Archive for the ‘Across the Pond’ Category

Shannon & Dakota take the Wheel

Thursday, October 16th, 2008

Yesterday was one of those days a teacher never forgets.  Shannon and Dakota walked into my office in the afternoon just before heading off to class. They said they were looking at the data, and they found a better way to the Azores, and they wanted to fly it there themselves.  They were freshman when this flight started.  Now they are sophomores, part of the experienced crew. They had been learning more about the flight characteristics of RU17 this past week, and they noticed its speed had suddenly increased - after all, it is the full moon.  They also were looking at the satellite altimetry-derived current product, with its local uncertianties but generally correct features.  They drew the white line on the image. They figured they could use the new found speed to shoot the gap between two cold eddies, hugging the eddy to the northeast for a push to the east, but staying as far south as they could to catch the next set of warm eddies between 32-34 W.  They would shoot the warm eddy gap, this time hugging the warm eddy to the south for an eastward push.  Instead of approaching Flores from the north, the long term plan, they would approach Flores from the south.  The plan would cut weeks off the trip. This was important for the students.  They want to go the Azores for the pick up and turn around, so they have to get it there before finals. Saving time was critical.

We all loved the plan. Shannon and Dakota said they would take over driving and watching, just like Justin, Anthony and Eric did this past summer.  They were seniors and juniors.  Shannon and Dakato are going to show us what the sophomores can do.

 

The time series below shows the currents have decreased, but they are remaining to the east.  It looks like they are going into a region with lower currents, and a hugging the northern ring as intended. 

 

Recent sea surface temperature maps are mostly cloudy, so we forced to go to a 7 day conposite.  But when we do and we trace that same white line, we are staying in the warm water (red) south of the front.  Thats good for a few reasons.  Most of the currents on the cold side of the front (green colors) are flowing to the west.  The warmer water also extends battery life.

Battery life is something we always think about, but something that becomes even more important as winter comes. We are a few days away from 5 months at sea.  We have flown over 5,500 km.  We have less than 550 km to go to get to Flores.  9/10 of the way there.

More info about Azores trip.

Wednesday, October 15th, 2008

10/15

 

-Recieved another contact from John Wilkin, Ana Martinsfrom the University of the Azores dept. of oceanography and fisheries www.horta.uac.pt

 

-Recieved an e-mail from Raquel Toste (Hotel Manager), and replied asking about more information on lodgins, boat rental, and air travel

 

A more detailed map of Flores:

http://en.wikipedia.org/wiki/Image:Flores_Azores.png

 

The airport is on the east side of the island in Santa Cruz and Tostes hotel is just north of that also on the east coast.

 

The next island to the east is Faial, over 150 km away so the possibility of hitting any islands if we fly the glider to the east side of Flores is slim to none.  

Map of the Azores with Names

Monday, October 13th, 2008

Info On the Azores trip

Monday, October 13th, 2008

 

 

Azores Trip:

 

Important people 

     - Luis Sebatiãno - (l.sebastiao@gmail.com)

          Works at DSOR Lab at Insitute for Systems and Robotics- based in Lisbon

          Has contacts in FAIAL island

     -Renato Bettencourt

     -Mr. Toste

          Has contact at: Oceanography Fisheries Department of the University (at FAIAL island)

     -Dr. Ricardo Santos-(Director of department)

     - Renato Bettencourt

          Part of the staff that works with AUV and ASV operations

     - Mr. Toste 

          Not quite used to handling AUVs but a reliable and capable person (acc. L. Sabatiãno)

          Runs a hotel- see below

          Has a diving center

               -Bigger boat (RIB type) is about 7m long 

     - John Wilkin- (wilkin@marine.rutgers.edu)

          Has contact Alvaro Peliz

     -Alvaro Peliz 

          Friend of Ocean Modeling Group

          Can propose oceanographic scientists who could help with logistics on ground and at sea

 

Travel and Lodgings

     -Travel 

          EWR to 

               - "Ponta Delgada" airport (at "Sao Miguel" island) -approx. $1,300-$2,200

               - "Horta" airport (at "Faial" island) -approx. $1,300-$2,600

               - "Terceira" airport (at "Terceira" island) -approx. $1,300-$2,300

          With TAP airline 

               - http://www.flytap.com/USA/en/Homepage/

                    Then take an international flight between islands with SATA Airline

               - http://www.sata.pt/EUA/en/Home/

          OR BOS directly to the Azores via SATA airline

               -MUCH CHEAPER that flying TAP -$400-$500 one way

     -Lodgings

          Mr. Toste's Hotel 

               -http://www.azores.com/travel/hotel.php?id=67

               -http://www.hotelocidental.com/ (Portuguese) or http://translate.google.com/translate?u=http%3A%2F%2Fwww.hotelocidental.com&hl=en&ie=UTF-8&sl=pt&tl=en (google translation to english)

