Where to find ADCP velocity-shear on top/below Coastal Pioneer gliders

HelpDesk
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Hi OOI-team,

I’m searching for velocity profiles u(z,t) and v(z,t), measured by the OOI Coastal Pioneer glider ADCPs along the Eastern Boundary Hydrography Line. Here, z is the height over/below glider ADCP and u/v the velocity with respect to the glider; I expect the data to be 2D-arrays (depth x time).

I access the 1D glider time series (e.g., time, lat, lon, temp., salinity, density, etc.) via the IOOS Erddap server (ERDDAP - List of tabledap Datasets). The variable list includes 1D velocity time series “u” and “v”, but according to the description these are “depth-averaged current[s that are] an estimate of the net current measured while the glider is underwater […] calculated over the entire underwater segment, which may consist of 1 or more dives;” thus, not the velocity shear above/below the gliders I try to download.

Thank you already in advance for pointing me in the correct direction for finding the data.
Best,
Lukas

2

Hi Lukas,

We currently do not submit glider ADCP data to the IOOS Glider DAC (which would populate the IOOS ERDDAP you were looking at). The best place to access these datasets would be the OOI Data Portal (https://ooinet.oceanobservatories.org/).

You can search by reference designator on the OOI Data Portal (under data catalogue search on the top right of the page) to find these ADCP datasets. Gliders cp_335, cp_339, and cp_340 are the ones we typically deploy to the Eastern Boundary line.

The reference designators for the ADCPs on these gliders would be:
CP05MOAS-GL335-01-ADCPAM000
CP05MOAS-GL339-01-ADCPAM000
CP05MOAS-GL340-01-ADCPAM000

Searching for those should bring to the datasets you are looking for.

Thanks for reaching out and I hope this helps,
Collin

3

Hi Collin,
thank you for pointing me towards the data portal for the ADCP data. I’ve had a look at cp_335, cp_339, and cp_340 (in addition, cp_374 seemed to have occupied the EB line twice during the early phase of the Array), but only cp_340 and cp_374 list a ‘Velocity Profiler (600Hz)’ in their instrument list. Is the ADCP-data of the 335 and 339-missions saved somewhere else or weren’t all Coastal Pioneer gliders equipped with an ADCP?

Thank you already in advance for your response and support.

  • Lukas
4

Hi Lukas,

Most of our Coastal Pioneer gliders, including cp_335 and cp_339, were equipped with ADCPs. Here are the links to their data on the Data Portal:

335: Data Access & Visualization

339: Data Access & Visualization

Can you point me to the instrument list you are looking at?

Thanks!
Collin

5

Hi Collin,
thank you for your message and the links with the ADCPs listed.
So far, I’ve accessed the mobile assets data via the pathway:

https://ooinet.oceanobservatories.org >> Coastal Pioneer Array >> Mobile Assets >> Coastal Glider 335 >> (List of instruments w/o ADCP listed).
In this case, the cp_335 and cp_339 didn’t have the ADCP listed. Thus, thank you for providing the direct links.

I’ve had a first look at the ADCP data from the cp_374 glider to make sure that the files contain what I was initially wondering about and have a couple of questions about the data and ADCP setup on the gliders. I’m wondering whether you’d be willing to guide me towards sources where I could find answers to these questions or answer some of these directly?

  1. Setup:
  • Is the ADCP downward- or upward-looking? And/or: Is it correct that the gliders “only” have one ADCP looking into one direction? The variable ‘sysconfig_vertical_orientation’ is equal to 0 for the entire file.
  1. Post-processing:
  • What interpolation method has been used to calculate ‘lat’ and ‘lon’ between the gps-fixes?
  • Are roll and pitch included in the calculation of the northward and eastward velocities?
  1. Interpreting bins:
  • The variable “bin_depths” do not change over time (i.e., throughout a dive), but stay constant throughout the entire time series with depth values in the 200m-range. I guess, I could compute a momentary bin depth through the variables depth_bins = ‘depth_from_pressure’ + ‘bin_1_distance’/100 + bin_depths - bin_depths(1,:), but am wondering whether there is more meaning to the “bin_depths” variable.