Shipboard ADCP (SADCP)

Data collection and setup

• Quick cartoon explanation of how ocean currents are measured from Shipboard ADCP (U of Hawaii)

Note

The KPH previously used the VmDAS SADCP aquisition system, but has in later switched to UHDAS - which generally gives better results, is better supported, and is easier to use. It is possible to process legacy VmDAS data in the UHDAS system; this first requires a conversion step.

Post-processing

SADCP data is collected automatically on the KPH (and many other research vessels including in the IMR fleet). To obtain science- and publishing-ready data, it is necessary to run some post-processing steps to clean up and self-calibrate the data. This is a combination of automatic and manual steps.

We use the CODAS system for post-processing SADCP. It is built on Linux, so Windows users must use a linux virtual machine (VM). Luckily, a VM configured for SADCP processing can be downloaded from the UHDAS-CODAS developers.

There is excellent documentation for CODAS/UHDAS SADCP system, including

• Data post-processing

• Examples/troubleshooting

Post -processing consists of:

• Manual editing

  • patch_hcorr.py - patching holes in heading correction (should not nbe neccessary here)

  • dataviewer.py - editing out bad data, sub-bottom pings, etc

• Data calibration

  • quick_adcp.py (calibration based on the data - do iteratively after editing)

• Generating products (netcdf and other data products)

  • For publishable data from NPI cruises, we need to make some modifications to structure and metadata to create a final, orderly, and CF-compatible .nc file.

Possibly useful

• Notes from trying to process legacy KPH cruise VmDAS data using UHDAS
• Some notes from e-mail correspondance with SADCP/UHDAS expert Jules Hummon (U of Hawaii)