Suite of Instruments (Part two)

Tomorrow looks to be a marathon day. We’re arriving at the station and dealing with the old and new Waveriders. The time will be mostly spent taking in and letting out the more than two miles of cable needed to anchor the instruments to the sea floor, so during that period we’ll also be firing up the cameras and throwing out some SWIFTs (see my last post on these stalwarts of our instrument fleet). I wanted to fill in the gaps from that last post and just mention some of our auxiliary tools.

Sonic Anemometer: This instrument measures wind speed, pure and simple. It’s a classic measurement tool, and between the ones already on the ship, the ones on the SWIFTs, the one on the Pan and Tilt, and the main one we mounted right at the front of the ship (pictured), we’ve got this pretty much covered. “Sonic” anemometers measure windspeed from the disturbances of ultrasonic pulses, and unlike other types of anemometers, they have the advantage of having no moving parts. We also put an accelerometer nearby the main anemometer to correct for the ship’s motion and get an even more accurate measurement, which is necessary for turbulence calculations.

Helikite: So I don’t know if that’s technically the proper word for this instrument, but I’m using it anyway. We usually just call it “the balloon”, or, occasionally, “the angry marshmallow”. Basically it’s a big helium balloon with a a helmet camera and a GPS unit on it that we fly like a kite. This is a poor man’s version of an instrument platform designed by other researchers at APL (Andy Jessup, Chris Chickadel, et al), only theirs has stabilized video and much more expensive (and heavy) hardware onboard, so in turn it also needs to be much bigger. We get great, wide shots of the sea surface from these videos, but we have yet to show that we can measure whitecaps from them in the same way we have from the shipboard cameras. We’ll just call this one an “up and comer.”

Mixed Layer Float (MLF): This instrument is courtesy of Eric D’Asaro, another researcher at the Applied Physics Lab, and one of many iterations of the float, which is designed and fabricated in house. They can spend months at a time drifting freely in the open ocean. They get their name from the depth region they hang out in: the mixed layer is the very upper part of the ocean, where density is roughly constant. These floats are neutrally buoyant, so they follow the small upward and downward currents of the mixed layer and chart their own progress. They also can be outfitted with a number of other sensors and instruments. Today we picked up the MLF that had been deployed around Station Papa, so you likely won’t hear about it much more.

CTD (Conductivity, Temperature, Depth) Sensor: The name says it all. That’s what it measures. This is a classic oceanography tool for characterizing the “water column” (I.e. from the surface to ocean floor). The ship’s CTD platform is also capable of taking water samples from a series of depths, which is what we used it for today (again, this one’s now done so you won’t hear any more about it). We collected water samples for Mike Dodd, a professor in Civil and Environmental Engineering. To be honest, I’m not sure what the plan is for the samples, I just wanted to mention this cool instrument.

I think that’s all of it. It might not seem like much, but when we’ve got everything up and running, it sure gets hard to keep track of it all. Now if only we could get some waves…

– Mike


One thought on “Suite of Instruments (Part two)

  1. Sue Havlicek

    Hi Mike,
    Enjoyed your blog. I did understand the part about what you had for dinner, but that’s about all my simple mind comprehended. Also, would love to see the graham cracker and Hershey bar to go with that giant marshmellow!!!! Stay well,

    Aunt Sue



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