instrument will stop
    logging data when its internal memory gets full, even if the data is actually collected
    externally. The internal memory can gets full on a very long cast or if old casts still in
    the memory were not deleted prior to the deployment. The SleepOnFull function can
    be set though the LOG command.
    2- Make sure the AUTOSTART function is on 1. The instrument will then start logging
    as soon as external power it switch on.
    3- If changing the the LOG parameters or turning on/off the florescence channels make
    sure you make these changes nonvolatile with the STORELOG and/or STOREFL
    command.

Data Issues:

The data obtained from the 676 channel should be used with caution. 676 nm light stimulates fluorescence. Because of large optical filter bandwidth (~20nm FWHM), part of the scattering picked up by the 676 channel comes actually from stimulated fluorescence emission at a slightly longer wavelength. The fluorescence contribution to the backscattering signal can be significant.

ac-9 | safire | hydroscat-6 | spmr | tsrb | modaps

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Environmental Optics - 1999