Accounting for Under Ice Flow Angles in SonTek RSSL

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Detailed Description

In this video we will outline the process of accounting for under ice flow angles in the SonTek RSSL software. Note: Use of trade names is for descriptive purposes only, and does not imply endorsement by the USGS. For additional videos in this series, visit the following link: https://www2.usgs.gov/humancapital/ecd/hydrotube/hydrotube-ADCP.html
 

Details

Image Dimensions: 480 x 360

Date Taken:

Length: 00:01:30

Location Taken: Augusta, ME, US

Transcript

Hi my name is Nick Stasulis and I work with the Maine Office of the New England Water Science Center. In this video we will outline the process of accounting for under ice flow angles in the SonTek RSSL software.

For under ice measurements in RSSL, the recommendation is to use the XYZ coordinate system, which requires the ADCP to be held at a fixed orientation to the tagline. The orientation, as shown in this diagram, is to have the ADCP’s connector pointing downstream and perpendicular to the tagline. This orientation has to be maintained at each station for the entire data collection period.

It’s important to highlight that if you misalign the unit with this method, it will result in apparent angles that are not real. Due to this, it’s important to monitor the ADCP and ensure it’s held steady throughout data collection at each station. Once each station is collected, it’s also important to review the software’s tables and graphs to identify potential outliers or incorrect angles that require a station to be recollected.

Also, in conditions where the ice or slush is really deep, you may not be able to see the top of the ADCP when collecting data. In these cases, it’s important to have an indicator on the rod that is secure and definitively maintains orientation to the ADCP.

When following these general guidelines, accounting for flow angles under the ice provides a much better representation of flow under ice than was possible with previous measurement techniques.