We developed an in-situ particle image velocimetry (PIV) system, called RPiPIV, which is operated on a Raspberry Pi system. RPiPIV system is a versatile underwater equipment that is capable measure bubbles (size, shape, and rising behavior) and oceanic flows (velocity and turbulence) in two separated modes. We integrated RPiPIV onto ROV Jason, which allowed us to control the PIV and take measurements at 550 m seafloor from the control van. 

The PIV camera was also used to sample bubble size distribution using shadow imaging. The white background plate was used to diffuse light to ease post image processing.

This photo shows the 'laser sheet' in front of the camera to demonstrate PIV operation.

We need to turn of the light on the ROV to carry out PIV measurements. This makes the control van look very entertaining. We even put on some music. 

Close to the end of research cruise, the PIV system was configured into a self-contain mode for a planned 3+ month measurement. The entire PIV system was powered by an Alkaline battery package. The PIV was scheduled to wake up for 15 min every 5 hours (15 min duty on, 4 hr and 45 min duty off). During duty on time, the PIV algorithm was executed for 10 min. This will give us  time series data for a few months to evaluate the temporal variability of natural seeps. 

We had our group photo near the end of research campaign (photo credit to Sarah Kirk).