Jul 21

Day 5: GLAD Expedition – Fairly foul

Fairly foul weather greeted us this morning, making getting out of bed an exercise in balance for this landlubber. “We just passed through a squall,” one researcher told me as I staggered up the stairs. Uh huh.

In any case, our deployment schedule for the day is delayed until tomorrow (Sunday). But instead of displaced plans allowing the Walton Smith to list aimlessly like our 301st drifter, it came down from on high (Drs. Ozgokmen & Haus) that we survey the deployment area with CTD casts (conductivity, temperature, depth; the CTD bundle of instruments is lowered into the water either via rope or cable, sampling each of the three listed quantities to construct their corresponding vertical profiles). So, as I am writing this, our starboard winch is hauling up the fancy little device from its 1300 meter dive. This is the first of 16 CTD survey sites on a zig-zag pattern across the “S1” area (the remaining 15 will most likely be of a shallower sort- somewhere in the realm of 300 meters apiece).

CTD being lowered into the water (Photo by: Nathan Laxague)

The combination of a mildly windy, overcast day with the prospect of periods of the ship idling make this an excellent opportunity to capture meaningful surface imaging. Both the polarimetric camera and the infrared camera are being used in tandem with the CTD casts to provide as complete a picture of the water surface/column as possible. The infrared camera will pick up on surface heat flux while the polarimetric camera will focus on small (we’re talking centimeter wavelength-small) wave slope and structure- again useful in calculations involving surface roughness and gas/enthalpy transport.

Polarimetric imaging of the water surface – corresponding to linearly polarized light at zero degrees (Photo by: Nathan Laxague)


Polarimetric still – corresponds to light that has been linearly polarized at 45 degrees by the water surface (Photo by: Nathan Laxague)

Polarimetric image – corresponds to light that the water has linearly polarized at 90 degrees. Each of these three images is of the same area of water surface at the same time. The “polarization” part comes from where the image is copied twice over and each of the three are passed through polarization filters on their way to three separate cameras. This helps us re-construct the slope field associated with the small waves. (Photo by: Nathan Laxague)

Nathan Laxague signing off (somewhere between 800 and 1000 meters- “this is ourselves… Under Pressure”).