               - Tel: +351-292590100

               - Fax: +351-292590101

               - E-mail: hotelocidental@hotmail.com

 

Shooting South

Monday, October 13th, 2008

RU17 is moving rapidly to the south in strong currents between 35-50 cm/sec.  We have had 4 days of persistent southward currents since leaving the warm ring.  The disturbing part is that the altimetry says the currents should be to the east.  The good part is that eventually we will hit a cold eddy.  We know which one we want to hit, the one to our east, and thats the one we are heading for.

Time series below shows the 4 days of southerly currents.

SST imagery is clear again today, so we see some of the same features.  The new piece is the cold water that runs east-west near 39.5 N and turns north at 36W.  I've drawn a black line along its eastern side.  Is it clouds or is it real, yeah, the common question.  The difference here is the curvature, clouds are curving with the concave side to east, this has the concave side to the west.

Back to the altimetry. We know the eddies are real, but may ne in slightly different positions.  The biggest issure for us is that the altimeter says the currents at RU17 are to the east, and they clearly are not.  As long as we are going south, we are going to try to head towards the eddy to our east, and loop around its southern side.

Below is the same alitmeter image with the lines from the SST overlaid.  Red and white lines are from yesterday.  The black line is from today. Clouds or ocean, or clouds interacting with ocean fronts, its on the southern side of this eddy.  Its where we are heading. 

One other interesting point, see how the glider track is curving to the east even though the currents are mostly south and a bit west?  We suddenly noticed a doubling of the glider speed relative to the water over the last day. Where did that come from.  I did notice a near full moon last night.  Something to investgate today.

 

What we know, and what we don’t know

Sunday, October 12th, 2008

Wow, some clear satellite imagery! That was a bit of a wait.  Lets see what we can make of it.  The main thing that jomps out at you is the filament of warmer (light blue) water swirling around a cold eddy centered near 40 N, 40 W.   RU17 is just east of this eddy, and is experiencing strong currents to the south.  Since the currents on the west side of the cold eddy should be to the north, we clearly are not in the circulation associated with the one eddy we can really see.  

Below is the time series of currents, again steady south for 3-4 days.  The altimetry said we should be in a warm eddy and the currents should be to the west.  We should be going around for a second lap. Clearly we are not.

So lets go back over the analysis products and see where we stand.  What do we know, what don't we know.  First, back to the altimetry.  Here we see a warm eddy centered near 41.5N, 38.5 W.  Then a band of 3 cold eddies to the south, one centered near 40 W, the next near 38 W, and the third near 36 W.  Altimetry may get the exact shape of these eddies wrong, and may misplace them slightly, but it hardly ever gets the number of eddies wrong.  The challenge becomes finding the same number of eddies in the satellite sea surface temperature imagery.

 

The SST image is shown below with a different enhancement to emphasize the fronts in this region. The cold eddy near 40 W is clearly visible.  There is a warm patch to our north that could be warm ring we are supposed to be in. There is a curved front to our east.  And something to our south.

We can draw these lines on the satellite image as shown below. The red line is the outline of what cold be the warm eddy in the imagery.  It is consistent with the glider track.  As soon as we left the red circle, the glider stopped spinning in a loop and headed south.  The three white lines show what may be the three cold eddies.  The western most eddy is pretty certain.  The central eddy may be wishful thinking, but if I have to have an eddy somewhere, its the closest feature I can find.

Now we go back and overlay those same lines back on the altimetry product.  Starting with the warm eddy, it looks like the instantaneous SST shot from today says the warm eddy is displaced to the northeast of its location in the altimetry product.  Ok, that happens, and it is consistent with why the glider currents differ in direction from the expected altimeter currents by 90 degrees.  In contrast, the western cold eddy shown by the white line is perfectly lined up in both the altimetry and the SST. So we have a lot of certainty there, and we are also certain we are not in it.  The cold eddy to our east also appars to line up with the SST front.  The cold eddy to our south appears to line up with the front on its western side.  It looks like we have established our general eddy field, something we can use for path planning.  The biggest uncertainty however is found in that region between the cold eddy to our south and the cold eddy to our west.  This is precisely the region RU17 is in, and precisely the area that the strong southward currents are pushing us.

