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Lagrangian Structure of the MAB

Over the past week, Silbo has been riding the northern edge of a warm core eddy as we make our way through an eddy solar system sitting on the edge of the Gulf Stream and continuing to make progress away from the Eastern Seaboard and further into the open ocean.


As seen in the image above, the trough of a large meander of the stream has been encompassed by warm eddies, creating an eddy solar system with a cold core eddy at its center. However now at the end of what the warm eddy was providing us, Silbo is now seeing a shift in the direction of the currents and so it is time to change the way point.


Antonio gave us a new way point to the south east that will be applied over the next day or so that will then get Silbo deeper into the Gulf Stream as we begin to see it dip back down to the south east.

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Entering the Gulf Stream

After over two weeks of unfavorable currents as Silbo fought its way across the shelf, this past weekend we struck gold by finally breaking into the gulf stream.

The Gulf Stream which moves on average at a speed of roughly 6.4km/hr picked up Silbo and launched him bringing the progress up from 10km/day to over 40!


Looking to the currents, both the Copernicus and ROTFS models show the strong serpentining current where Silbo is moving south west along its northern slope.

Copernicus 5/17

Copernicus 5/17

However, there is a discrepancy in the models where it appears an eddy has pinched off along the gulf stream.  In Copernicus, the eddy looks like it is more to the north of the glider and so wont pose much of a threat to our eastward progress while in RTOFS it appears more to our south meaning if Silbo continues along the current path we will see the currents swing around and push back towards the west

RTOFS 5/17

RTOFS 5/17

As we see the current continue to evolve over the next few days the discussion will continue on where we will take this glider on its North Atlantic Crossing.


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Silbo Update Friday 13th

After crossing the shelf and entering open water last week, Silbo managed to make steady progress eastward while feeling the effects of a consistent push to the west towards shore.  This westward current however cut Silbos speed in half from 30+ km a day  to ~15.  The model visualizations below show a representation of the area:


Copernicus Forecast May 13

In the Copernicus forecast, it appears that Silbo is in the midst of a filament breaking off of the northern wall of the gulf stream to become a small warm core eddy.  However the currents reported by Silbo say the flow is in the opposite direction as shown in the american models below.


Oscar Forecast May 12

In the Oscar output about and the ROTFS Forecast below, both visualizations are showing a cold core eddy breaking off of the large jet producing the westward current being reported by Silbo.


RTOFS Forecast May 13

In an attempt to break free of this current, Ben is issuing a new waypoint to the south that will help steer the glider free of the head current and into the Gulf Stream

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The Return of Silbo

After a two and a half year hiatus, Silbo, the first glider of the Challenger Glider Mission is back in the water!

Deployed at noon on April 13 2016 right off of Cape Cod Massachusetts , the glider spent roughly a week flying a low angle thruster mission through the shallow waters of the Georges Basin along the shelf.  Then Silbo made its way along the Fundian Valley before entering the deep water of the North Atlantic on the evening of April 26th.


Now off of the shelf and heading East, the team is discussing the end point for the mission.  The overall goal is to complete another crossing of the North Atlantic, however where we want to set the finish line is still up in the air.  In 2009 the Scarlet Knight, a 200m glider crossed from New Jersey to Northern Spain.

The potential plans as proposed by Ben Allsup (TWR) are as follows:

Scenario 1: Falmouth, United Kingdom – 4400km in deep water, 320km along the shelf.  This scenario would be interesting as Silbo was deployed from the town of Falmouth Massachusetts and would be nice to connect the two cities.

Scenario 2: Galway , Ireland – 4300km deep water, 100 km on the shelf.  This choice would include a partnership with our friends at the Marine Institute in Galway.

Scenario 3: Canaries – 4500km deep water, 10km on shelf. This brings Silbo back to where he made land fall in the summer of 2012 after deployment from Iceland and reunites him with Antonio at ULPGC and the friends at PLOCAN.

Scenario 4: West Coast of Norway – 5512km deep water, 80km shelf and shallow area around the Faroe Islands.  This would be the most difficult path and is mot unlikely.

Scenario 5: Iceland – 4200km deep 85km along shelf.  This route returns Silbo from his initial deployment location from June 2011, however the consensus seems to be that Iceland doesnt feel far enough across the ocean for it to be a full crossing.

Scenario 6: Mallorca – 5700km deep, 50km on shelf.  This is the pie in the sky route which involves the very tricky passage through the Straight of Gibraltar.

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Pictures from the recovery

Flags of the Four main nations that participated in the recovery

Flags of the Four main nations that participated in the recovery

RU29 in the Zodiac

RU29 in the Zodiac

RU29 on the Algoa

RU29 on the Algoa

Freshman Undergraduate Student Cassidy describes the recovery to fellow Rutgers students

Freshman Undergraduate Student Cassidy describes the recovery to fellow Rutgers students

The Bear is in the Igloo

On March 31 2016, RU29, Challenger was recovered by a team of scientists and students off the coast of South Africa, completing the circumnavigation of the South Atlantic.  When the team arrives back on land tomorrow afternoon, we will get more details on the recovery.


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Setting Sail


Early this morning, Antonio sent over this picture of the boat as the team was moving the equipment on board and preparing to set sail.


