Category: Challenger Mission (Page 23 of 37)

Hey All!

So today our team bounced some ideas around to see if we could find a solution to Silbo’s predicament.  For the past few months, Silbo has been faced with a strong current ranging from North North-West to North North-East that has slowed us to half of the speed we have flown in the past.  One idea that we had stemmed from an event that happened last week, when Silbo had an error that caused him to only dive to 600m.  When he surfaced he reported that the currents were closer to what the model is telling us: flow to the south west!  So the initial idea thrown around was only having Silbo dive 500m, however this would cause the pump to move twice as often, bleeding the battery.  Another option suggested by Ben from TWR, is to have Silbo dive to a depth we feel would have favorable currents, and maintain that depth and have that favorable current push us for a few hours.

Antonio and I suggested that if we try this ‘hover’ strategy, we should try for 200m.  It seems that the currents  towards the surface may be closer to what the models are telling us, so we chose a depth that wouldn’t take us too far into the unfavorable current.  Another aspect to take into account is that we want to stay out of the productive surface waters.  From our experience and the word of others, the rule of thumb seems to be that barnacles stick to waters >15˚C.  As seen in the temperature time series above from Silbo, 200m keeps us in waters that are roughly 12˚C.  We may not get to this test tomorrow, but I will update you guys on our progress over the weekend.

Down south, Challenger continues to shoot through South African waters on her way towards open ocean.

Tomorrow, we may move the way point more to the north to take better advantage of this northward current we are seeing and ride it out for a few years.  It seems the counter clock wise spinning eddy is slowly moving off shore, so we are trying to bring Challenger towards the outer edge to avoid the possibility of being dragged south when we reach the other side of the eddy.

Force Wind Sea & Honor

Hey All,

I just wanted to leave everyone with a quick update before the end of the night.

In the North Atlantic, Silbo is still muscling his way through the northward flux as we brainstorm ideas to find a more favorable route to take.

Tomorrow, we may make the way point change I had mentioned

Although it looks like there is a clear path for us to take based off of the model, this overlay is only of the surface and tomorrow I will focus on getting subsurface currents to see if that picture gets any better.  This subsurface northward flux has plagued Silbo now for months and we really need to figure a way out.  One glimmer of hope was during an oddity that Silbo encountered late last week.  Silbo’s mission file reset mid segment resulting in a short dive that prevented Silbo from going the full 1000m.  On the short dive, Silbo recorded currents that were in fact flowing in the general direction of what the model was showing, providing us with the theory that the subsurface currents are what is slowing Silbo’s progress.

If we can pin point where these negative currents are, we may be able to adjust the depth Silbo is flying to to try and make some more favorable progress.  This however will cause a trade off with power consumption as we will move the pump more by making shallower inflections so we will have to weight the consequences when there is enough evidence to make a decision.

On the other hand, in the South Atlantic Challenger is still making good progress as she flies towards international waters.

Challenger is now 175 km away from international waters.  Once there and free of the danger of interfering with another countries boundaries, we will expand our view and find the most ideal path onward towards Brazil.

The way point given towards the end of last week is still proving its worth as it now allowing us to fly along the top of this warm eddy that will essentially carry us out of South African waters.

This is also seen in the maps from GeoEye and SeaStar that Antonio has gotten for us that show the warm eddy is similar proximity to the glider, providing that current to the north west that will carry us out to sea.

Over the past couple days, Dave has also been doing some fine tuning to Challenger’s flight parameters.  For example, we have been adjusting the cc’s on the pump throw to make adjustments to our dive and climb angles, changing the gains on the steering parameters, and testing out the low power mode.  The last one here is key as we will need to conserve power if we want to make it all the way across the Atlantic Basin on these batteries.  She has impressed us so far, but she still has a long road ahead.

Force Wind Sea & Honor

Hey All!

As Challenger makes more progress away from the shelf break and towards international boards, we cant help but be proud of how well she is flying.  After brushing the cobwebs off of our knowledge of geometry, we found that Challenger has been hitting speeds of up to 40 cm/s horizontal velocity- nearly twice the speed of what we have had with the older G1 gliders!

We are also collecting some beautiful data as we delve into the depths of the South Atlantic.  Above, is a time series of temperature since deployment recorded by Challenger, and aside from some false hits telling us the depth, the data set looks amazing.

As for the way point that was given to her last week, it looks like it is working perfectly.

With the way point set at the northern edge of the warm core eddy, we are getting dragged up and around the counter clockwise circulation, keeping us from being pulled into the center of the eddy.

We are very pleased to see that the eddy field we are edging ourselves into seems to be accurately depicted by both GeoEye/SeaStar and the RTOFS model.

Both agree with the positions of the counterclockwise spinning warm/clockwise cold eddies in our immediate vicinity and although the intensities differ, they show similar patterns of eddies further out to see.  Both also show similar positions for the warm eddies outlined in the 3d GeoEye/SeaStar image, which we hope will provide us with the path of jumping from warm eddy to warm eddy that will lead us out of South African waters and to the North West once we are out into the open ocean.