With the strong currents, this is where we are heading, like it or not.  Since that is the case, we will try to head into the cold eddy to our east.  If we catch it, we whip around the southern side and head north to the warm eddy that gets us to Flores.  Wish us luck and good satellites.

Now it makes sense

Friday, October 10th, 2008

Image below shows the sea surface temperature imagery around RU17 is still cloudy.  Seen a lot of that lately.  Generally southerly flows.

Current time series has been a bit distressing.   Currents drop in speed and then head to the south.  But all the currents in the altimetry are to the west. Did we exit the eddy on the southern side? If so we better get back inside, since everything south of this eddy is to the west.  All the currents to the east are up around 42N.  Without any additional guidance and only two datasets that disagreed, we had a big question in front of us, do we continue with the plan of going around the eddy on a second lap, which meant flying west, or do we ignore the altimetry and just head east.  Either direction is consitent with our usual practice of flying perpendicular to the current.  One goes for immediate gain based on what the market is doing right now, the other for long term gain based on historical performance.  We opted for historical performance and turned west.  The details may be missing, but the general flow from the altimeter is usually  right.  We also find the discrepancies tend to clear themsleves up if you wait a day or so for new data.

So we waited until morning.  In my case, I waited all night on a plane flight from Honolulu to Newark.  The waiting is sure made easier with no connection to the internet possible.  The new configuration for the eddy is shown below. Our track makes perfect sense now.  We are spinning around this eddy, and on the first time around we were too close to the center to make the jump to the smaller eddy just to the east. This time around we will try to stay more to the outer edge.

 

If we look downstream, we see a series of three warm (green) eddies, one near 39 W, one near 37W, and the third near 33W.  If we can fly this glider up to around 42 N, we can follow this current across the norther sides of these eddies then turn south down to Flores.  If the current stays as is, it will even send us southeast to the central islands in the Azores.

So after a couple days of wondering what was going on, we again have good agreement between what the altimeter sees from space and what RU17 sees on the ground.  Once again, it is a good day at sea.  Enjoy the weekend.

Lap 2 ?

Tuesday, October 7th, 2008

Shannon said it best today in class.  I liked eddies when I first learned about them, but now I hate them. Shannon is part of the undergraduate crew prepping for the trip to the Azores.   Over the last day or so, we started on our second lap heading around this eddy.  We've been in this stituation before - the trip to Halifax.  But several differences.  On the Flight ot Halifax, we had good SST imagery of the eddy.  The picture below shows that once again, it is cloudy over RU17. We had that one day last week where we saw warm water to the north and our warm filament appear to merge.  The altimeter said we had a bigger eddy than we started with, also talking merger. The other difference is that on the way to Halifax, we had a fully healthy glider.  Here we are flying slower, and its going to take us longer to fly out in the radial direction than RU15 did on the Halifax flight.  So we'll just keep moving the waypoint around and moving to the outer edge.

Below is the new altimetry product from Colorado. It shows the eddy extended much farther north than when we entered this area.  Again, merger is the likely scenario, and we definitely have a bigger eddy to fly out of.  And that's just what we'll keep doing as we come around the southern side.  Hopefully we come out above 42 N on the northern side.  if we can get across this eddy, we got another one to grab, and we start getting close to Flores.

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Monday, October 6th, 2008

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Altimetry Back Online – A Great Day at Sea

Tuesday, September 30th, 2008

Time series of currents observed by RU17 where to the north for a few days and are now turning east.  Was this a warm eddy to our north that had merged with the warm filament we were riding east?

 

Satellites looking at Sea surface temparature are still obscured by cloud cover.  No clue as to whats happening except from RU17 itself.

Until Bob Leden at Colorado restored access to the altimetry dataset over the weekend.  Justin logged in from his new grad school, Georgia Tech AUV lab, and restarted the google earth scripts. What a great shot! A large warm eddy centered near 41 N, 38 W.  We are on the northern side. And the RU17 observed currents are consistent with the satellite view from space.  We are heading east, and we know why.  It is a good day at sea. 700 km to Flores (FLW on map).