Jul 28

Day 11: GLAD Expedition – Hyperbolic Points

July the 27th has been a bit of a lull in the normal course of GLAD events. It was to be expected, of course- our current ship trajectory has us heading towards Gulfport for a second refueling/restocking. Anyway, much of the day has been spent surveying, organizing data, and (for me) sorting out a data collection issue with the UDM (our old friend the ultrasonic distance meter). Nothing to worry about, dear readers- just a hiccup that requires a little elbow grease and a few motes of patience.

Photo by: Tamay Ozgokmen

One of today’s tasks has been to periodically deploy drifters (outside the 270 allocated for S-deployments) along our path north of the De Soto Canyon. This puts them in shore-based HF (high frequency) radar range, so we can peek at surface currents remotely while our Lagrangian drifters are floating through them.

The northeastern tip of the De Soto Canyon is a happenin’ place right now- the ship’s onboard ADCP (acoustic doppler current profiler- harnessing the power of SOUND to measure FLOW SPEED, among numerous other things) put the currents at one portion of the surface at around 75 cm/s. For those among this blog’s readership who don’t swim with meter-sticks in hand, that is a rather energetic flow speed.

It is the hope of many modelers working in CARTHE that we find several so-called ‘hyperbolic’ points, where drifters initially placed close together will diverge on completely different paths. I don’t need to get too much into how this is of interest to a research consortium studying the transport of ocean-borne oil. These points would make GPS-laden drifter recovery a chore two days after launch- forget tracking down oil two months after a disaster. Those are the kind of features that we’re on the lookout for in this patch of ocean. The peaceful facade of calm waters and gentle waves belies a pattern of currents that is both chaotic and angry. CARTHE director (and fellow Walton Smith resident) Dr. Tamay Ozgokmen recently noted that the ocean models that sought to forecast oil transport in the wake of the Deepwater Horizon accident were “very, very wrong … day in and day out.” That’s a pretty unequivocal condemnation. It’s also the reason we’re out here.

Nathan Laxague signing off (somewhere between writing code in a language he doesn’t understand and screaming at another sensor).