As for Silbo in the North, we are still plugging away trying to fight our way through this strong under current.  It looks like we may have a chance ahead as I am proposing a new way point to our team.

Hopefully if we can turn Silbo to the South at some point over the next couple days, we may be able to catch the signature of the small cold eddy to our south west allowing us to cut back to get good position on the large warm eddy south of that point.

Soon Silbo will be encountering the equatorial currents and we need to make sure we can gain good position before that point so we dont get swept up the northern shores of Brazil.

Force Wind Sea & Honor!

Hey All!

I just wanted to leave everyone with a quick update on our global gliders and their progress for the weekend.

Silbo is still fighting his away along through the middle of the North Atlantic, suffering from the continuous North-East flux we have seen for a while now.

However, yesterday we gave him a new way point to the west to try and see if we can find these western currents that we have been seeing in the models.  During the way point change we also saw something of interest, as Silbo did a single yo down to only a few hundred meters, and when he surfaced, he reported currents running in a similar direction to what the models have been reporting.  This means that subsurface there seems to be a large Northern flux that cancels out what we see on the surface and has been impeding Silbo’s progress.  Soon I hope to be able to plot up subsurface currents to see if we can get a clearer picture of what is going on.  From there we may be able to see more favorable routes that will get us out of this head current once and for all!

Down in the South Atlantic, Challenger is making her way off the shelf and into deeper waters, allowing her to now dive to the full 1000m potential of the deep pump.

As we make our way out into the deep water, we have been making adjustments to various parameters as we prepare for the long flight ahead.  For the moment, we are only collecting data on the first yo of each dive collecting at a rate of once every 12 seconds resulting in roughly 1.5 m resolution in our data.

As for the new way point Dave gave to Challenger over the past couple days, it looks like it may work very nicely as we have started to head into the outer reaches of the warm core eddy to our south west.  If we play our cards right, Challenger will hopefully continue to stay towards the edge of this eddy and fly more west than south as we head towards international waters, but we will update tomorrow afternoon.

Force Wind Sea & Honor!

Hey all!

So far this week, both Antonio and I have finally had some success with expanding of our piloting resources- however Antonio is a little further ahead than I have gotten.

This week, we set out to try and gather as many tools as possible to help our brave little gliders on the journeys that lie ahead. For Silbo: Continuing on the over 180 mission he has had thus far to the end zone of Rio De Janeiro.  For Challenger, the northern shores of Brazil.

After some discussion, Antonio was able to gain access to data from GeoEye and SeaStar to create some truly amazing imagery.

First off, Antonio has told us that the shores off of Cape Town are a very busy realm for primary production.

To get an idea of the levels of biology that Challenger is swimming through, Antonio was able to make a 3-D relativity plot.  In the image above, the higher elevation associated with the darker green color is the highly concentrated levels of plankton in the water, drawn to the area by elevated levels of nutrients from upwelling.  However, further off shore their resources are depleted causing the levels of primary production to drop off.

The blooms are so dense, that when we then overlay the current vectors over the map, we can see eddies outlined by the biology

Below is a further zoomed in picture to get a better idea:

In the currents (and plankton), we can see that there is a counter clockwise spinning eddy to our north west, and a clockwise eddy to our south east resulting in the currents aimed North-East towards shore.

These eddies are seen even clearer when analyzing with the Sea Surface Height maps.

Here, we can see that Challenger has set herself up right between a cold and two warm eddies, resulting in a jet that we hope will carry her out west and into international waters without unintentionally entering another countries waters.  As Antonio has put it, She is playing jump rope with the eddies similar to a game of double dutch!

I on the other hand, am still working towards being able to plot up the NCEP RTOFS model of the North Atlantic for Silbo.  So far with the help of John Kerfoot, I have been able to plot images of SST, first of the North Atlantic, and then of a zoomed in region that Silbo is currently flying in:

Not nearly as impressive as Antonio’s work but I will get there soon as we continue to push towards advancing our tools to safely pilot these global class gliders on their trans basin voyages.

Force Wind Sea & Honor!

Hey All!

While I wrestle with learning the ins and outs of new data sets, our global gliders continue to push onward in the Atlantic.

In a conversation today with Antonio, an interesting topic arose.  We have been brain storming for a while an anomaly in the salinity time series Silbo has been piecing together since deployment off of Gran Canaria.

The waters close to the surface and at depth have become relatively fresh compared to the beginning of the mission.  The waters at depth we recognized as Antarctic Intermediate Water which we have mentioned previously to be part of a subsurface circulation of the Atlantic.  However, Antonio brought up an interesting solution for the fresh waters we have encountered at the surface: Amazon River Outflow.  Apparently, in the past there has been evidence of fresh water flow from the largest drainage basin in the world reaching out across the Atlantic.  This, we think is a question we can answer as we get better at processing ocean models to compare with Silbo’s growing data set.

