Archive for August, 2008

Heading Northeast to the cooler water.

Saturday, August 30th, 2008

RU17 surfaced at 11, reported currents are heading northwest at 25 cm/sec. 

Altimeter says the geostrophic currents are the same direction.  We have turned the glider northeast, heading to the SST front we talked about earlier today. 

 

Moonwalks & the New Moon.

Saturday, August 30th, 2008

The SST image below shows that the track of RU17 over the past month and a half.   Most of the time the glider is flying fine, yes a bit slower that the start, but still flying.  Then there are those two periods where the glider went nowhere.  All RU17 did was spin in inertial circles for a period of a few days.  Looking at the details of the glider flight, the glider itself was spinning in 360 circles, turning to the right, so even thought it was moving up and down, and flying forward, it wasn't going anywhere but in small circles. This caused huge concern the first time, since we didn't know what was causing it, if it would end, or if we could make it go away.  We tried numerous manuevers, and even designed a new behavior, the moonwalk, where we would fly the glider backwards.  But we never got to the point of trying it, since whatever we managed to free ourselves of whatever we had snagged, and were flying again. 

 

Then comes the second event where we zoom into the glider track.  This time the glider was spinning in tight circles to the left - opposite of before. So maybe we snagged something on the other wing this time.  The tight circles turn you into an Argo drifter that just moves up and down in the water column, and we again spent several days spinning in inertial circles.  We had seen it before, and we had new beviors ready.  We flew with shallow pitches and and slow.  We held the fin steady on zero, and saw the glider spin in a constant counterclockwise circle as it ascended and descended. We continued to notice the day night cycle.  It all got worse at night, and would improve during the day.  Sometimes the improvement was a lot, sometimes very little.  We looked for ways to see if we can clean the glider every morning.  We flew steep and fast.  Not much help.  So we tried the moonwalk.  When we are at the surface and we want to descend, we pull water in the nose with the buoyancy pump, and just like the sailors in Das Boat, we through all the batteries as far forward as possible.  This gets the nose down fast and instead of just sinking down, we fly down.  But for the moonwalk, we didn't through the batteries forward.  Instead, when we pulled in the water with the buoyancy pump, we pulled the batteries all the way back so the tail was heavy.  Instead of heading down nose first, we were flying RU17 down tail first.   Our first moonwalk was only to a depth of 35 m.  We never tried it before, and people were worried we'd tear off a wing flying backwards.   But we returned to the surface, and convinced ourselves we looked cleaner than when we left (wishful thinking perhaps, but the moods in the room were noticably improved, so we left it at that).  We then tried different behaviors to try to make it through the night.  The CTD cast said the thermocline was about 30 m deep.  We tried staying shallow, flying above the thermocline overnight.  No help. The enxt day we did a double moonwalk, making sure we were as clean as possible.  The second night we tried to fly deep, again staying away from the thermocline.  If that didn't work, we were going to try drifting for the night.  But by this time, we were a few days into the event, and we were seeing improvement.  We found ourselves a mere 12 km to the southeast of what the altimetry said were some good currents.  Instead of continuing east as we were tryin to get out of this region, we turned northwest (west, everyone hates when we turn west).  Luckily it most of it was during the night so it took people a while to notice. And to our amazment, the guidance turned out to be correct, and we were heading into a favorable current to the northeast.

The most recent event above prompted many discussions on the biology.  The National Marine Fisheries Service folks from Sandy Hook stopped by the COOLroom with their collaborators from the fish acoustics world.  We talked of what fish could be out there, migrating up and down with the day night cycle, what they would find interesting with the glider or if they were just packed that tight.  And we wondered if we could hear them.  What if we had a acoustic listening device on the glider that we could turn on when we wanted to listen to fish?  The preoposal for the test flight was submitted on Friday by 5 pm. 

Oscar also talked on biolumenescence as a potential attractor.  If we are flying through layers of plankton that are bioluminescent, maybe we are glowing at night.  Meanwhile Hugh was working on the flight characteristics.  Hugh takes a lot of notes. He couldn't help but notice that the last time he was writing about these flight characteristics was one month ago.  Zooming into the first cycle just above, we went into the inertial circles on July 29, and left them August 1.  Zooming into the second cycle (two figures above), we went into the inertial circles Aug 24, and left them behind Aug 28.   So what could be happening at sea linked to the moons cycle.  Jorge Corredor from Univeristy of Puerto Rico provided the answer.  Jorge is one of our NOAA IOOS partners.  We started flying gliders with him last October. And while we were there, we talked about the bioluminescence arounf Puerto Rico.  Jorge said it was pretty azing to see, but that you have to wait for a new moon for it to be really impressive.   We googled the moon calender.

