The Challenger Glider Mission

Page 31 of 37

¡Bem-vindo aos Açores!

October 26, 2011 /

Hey All!

In just a few hours now, the last of our team will be landing on the beautiful island of Terceira and conducting final preparations before leaving dock at 10:30am (6:30am EST) and will spend the day sailing out to the glider.  Unfortunately as of right now, Challenger is still just under 90 km from the port of Praia da Vitoria, but by the time they leave it will be closer to 70 km away.

While on the trek out to the glider, the ship will also deploy two new buoys to collect data while drifting with the currents, so it will be a long day for everyone.

We will keep everyone posted on the progression of the inspection

Force Wind Sea & Honor

Nilsen & Antonio

Conflicting Currents

October 25, 2011 /

Hey All!

Challenger is continuing to chug along as it gets closer to the Azores.  By morning, this brave glider will have acomplished yet another incredible feet, flying over 3000km since deployment just 124 days ago!  After moving the way point to the west late last week, Challenger continued past the Sedlo Seamounts, and is now on his way back east towards Terceira.

Challenger is now also less than 130 km from the tropical shores of the Azores.  Wednesday the 26, a team of scientists from the Canary Islands, the Azores, and from Teledyne Webb will set sail from the port of Praia da Vitoria and meet up with the glider.  There, it will be inspected to see if there is any significant biological growth on the exterior.  There will also be a number of files pulled off the hard drive to make more room for the final portion of the journey to the Canary Islands.

ULPGC Sea Surface Height & Currents

HYCOM Sea Surface Heights & Currents

As we close in on our rendezvous location, there is a little discrepancy between the models forecasting what the conditions are like.  The first figure shows the ULPGC data showing strong currents that flow right towards our way point off the eastern coast of Terceira.  The second figure is from HYCOM, showing quite a mess on the road ahead.  As of right now, Challenger has been seeing a correlation shown by the ULPGC data, and if this holds true by Wednesday morning we should be within 80km of the port.

Finally, our friends at ULPGC provided us with a weather forecast for the date we plan on being out on the boat.  On the 26, it looks like there will be waves reaching up to 3m with winds potentially reaching 25 knots.  This will cause the swells to have a period of about 9 seconds.

 

We’ll keep everyone posted on the inspection!

 

Nilsen & Antonio

Closing in on Sedlo

October 20, 2011 /

Hey All,

So Challenger is continuing to inch ever closer to the Azores (<250km) as we begin preparing for next weeks inspection off the coast of Terceira.  However this also means we are getting closer to the Sedlo Seamounts (<60km).

These seamounts as we had mentioned last week may reach up to nearly 500m from the surface, which poses a threat to our brave little droid.

To make it worse, three models of sea surface height with currents confirm there is a large warm eddy just to our west that could be strong enough to pull us right into range of the seamounts which would be detrimental to our flight.

ULPGC data for SSH and Currents

HYCOM SSH and Currents

Model from Antonio at ULPGC

Since late last week now, we have been flying with the current correction on try and keep us as close to the path to Terceira as possible so hopefully that will aid us in avoiding being dragged too far west towards the seamounts.  Also we may move the waypoint further east a bit to try and point us more away from the obstacle and towards the rendezvous point for late next week.  We have also moved the way point east to 25.5 to try and steer ourselves away.

 

As always Force Wind Sea & Honor

 

Nilsen, Antonio & Oliver

Making good progress… for now

October 12, 2011 /

Hey All!

So Challenger 1 is continuing on his way towards Terciera making great progress as the past three surfacings have each carried us over 10km.  This is due to the presence of currents finally moving to the south and aiding us instead of causing resistance.  In order to try and take the most advantage of these currents while they are helping us, we moved the way point further to the west to try and decrease the angle we were flying relative to currents to a minimum.

Sea Surface Height and Surface Currents from ULPGC

Looking at the data from University of Las Palmas Gran Canaria, at the surface the currents are moving to the North as we are on the western side of a cold eddy.  However, looking at the water’s velocity at depth, we are finding much more favorable currents.

Currents at 300m depth

By abiding by our new protocol of flying 25m-1000m instead of (0-1000m), we are not only avoiding potentially being struck by a boat, but also the upper 25m of those Northern Currents.

Unfortunately, it looks like we may not have these currents for much longer.

Since October 8th, it seems the currents have been following a large inertial oscillation where they have gone in a counter clock wise rotation from north 180˙ to the south where we were this morning, and now showing evidence that it is moving westward and potentially back to the north by Friday.  If this happens, we may run into yet another wall of currents.

This posses a problem energy wise, as our batteries continue to get drained at the same rate (or even greater) as when we cover a lot of ground.  After a little discussion of this, Lauren Cooney presented us with a plot showing that when we are flying into a head current (similar situation to what we saw last week) the estimated distance we have enough power to cover is cut down to about 2500km.  However looking at today with the currents behind us, our potential remaining distance is up to about 4000km.  So distance wise, it really comes down to how forgiving the currents will be to us.

Finally just checking out the energy plot made by our friend from PLOCAN, Ruben Marerro Gomez it is looking like we should have enough energy to sustain us through the beginning of February.

 

Now making an estimate of our path from our current location to just north of Terciera and over to the Canaries it looks like we should have enough energy to make it.  We are just about 1600km from our final destination and have used about 343 of our estimated 700 Amp-hr.

Check back for another update soon!

Nilsen Strandskov, Antonio Ramos, and Lauren Cooney

VIIIG Club and some other pretty awesome Achievments

October 11, 2011 /

Hey All!

Sorry for the gap in the updates but we bogged down a bit by a few nuances called exams.  But anyway here is a recap of what our brave little droid has done over the past week.

