Gone Crunchy

Since 2006 I have used the McDonalds in Sturbridge, MA as the summertime COOLroom.   Our family usually spends the first couple weeks of August and many weekends up here at our lake house in the woods on Hamilton Reservoir.  New Jersey magazine describes my hometown of Hopewell as being located in New Jersey but that it screams Vermont (in New Jersey we scream).  Hamilton Reservoir in Massachusetts is even more Vermont, with a small general store we reach by boat and the addition of cell phones only a recent annoyance. Since our entire observatory is designed to be operated from our homes over the Internet, all we need is a WiFi connection and a cup of coffee to run the entire network.  The development of this capability was required for us to support the ONR Shallow Water 2006 Joint Experiment on the outer New Jersey shelf.  We’ve been using that capability for every experiment ever since, including this one.   If necessary, you can run things over a cell modem or an IPhone, but the WiFi gives you full access to all the visualization and interactive products at a speed you can live with.  So on many summer mornings in August, you’ll find me at McDonalds in Sturbridge, right at the corner of Interstate 84 and the Mass Pike.  Until today.  The WiFi at McDonalds has been down for 2 days, forcing me to go elsewhere in search of connectivity.  Just down the street, away from the familiar setting of a highway rest-stop, I found an old house that was converted to the Sturbridge Coffee House with a free WiFi sign out front.  I found my new control center.   I’ve traded the Egg McMuffin with bacon and cheese for a vanilla muffin top with fresh raspberries.  I share the front room with other laptop users, so I am in with my own kind.  And now, through the Internet, I have the amazing privilege of spending an hour at sea.

Our glider had a difficult night.  As we said yesterday morning, we were going to try some additional tuning to the steering, and last night, we really explored the flight parameter space.  We had previously found that going slower improved our ability to track a course on the upcasts.  We adjust our speed by changing our pitch, and we found a pitch angle of 26 degrees worked well for upcasts. We also noted that over the weekend, most of our steering issues were confined to the downcast. Using what we learned from our tuning of the upcast, yesterday we also set the glider to go slower on the downcast, changing the pitch on downcast from 35 degrees to 26 degrees.  The result has been named the helo-glider, even though the apparent rapid spins were just an artifact of the plotting.  The heading error on downcast hung around 180 degrees, while on upcast it hung around 0 degrees.  The helo-glider turned out to be an excellent product for station keeping.   With that realization, Dave changed the flight parameters back to the steeper 36 degree dive on downcast, and we were back again to what we had before.  The 4 am full excursion CTD cast looked just like the previous one.

As a result we have a whole set of new parameters to send to The Scarlet Knight at noon today.  We are adding data to the science data file that comes back since we are doing good on power and we can use the additional steering info for a few of our final tuning runs.  We are setting the fin offset to zero, so we can use the full excursion of the fin in both directions to steer. We are going to try to increase the depth of the top inflection from 30 m to 35 m.  The CTD from this morning has the strongest thermocline we have seen the entire flight, about 22C at the surface and below 16 C at 40 m.  Ideally we would want to stay below this layer, but we did not like the behavior of the buoyancy pump when we inflected at 40 m.  At 40 m the pressure pushes the buoyancy pump in too fast, it generates stray electricity, and the glider shuts it down to prevent it from frying its own electronics, resulting in an abort.  It just one of the examples of how the glider knows how to save itself. The 30 m inflections look fine.  So today we’ll try something in the middle, say 35 m inflections to stay out of whatever is sitting on that thermocline.

The satellite altimetry updated this morning after skipping a day. Its shown below, and we are moving into the jet between the counterclockwise eddy to our north and the clockwise eddy to our south.  The currents reported by the glider are turning more and more to the east.  This is a good time to test parameters.  The currents are favorable, and we want to stay with them. If the currents were against us, we would be doing everything we could to fly out of them and into a more favorable region. But with tail-current, we are good to test every kind of behavior possible so we’ll know what we need to when Scarlet has to fly.  We continue east, towards Flores, and are planning for the biological sampling mission.