As for the endlessly persistent head current we have seen for months now, it looks like Silbo is now muscling his way between the western side of a cold eddy combined with the eastern side of a warm eddy- resulting in a strong flux to the north:

Depending on how this current evolves over the upcoming days, we may need to shift the way point to try and run with the cold eddy to our south east.  From there we will try and snake our way through the eddy field with the gyration of the eddies.

As for Challenger down in the South Atlantic, she is preparing to make the final leap into deep water, allowing her to fly to the full potential of our deep pump.  According to the position of the last call in, Challenger is flying in roughly 850 km.

Looking at the surface currents from the myocean forecast, we see an inconsistency between the model and what the glider is recording as the depth average currents.

This could be for a number of reasons, from low resolution of the model (I may be able to resolve this later in the week), the fact that we are crossing a canyon that may have a strong towards shore flux, or that 29 is flying along a thermal front that may produce a small scale eddy that again may not be resolved by the model.  Over the next couple of days, Antonio and I should be rolling out some new products that we hope will solve our resolution issues.  But we will have more on that tomorrow.

Force, Wind Sea & Honor

Hey All!

So over the rest of the weekend and through Monday, Challenger has continued to make progress towards deep water.

As we were continuing to fly across the coastal waters towards the open ocean, we were hit with a strong northward current that persistently pushed us every surfacing.  Dave made the call that we should try flying with the current correction option on, as to keep Challenger from flying too far north (remember, we don’t want to cause any international incidents by flying into another countries waters!). And so with current correction set to on, Challenger turned to the south in an attempt to compensate for the currents northward flux.

Since Sunday afternoon when this call was made, Challenger then continued to fight the current as we flew into the gradually sloping waters of the South African shelf break.  Now, Challenger is less than 14 km from where the gradual slope turns to a very steep cliff, with the sea floor dropping nearly 500 m over 5 km!

We have also seen an abrupt oscillation in the direction of the currents over the past 14 hours, from a strong Northern flow to a East-Southeast flow that has caused us to lose some velocity.  However, we have picked a new way point to carry us across the shelf into deep water over the next day.

The forecast for tomorrow from myocean (shown above) indicates that we may have another shift in current direction tomorrow as they rotate back into a favorable flux to carry us out into the open ocean.  Tomorrow, I will be processing more data to try and get a better idea of what form the currents will take.

As for Silbo, our brave droid is continuing to fly in the vast Atlantic.

Silbo continues to combat the strong North-East flux that has plagued him for months on end.  Over the past couple of days now, the currents shifted, but in a direction 180˚ to the direction Silbo was trying to fly.  So today Ben issued Silbo a new way point, way to the South, hoping to get a better angle on the aggravating current and try and make better progress.  This new way point is also very significant because it was placed below the equator and close to Brazil, giving Silbo a taste of the finish line of this next leg of the Challenger mission.  Tomorrow I will also process data for Silbo to try and see if his situation will ease up anytime in the near future.  But more on that tomorrow.

Force Wind Sea & Honor All!

Hey All!

So early this morning (2:24am EST), Challenger was deployed off of Cape Town, South Africa by a team consisting of Dave Aragon, JP, Ashley, Sinekhaya (Sea Technology Services) with Pieter Truter driving the boat while Tina ran the computer on shore.

They deployed Challenger just 10 miles from shore out of Cape Town where the water just about reaches 100m depth.  The water depth is important here, because Challenger is equipped with a deep pump, meaning the pump works most efficiently when flying in the full water column.  Being in shallow water with the deep engine, as we learned on the test mission this past summer, burns battery exponentially faster than flying in the deep.  So now we have moved the way point to aim Challenger for the open ocean where as the water deepens, we will run a few more tests before we send Challenger on her way.  As of this evening, Challenger is roughly 65 km from the shelf break, so we will continue to push onward.

We hope that as we cross the shelf into deeper waters, we can catch the northern edge of the counter clock wise rotating warm core eddy (remember being in the southern hemisphere reverses the direction of the eddies that we are used to in the north) and make our way out to the white line, indicating that we have left South African waters without unintentionally entering another countries designated area.

We hope to soon have pictures from the deployment to post here!

Back up in the North, Silbo is continuing to make progress across the great Atlantic Basin

Unfortunately, Silbo is still facing currents that are less than favorable…  Today, our little guy recorded currents flowing nearly 180˚ from the direction we are trying to fly.  Aside from this being bad news for Silbo progress wise, but it shows a disagreement with our ocean models, which are showing currents that would be very helpful, and not slowing us down to a progress of less than 6 km on the previous segment.

The angle of the currents Silbo has recorded over the past week has been rotating, so we can only hope that the the direction of the current continues to move as we continue to cross the series of eddies we have in our midst and we see more favorable currents in our near future.

Force, Wind, Sea and Honor to All!

The global Slocum Glider deployment map from yesterday:

And the same map from today:

The dot off South Africa represents a lot of work by partners at Teledyne Webb Research, U.S. Integrated Ocean Observing System, our new friends in Cape Town (CSIR, STS, UCT) and Rutgers.   Looking forward to the international collaborations that help that small dot grow into a new line across the South Atlantic.