Category: ru29 (Page 12 of 22)

Hey All

So we seem to have run into some trouble over the past day.  Challenger has had a sudden drop in voltage which we have come to find is associated with the lithium batteries being dangerously low on juice.

Challenger is now up at the surface drifting as we do not want to test how much remaining battery we have left.  We have been in contact with Collin out on the island to see if he is available for an emergency recovery.

Looking to PINZON’s forecast of the currents, it is dire that we get this glider out of the water soon, as it looks like the overall flow will be away from the island over the forecasted period, pushing us out of the recovery zone

We will keep you updated on the details of the recvoery, but for now here is some of the data we collected during our sampling missions.  It will be a much more complete data set once we recover and get the full files, but for now we can continue to see the oscillation up and down of the thermocline that we were hoping to capture.

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Hey All

Once again Challenger is making great time on her approach towards the recovery location.

Unfortunately, she may even be coming in too fast; so much so that Antonio and I have devised another sampling scheme to attempt over the next 10 or so days until our recovery team will be in place.  The plan we came up with is actually a relic from Silbo’s second mission, flying from the Azores to the Canaries back in the spring of 2012.

The plan we have come up with is to take Challenger and run a sampling mission through the eddy present within the lea of the island. As seen in the first image of this post, we will fly a “wind mill pattern” within the 35 nm recovery range over the course of the next week that will land us within 20 nm of the port we are to be recovered from by the first of November. From there, we will make slow progress towards the port by Nov 4th when we plan to finally get 29 out of the water, fix her up, and send her way ward back towards Brazil

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Hey All

Challenger has made it as far lateral as we wished to go!

Now we have placed her way point to the south east and will be making our final approach towards the island.  Although her progress was slowed by the currents running to the east-north east over the past week, she will still be arriving to the recovery zone well ahead of schedule. Antonio and I have been bouncing some ideas back and forth for ways to kill the next few weeks as we wait for Scott, Chip and Chuck to arrive on Ascension to recover and one of the most promising ideas may in fact be something out of the past. Check back in in a few days to see what we are cooking up!

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Hey All

As the recovery date looms nearer, Challenger continues to make head way parallel with the Ascension Fracture as we position ourselves for the final approach to the recovery location.  As previously discussed, Collin on Ascension Island told us that his boat which will be our vessel for recovery has a range of 40 nautical miles and that we should park ourselves to the west of the island within the lea.  From this information, I created the green polygon visible in the image above to set as our end zone as we prepare to wait out the arrival of our team that will be present for recovery.

Looking to pinzon, the sub surface current (>200m) continues to flow to the east, slowing us to roughly 22 km/day.  Even at these speeds, we should arrive within the recovery area well before our planned operation for Nov 4.  Until then, we shall continue forcing our way in the right direction as we come up with a constructive way to kill time until the recovery just under a month away

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Hey All,

So over the past week, we have continued to follow the sampling mission described last time: zig zagging our way over the portion of the Mid Atlantic Ridge called the Ascension Fracture as we make the final push to Ascension Island.

As predicted by Antonio, the currents have shown evidence of a rotation on either side of the ridge, clockwise to the south and counter to the north of the fracture

Another surprise we encountered while crossing over the rift was that on the first crossing, the glider reset underwater once again early on a weekend morning.  Unfortunately with these resets, we lose the data from the segment since it was written to the gliders RAM and not saved to the hard drive until the segment is complete.

Then later when we crossed the ridge again, we noticed that as we crossed, the compass began to spin close to when the glider should have been crossing over what is the thinnest part of the earths crust along the ridge, which may have caused a magnetic anomaly that led to the compass freaking out. A strong magnetic field we think could have caused the reset on the first crossing if it was strong enough

However on the third crossing, there doesn’t seem to be much of a reaction as the glider neither reset nor had too much of a wonky compass.

As the glider has been out for just under 9 months, the data on our pages has gotten very congested and so John Kerfoot has helped us out creating a new plot of the recent sampling mission, however, the data is a bit spread out for now so we can not make out any patterns just yet.  Looking at the old plot however, we can see the continued oscillation of the thermocline, although it has become much smaller than it was weeks ago.

Finally, as we are nearly ready to head west towards the island with a month still left before the planned recovery, Antonio and I have proposed to the group that we will fly the windmill pattern within the 40 mile box to the west of the island, which will keep us in range of the boat just in case anything bad happens.

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Hey all!

