Archive for April, 2014

1,000 Days 20,000 Kilometers

Tuesday, April 29th, 2014

Probably the largest feat of the Challenger Glider Mission was achieved this week, as our budding fleet reached not only the 1,000th day at sea, but also flew the 20,000th km!

100020000

 

The Challenger Fleet has now succeeded in flying from the polar waters off of Iceland down to the tropical waters of the Caribbean in the North Atlantic and spanned the South Atlantic bridging Cape Town South Africa to the waters of Brazil by way of Ascension Island.

Taking a quick look at 29's progress, she is continuing to cruise through the eddy we discussed in the previous post.

apr29my0

 

Over the past couple of days, the eddy has migrated to the North, its strong southern region seemingly pushing us off course a bit as it moves through.  Contrary to that, RTOFS is showing a better developed eddy who's center is to our south, it's strong side being the northern edge that also aligns with the dip in our path.

apr29rt0

Another major event that occurred today was the final presentations for the Ocean Observatory Class- a course taught each semester by the founders of the Center for Ocean Observing Leadership, Scott  Glenn Oscar Schofield and Josh Kohut where a class of ~60 students break up into tiger teams to create their own research projects to pursue throughout the semester.  The final for the course is a research symposium held in the lobby of the Institute of Marine and Coastal Sciences where a special guest comes to review the student's research.  This semester, Dr. John Manderson of NOAA attended as the featured guest and joined a number of IMCS faculty and staff in learning of the progress the students made over the course of the semester. Click here to see some of the research conducted.  View photos from the symposium

Dr Manderson watches as a group of students demonstrates their semesters research

Dr Manderson watches as a group of students demonstrates their semesters research

Mysterious Eddy Structure

Friday, April 25th, 2014

There has been quite a buzz amongst the scientists down in Brazil as 29 makes her way south along the shelf.  The region we are presently flying through is notorious for eddy formation and researchers are keen on looking at the data as Challenger makes her way through the region.  Last week, looking at the models it seems we may have cut our way through the position of a potential eddy while we may be on the verge of entering a new one.

Looking at the forecasted structure of the water column, in the top few hundred meters there appears to be a strong clockwise spinning eddy while at depth there is a northward jet flowing along the shelf when inquiring the MyOcean model.  The RTOFS model on the other hand shows a counter clockwise spinning eddy at depth to the south east of the gliders location.  The eddy most evident in the surface layers of the MyOcean model will be a prime subject to delve into in the coming weeks.

Force Wind Sea and Honor

Positioning ourselves for the Crossing

Saturday, April 19th, 2014

ubatuba_approach

 

With just 500 km remaining between RU29 and the port of Ubatuba, our team is working to pull all of the moving parts together to make this mission a success.

By the mere luck of the draw, Dr Frederico Brandini of the University of Sao Paulo colleague of Dr Marcelo Dottori who will be the Chief Scientist running the recovery operation for 29, is on sabbatical here at Rutgers.  Brandini gave a fascinating talk highlighting his work at the University with ecosystems along the Brazilian shelf break that our team was eager to attend.  One topic discussed was the immense fishing that takes place along the South Brazil Bight- the northern portion being where the recovery is being planned.  After the talk he met with our team where he was able to point out where the main shipping lanes were and helped us plan our approach.

april19

In the image above we can see the result of the meeting being the red line which leads from Challenger's latest location south along the shelf and then crosses the shelf perpendicularly and makes a B-line in to port.  At the University of Sao Paulo, they have a budding glider program that will soon be monitoring the coastal waters of their region.

In cooperation with their program, Brandini and our team planned the location of that B-Line to be the foundation of a future long term survey to be run by gliders- similar to the Endurance Line that we have run off of New Jersey for over a decade.  If all goes according to plan. Challenger's final approach into Ubatuba will be the first of many glider runs along that line.

As for the conditions forecasted around our glider now, At the surface both models are showing evidence of a cold eddy to our south and warm eddy to the north creating the strong flux at the surface that is confirmed by the surface drift seen by the glider.  Subsurface however, RTOFS shows that there is movement northward in the water column that MyOcean doesnt pick up .  This push north seems to hold true when compared to the depth average current calculated by the glider showing an overall northward resistance.