August 1 was the new moon.  So was August 31.  We checked the waves from the  Oceanweather website. The waves were low.  So just before or during the new moon, when the waves are low, we saw problems with biology.  Maybe its also time to learn more about bioluminescence.

Turning Downstream – Flight Restored.

Saturday, August 30th, 2008

Back to the blog.  You know the routine. No blog entry, something must be up.  We'll zoom into that story in the next entry.  The few days of small yellow circles in the glider track near 40.25 N, 41 W are a preview.  You can probably guess the story ...  Didn't we just go through that same thing about a month ago?  When we did get out of it, altimetric products said we were only about 12 km southeast of the stronger currents on the outer edge of eddy.  Barely a days run when you are flying.  We headed for hit, and it the edge around 1 pm yesterday.  We continued heading north till this morning, crossing into the stronger northeast currents. This morning well change the waypoint and, for the first time in a while, head downstream with them.  We are heading towards that strong Sea Surface temperature front to our Northeast.  We then have 2 potential paths to our next destination. 

The Altimetry image below shows the two paths we can take.  We are looking to get to about 36 W (the eastern edge of our present UTM navigation zone), somewhere between 39 N and 40 N.  One route follows the currents around to the north, the other follows the currents around to the south.  The south route is warmer, better for the batteries.  The northern route is colder, which we hope is better for the biology.  Everyone wants to try the northern route to see if we can catch a break on the biology. If we do, it will have important implications for the next glider we fly across.

Tracking Number for NJ to Port Hueneme 890016626

Friday, August 29th, 2008

http://www.nationalaircargo.com/

Tracking number for glider shipment 890016623

Friday, August 29th, 2008

The tracking number for the shipment of gliders to Italy is

890016623

http://www.nationalaircargo.com/

Getting Humans to the Azores

Wednesday, August 27th, 2008

After an exhaustive search, I was able to figure out a few ways to get to the Azores. Unfortunately, the only direct flight (which may be canceled) leaves from Logan International Airport in Boston, Ma. However, there are multiple direct flights from Newark Liberity International Airport, NJ to Lisbon International Airport, Portugal. Continental and TAP (Portugal National Airline).

Airline Travel

Newark to Lisbon via continental depart 8:15 pm arrive 8:20 +1day (Non-stop flight)

Lisbon to Flores FLW Airport via TAP (Portugal National Airline) Depart 6:30 Arrive 12:30-Flores Airport

OR

SATA Airline Depart 8:00 arrive 12:30

http://www.wego.com/flights/schedules/search/LIS-FLW/2008-09-17/2008-09-21/?wgz=104f4

Next we have to find boat and car rentals. That's another search for another day!

Packing List and Pictures of Tools for Italy

Monday, August 25th, 2008

Packing List and Pictures of Tools for Antarctica

Monday, August 25th, 2008

August 25 Flight Metrics

Monday, August 25th, 2008

Finding the change in the currents.

Sunday, August 24th, 2008

Yesterday we decided to fly due east to try to jump into that warm filament heading north. Wow, what a fast change in the current direction.

Time series below shows the currents steadily decrease in speed over 2 days, then suddenly flip direction by about 90 degrees from southeast to northeast.

Zooming in on the SST data, we will switch to a new waypoint that crosses the warm filament at about a 45 degree angle. Why don't we continue due east?

Altimetry below says we want to start thinking about heading north. New data was received in the region, and the high (green/yellow) we are using now is merging with the highs (red/orange) that we just left. We need to ride the boundary of the present high so we can still get out of it as we swing around its northern side. Even if we don't make it out, the consequences are not nearly as great this time as the last time. There is a pair of counterclockwise eddies located along the 38W meridian. Either of these lows (blue) will send us east.

As we are now getting used to, the altimetry seems to do a good job of explaining how we got to where we are (compare the yellow track heading southeast with the currents), but has some difficulties matching the currents where we are. But overall, it is pretty good guidance.