Can you please guide me to some good schematics and pictures showing the configurations of the PAR and Eco Puck (CDOM, bb, Chl) sensors on the slocum gliders? I need to be able to view how these sensors are mounted so I can understand possible sources of error, such as (1) degree of pitch that is too great for accurate PAR measurements, and (2) whether air bubbles can get trapped in sensor area of the eco puck and cause spuriously high backscatter.
thanks.
If you go to the gliders OOI webpage image, you’ll see the PAR ball on the gliders just behind the recovery bale within the black section. I believe for the PA gliders they still use that bale for recovery, but I could be wrong. Someone at OOI would need to provide distances between the sensor and possible shadow sources, although I would imagine they are negligible. I’m fairly certain that the PAR and ECO only sample on the down yo. Effort is also made for the dive to be at an angle of 26 degrees for the Slocum G2s.
The ECO Puck is located on the starboard side of the gliders that are in the coastal array configuration. I don’t know the exact angle of sensor, but I don’t think it sees the glider wing or body. I believe they are oriented so that the sensor and light sources point away from any portion of the glider. I think it is unlikely that air bubbles would get trapped in the sensor area, even along the edges of the copper plate. And if there were some trapped bubbles after a surface call, I would image they would dissipate after the first dive or two given the roll changes the glider experiences during a dive.
I’ve attached some images of Endurance Array gliders. I found these on the OOI Alfresco under
Coastal Endurance Array > Cruise Data > small_boat_20171206_PS > pix20171206.zip.
Typically, just before deployment and just after recovery, images of the glider are collected. However, they are not always uploaded to Alfresco. You will need to request any images that were taken for the gliders/deployments of interest.
Biofouling may also be a concern.
I am not aware of the biofouling extent on PA gliders, but on EA gliders you will sometimes see small gooseneck barnacles on the PAR ball at the end of a 3 month deployment.