Force Wind Sea & Honor

 

Crossing the EEZ

Saturday, April 12th, 2014

They Shoot! ... and they miss.

eez

We can't win them all, but the important thing is that Challenger has officially crossed the Southern Atlantic, the first complete crossing of an ocean basin in nearly 5 years!

approaching_ubatuba

 

Looking ahead, we are planning on flying a path roughly 750 km towards the port at Ubatuba. As of right now we are not sure what sort of boat will be available to us for recovery, so we will do our best to take care of our team taking part in the operations being led by members of the University of Sao Paulo, and get the glider as close as possible.  This way we aren't waisting precious time on deck and will have more time in the lab assessing the condition of the glider and being able to make the necessary repairs for the following deployment.  For now, the plan is to still travel down to Brazil in mid may for the recovery and redeployment so we shall keep our fingers crossed as we navigate the final stretch into port and move the necessary equipment to our friends in the southern hemisphere.

Force Wind Sea & Honor

Aiming for the Trifecta

Tuesday, April 8th, 2014

According to the currents being calculated by the glider, 29 has been seeing a consistent push northward throughout the water column.  This overall flux shows the currents at depth are strong to the north, redirecting our trajectory as we power forward towards shore. This flux we believe may be part of the Antarctic deep water that Antonio described during Silbo's crossing from the Canaries to the Caribbean.  The presence of this water mass moving to the north is what we believe to be the reason why Silbo was unable to follow the intended path across the equator and into the South Atlantic and instead had to divert to the west.

This resistance however is not too worrying this time around as flying perpendicular to it is allowing us to make consistent progress to the west.  Last night we shifted the way point a bit to the south as we aim for our next goal: The Trifecta.

apr08track

The Trifecta that we are shooting for is as follows:

1. Crossing of the Tropic Of Capricorn

2. Crossing of the Exclusive Economic Zone of Brazil

3. Leaving international waters concludes our crossing of the Southern Atlantic Ocean Basin

trifecta

 

As we define the end zone, we look to the US and European current forecasts to see if we can attain our goal...

Looking at the currents, MyOcean seems to match more closely to what Challenger is reporting as it shows the entirety of the water column weaving to the north-northwest while RTOFS shows the outer edge of the near by eddies resulting in a flux to the south.

 

Force Wind Sea & Honor

Returning to the West

Saturday, April 5th, 2014

As we leave the home base of our sampling scheme for the last time, we have thrown the way point out to the north west.  As we get closer to shore, there is a danger of being swept to the south by the Brazil current shown in the figure below:

 

 

 

 

 

 

 

 

 

 

We have also heard that this current meanders quite a bit, so depending on where we catch it, the strength of the southward flux may vary.

MyOcean's forecast today has a pretty cool looking eddy field within our vicinity. In the upper layers, there are two well defined eddies to our east and to the north west that can be seen through 300m.  Below that, the eddy to the east fizzles out while the one to the north west weakens with depth.  In the RTOFS model, the main feature of interest is the eddy to our West-Northwest that lies within the path we plan on flying towards the coast.  Depending on how fast this eddy moves we may be able to dissect it in the coming weeks.

 

Force Wind Sea & Honor

Criss-Crossing the Tropic

Tuesday, April 1st, 2014

Last night Challenger completed another mile stone as she crossed the Tropic of Cancer for the second time since being deployed- however she quickly jumped back to the north as she followed the path of our final wing of the eddy sampling mission.

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Over the next few days she will fly in towards the center of the fan for the last time before we throw the waypoint towards the shores of Brazil and begin making our final plans for recovery.

Looking above at the gallery for the currents today, there is a drastic contrast between what the models are forecasting.  MyOcean is showing an overall flux westward throughout the entire water column that aligns well with the deep eddy that has been moving steadily to the north.  On the other hand, RTOFS is showing an overall flux through all layers to the south east caused by the lower left rim of the warm core eddy at the base of our sampling scheme as it meets up with another eddy to our north- possibly the same eddy present in the MyOcean model.

 

Force Wind Sea & Honor