After this week, we are well underway into our sampling mission above the Ascension Fracture Zone.

With the sampling strategy we have laid out in the previous entry, we will be running a pretty close zig zag pattern over the ridge before running parallel to the north of the island.  With how tight the weaving pattern is, we have outlined the way points we will be pursuing over the upcoming days.

With how quickly we are making our way through this pattern, Antonio and I have been bouncing ideas off of each other just in case we have more time to kill. One idea we have arrived at includes flying a windmill pattern through a possibly eddy in the vicinity of the recovery zone

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Hey All

So since Antonio’s video call last week with the Ocean Observatories class, we have made the decision to sample the Ascension Rift over the upcoming weeks as our team prepares for recovery in the first weeks of November.

Back in April as Silbo crossed the Mid-Atlantic Ridge, Antonio discovered that there was a noticeable counter clockwise oscillation in the depth average currents.  These seem to be localized features caused by the flow of the gyre across the subsurface mountain range.

The plan we arrived upon for Challenger’s last ditch science mission will follow the path outlined below

The path runs us about 550 km from our latest location, which should take up roughly  23 days before we arrive near the western shore of Ascension island.  In preparation for this test, we have bumped up the sampling on the glider, now collecting data on all dives and climbs instead of on the first dive of each segment as we have done previously as a power saving technique.  But now as we have plenty of battery for what we have left to do before recovery, we will take advantage of the opportunity we have been given.  Within the next 6 surfacings, we should be just about ready to change the way point towards the west to make our first crossing of the fracture zone.

As we approach the ridge, Challenger has also come across a sub surface eddy that we have have traversed over the past couple days.

As seen in the depth average current calculated by the glider, we can see a clear rotation of the current following the pattern that could be associated with a warm counter clockwise rotating eddy.

A third oscillation we have noticed, is the depth of the thermocline.

Since the siesta back in May, the thermocline has been moving up and down in roughly two week periods overlaid with 3 day oscillations.  We are bouncing some ideas around with what could be causing this, but with the increased sampling rate, we may even be able to detect smaller scale shifts.

We will keep everyone updated on our project as it develops and we come to any conclusions

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Hey All,

Challenger is making quick work of this last stretch before recovery on the shores of Ascension Island.

With less than 260 km remaining between our brave little glider and the end zone, we could potentially make it to shore within 10 days with our average speed being around 26 km/day.   However, we do have some battery left and the potential to do some creative sampling around this little oasis in the middle of the Southern Atlantic.

This will be a topic of discussion in class today, but so far Antonio has proposed two branches of ideas: to circumnavigate the island to study the wake created by the island being in the path of the flow of the gyre, or ahead of us is a region called the Ascension Fracture which is part of the Mid-Atlantic Ridge- the topic of study here would be to look into the oscillations we saw with Silbo crossing the Mid-Atlantic Ridge some months ago in the north.

And the third option which could also be incredibly valuable to our cause would be hiring someone to go out and recover for us sooner rather than later- when Scott and Chip arrive in Ascension there will be a number of tasks to get done on a very limited time frame and if there is less than ideal weather, that could make things much more difficult. However, if we were to recover now that gives us a much larger window to find out what needs to be fixed on the glider, what needs to be in Ascension for the operation to be successful, and more time to get the glider in the water just in case the weather is stormy upon our teams arrival.

We will update later today on what is discussed during class

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It may be a slight exaggeration, but Challenger has picked up her game in the final hour of her mission.

Over the past week, our team has worked very hard meeting deadlines to get all of the necessary equipment for recovery and redeployment slated for arrival in Ascension Island in november. However, Challenger has kicked it into high gear, reaching speeds close to 25 km/day once more.  If this continues, we should be very close to shore within the next two weeks!  Yesterday, as Antonio predicted over 10 days ago, she crossed into the EEZ officially leaving international waters for the last time while on this mission.

Looking at Antonio’s 3-D bathymetry, the Ascension Fracture Zone is all that lies between Challenger and her finish line.  We plan on taking evasive maneuvers around this area even though our maps say it doesn’t rise further than 1600m from the surface just in case the maps are not in a high enough resolution to pick out small points that may be hazardous, and because we have loads of time to kill.

Once we get to the island, we plan to kill time in one way or another.  This will be discussed in class amongst the undergraduate students next week on Tuesday

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Fish & Chips and Roast Beef for all!

Just 350 km from the shores of Ascension, we should be in range for a recovery within the month!

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