The glider is currently 230 nautical miles from Cape Town, so the team will have about a full days steam to get on location.  If all goes well, early tomorrow they will be on location and preparing for recovery.  After 282 days at sea, its time to get this glider out of the water

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The Team Arrives in Cape Town

After spending the weekend following Antonio’s waypoint, our luck continued to get better as the currents continued to shift in our favor rotating from West to North North-East.

1 km per hour

With this favorable current, 29 managed to get back up to speeds of 1km/hr vs the 1km/10 hrs progress we were making last week.

By Monday however, the current continued to rotate around – the result of how hectic the landscape is of quickly moving eddies through the area.  Even with the 180˚ change in current direction, the glider continues to make good progress in the direction of Cape Town.

With the latest forecasts, the British GLOSEA is the closest to what the glider is reporting, showing a medium sized warm eddy to the south of 29 resulting in the currents shifting back to the west.



Since recovery is quickly approaching, we have shortened 29s flight pattern to 4 yos and turned the ctd on for both up and down casts so we can gather a nice data set upon approach for data comparison with the recovery vessels on board ctd.

Finally looking at the AIS data in google earth, the RV Algoa is waiting at the port for this weeks activities


Over the past day, the team has been arriving in Cape Town and this afternoon will be meeting at the Algoa to load up some equipment and discuss the plan for recovery.   Then, weather permitting, the team will set sail early tomorrow with the intent of arriving at the glider early Thursday where they will get the glider out of the water after 282 days at sea and 6700 km.

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T minus 6 days

Now less than a week away from when the team will arrive in Cape Town and set sail to recover Ru29, we continue to fight the oceans currents as we look for the best way to get the glider closer to shore.

On Tuesday, 29 was given a new way point and almost immediately we saw a change in the direction of the currents as they rotated from West to North-West, and as the week continued this rotation moved further and further north.

Screen Shot 2016-03-22 at 7.54.49 AM (1)

A reduction in the number of yo’s per segment also led to a decreased number of oddities from the pump.  As of last week, the pump was holding steady at 32 oddities; we reduced the yos by 25%, so we would expect the oddities to then drop to 24.  However the result was 19, so 19/24= .79 so they effectively dropped by 21%.  The more well behaved pump has also lead to the power usage dropping back down a bit allowing the team to rest a little more easily.

By Wednesday, the persistant West North-West current had slowed Challenger down to a crawl of about 1 km/10hrs while the glider continued to try and push east to the cold core eddy.  It seemed though that the warm eddy in the image above had shifted and the northern edge was what was causing the strong westward current.

Antonio however suggested we move the waypoint to the North East of the glider citing the Copernicus salinity data overlayed with the current fields.  The water that spills over from the Indian ocean into the South Atlantic is significantly more salty and shows up very nicely in the data:

Copernicus Depth Average Current with 260m Depth Salinity

Copernicus Depth Average Current with 260m Depth Salinity

With the new waypoint set to 32º30`S, 14º30`E, Challenger regained some pep in her step as the currents rotated further to the north and she covered a significant distance compared to the progress made over the past few days


With this change of luck we will keep Antonio’s way point and see if we can continue to make better progress while the recovery team makes final preparations for their travel to Cape Town

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March 21st Update

Screen Shot 2016-03-21 at 8.06.22 AM

The image above shows that RU29 is about 95 kilometers from South African waters. However, the currents are the wrong direction flowing more west than anything else. And it is hard to rely on what the glider is reporting.  The waypoint is northeast, the reported currents are mostly west, even when you account for the persistent difference in magnetic versus true. Yet the glider is traveling slowly southeast.  The following are todays forecast products

Oscar Mar 21

Oscar Mar 21

OSCAR says if we can just get a bit more east, we will begin to feel that large cold core eddy that will bring us around clockwise into South African waters.  That means we should soon see currents to the north. Dave’s suggestion of flying ESE will aid in getting us there.



GLOSEA agrees with the OSCAR forecast, also showing the large cold eddy to the south east.

HYCOM Mar 21

HYCOM Mar 21

HYCOM says we should have had a favorable current to SE that last few days, and we did not. It also says if we fly south, we will enter a current to the west. But we are already in a current to the west – our present issue. HYCOM further says that if we continue east, we will find ourselves in a strong southward current, the exact opposite of OSCAR.

RTOFS Mar 21

RTOFS Mar 21

RTOFS is showing the same as HYCOM but with slower currents. ROTFS does however start with the same initialization as HYCOM, but uses different winds to complete the forecast.

So we have two products saying we should go ESE, and two products saying there lies danger. The Copernicus product however is not yet available for a tie breaker on the guidance side as they are in the process of doing maintenance on their site.

Despite what the models are saying, Challegner is telling us East North-East is not working, and that straight East will not work.  29’s track is telling us to try ESE to see where it gets us regardless of the guidance.  Hopefully the model guidance from OSCAR and British are more correct.

For the gliders status, the power plots have to be adjusted.  We are up to about 3.2 AH/day, and down to about 50 days left.  That is end of April/early May if nothing else happens, like the need for shallower dives or more pump leaks.  Luckily we are all set to recover in just over a weeks time.

Communications and steering are holding steady, but the oddities and pump issues on climbs outlined last week are still the main problem and the source of the increased power draw.  At some point this week we would like to try and pull more data from the glider to see if there is anything that can be done, however that would require a more prolonged surface time and at the moment we are in a pretty high trafficked area


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