Navigating from Data Explorer to ERDDAP for Pioneer ADCP data, I see data for the full suite of range bins is served. This includes bins above the sea surface, and bins contaminated by sea surface interference. The variable velprof_evl does not appear to usefully distinguish good from bad data. Could we have a QC flag that would weed out the bad data - or clip it from the dataset entirely? Or is there some other recommended practise to access QC’d ADCP data.
An example from Pioneer: velocities +/- 6 m/s!
https://erddap.dataexplorer.oceanobservatories.org/erddap/tabledap/ooi-cp02pmuo-rii01-02-adcpsl010.graph?time%2Cz%2Ceastward_sea_water_velocity&time>=2021-01-01T00%3A00%3A00Z&time<=2021-04-22T03%3A00%3A00Z&z>=-871&z<=37&.draw=markers&.marker=4|5&.color=0x000000&.colorBar=|||||&.yRange=-500|50|true|&.bgColor=0xffccccff
The Pioneer Array ADCPs are upward-looking, and are configured so that the profile distance is greater than the distance to the sea surface. This allows the surface hit to be identified in the echo intensity, which may vary from deployment to deployment due to small changes in deployment location (different water depth) and may vary during a deployment due to tides and mooring tilt.
Interference from side lobes will contaminate the ADCP bins at a distance from the surface of approximately 15% of the ADCP deployment depth. A variety of publications address this issue and suggest approaches to correction (see references below).
OOI is working to implement QARTOD compliant QAQC for ADCP data provided through Data Explorer. The implementation of echo intensity test recommended by QARTOD should provide flags that will assist the user in identifying side lobe interference from the surface.
References (examples only, not exhaustive):
Kirincich, A.R., J.A. Barth, B.A. Grantham, B.A. Menge, and J. Lubchenco, 2005. Wind-driven inner-shelf circulation off central Oregon during summer. J. Geophy. Res. 110, C10S03, doi:10.1029/2004JC002611.
Plimpton, P.E., H.P. Freitag and M.J. McPhaden, 2004. Processing of subsurface ADCP data in the equatorial Pacific. NOAA Tech. Memo. OAR PMEL-125, 41 pp.
Visbeck, M. and J. Fischer, 1995: Sea surface conditions remotely sensed by upward-looking ADCPs. J. Atmos. Ocean Tech, 12(1), 141-149. doi:10.1175/1520-0426(1995)012<0141:SSCRSB>2.0.CO;2.