First off, Challenger 1 has now gone 2,600km in just over 109 days, making its mission the 3rd longest of the Rutgers Fleet!

He also has a great view to his East as by morning, he will be crossing the border from Norther Spain to be parallel with Portugal.

Finally, Challenger is just about 400km from the estimated rendezvous point just north of the island of Terciera where the watersare still close to 1000m deep so that we can continue flying efficiently.  Here, an ocular  inspection will take place so we can get an idea of how much biology has grown so we can see the effects of consistently diving deep.  The ship that will be used is from the Portuguese Navy and a picture is below:

Over the past week, there have been a number of brief way point changes that have occurred.  Trying to line the glider up to fly a path where we could pull off getting close to the Azores for the inspection turned out to be the equivalent of threading a needle.

Towards the end of last week (oct 8th), we had been flying into a bit of a head current that cut our speed down a bit.  To get out of this, we gradually moved our way point three times to try and get around to more advantageous waters

Although it was slow moving and a bit boring to try and fight these currents, our models produced some really great looking imagery for our road maps.  Below find the map of Sea Surface Temperature from ULPGC

As the weekend continued, by the 9th, the currents had shifted from going North, to North West, West and finally to our south west.  When we saw the currents follow this oscillation, we decided to move the way point from our east back to the west to try and take advantage of these currents.

With the movement of the way point, we began seeing good progress yet again, however the currents began shifting back up to the north again.  To avoid these, we decided to incorporate our new flight protocol of flying below these pesky currents.  We flew 3 segments with our inflection depth set to keep Challenger between the depths of 200m-1000m until it is time to surface.

Another change made by Lauren was to the minimum allowable speed.  She pointed out that there is some sort of temperature anomaly about about 900m where we see the temperature increase back to about 9˚C.  The change in speed will prevent the glider from trying to make any unneeded changes to accommodate the change in density onset by the increase in temperature (the temperature shift can be seen on the last plot in the figure below).

After making these changes, we continued to make good progress as we now follow our way point and the currents a little back to the west.

We have also returned out inflection point closer to the surface, but not all the way there..

After seeing these images (each dot represents a ship of some sort), our hearts started pounding a bit harder.  As we have discovered in the past, gliders do not fair well against ships, and it looks like we have gotten pretty close now to areas that have pretty frequent shipping traffic that we will have to dodge on our way to our rendezvous point.  So we have left the inflection depth at 25m hoping that will keep us safe from any detrimental surface currents or collisions with ships.

That is all for now and we will have more updates soon!

Oliver Ho, Antonio Ramos, & Nilsen Strandskov

 

A Hundred Days at Sea!

October 2, 2011 /

Hey everyone,

Our indomitable glider has finally breached the walls of the detrimental eddies that have been obstructing its path for the past week. As of October 2, Challenger 1 has been at sea for 100 days!

Challenger 1 is now less than 700km from the Azores; Terceira specifically. Off the coast of Terceira, members of our team will give our brave glider an ocular inspection. If all goes well, Challenger 1 will continue sailing Southeast towards the final stretch that is the Canary Islands.

Our little droid has been through quite an exciting week.  He has passed through a number of interesting sightseeing points and flown an obstacle course and is now back on his way due south to the island of Terciera.

First, as we navigated the wall of North bound currents towards the end of last week, we then began focusing on our strategy to get around the Lukin-Lebedev seamounts.  A seamount is a landmass that juts out of the seafloor for thousands of meters, but does not breach the surface.  So it is similar to an island except that it does not reach all the way up to the air.  Because these anomalies are in the middle of the vast abyssal plain, large migratory animals will use them as reference points on their excursions.  This also can be problematic as our glider, although tough, is no match for a collision with such things as a whale.  Thus the presence of these are detrimental to Challenger as if we were encounter any of these, it would mean an untimely end to this courageous mission.

One problem we found in navigating the seamounts was that in the different bathymetric models of the ocean floor, we found a number of different values for heights of the seamounts in our area.  As a safe guard to avoid any sort of collision with the raised sea floor, we decided against setting Challenger to dive to any specific depth and to instead turn the Altimeter on. This option basically uses a sonar that way the glider can tell where the sea floor is.  Although this technique is useful, it is also quite inefficient battery wise and so upon reaching a safe distance from the sea mounts where we were confident we would not get dragged back due to unfavorable currents or any inertial oscillations from the storms, we turned the altimeter back off and sent Challenger on his way.

Then we began focusing on future plans for the mission.  If necessary, we have organized for a Portuguese Naval vessel to be available to do a visual inspection as Challenger arrives at the Azores.  We believe that (based on current conditions) Challenger will arrive off the coast of Terciera by the last week in October.  As we approach, we will need to keep a vigilant eye on what the currents are doing, where the sea floor is, if/where the shipping traffic is, and where our escape routes are.  The last thing we need is for our mission to be ironically ended early as we try and see that there is no significant biological growth that may be a problem later in the mission.

One of the main topics of discussion we have had recently has been changing the parameters of our dives.  We have been looking into setting a specific range for Challenger to dive between that is more specific than 0-1000m.  The benefits we are looking for is to 1- aim for the most favorable currents in the water column and 2- avoid surface waters when we know of shipping traffic.

Navigational wise, we are planning on flying close to the 26W marker until we reach about 39 N.  Then we will hopefully encounter an eastward flow that we can ride parallel to Terciera for the visual inspection and continue past Sao Miguel before turning towards the end zone of the Canary Islands.

Also it is looking that we should not encounter much inertial oscillation this week as we should be largely unaffected by storms for the time being.  Both Hurricanes Ophelia and Tropical Storm Philippe look like the may miss us as Challenger is now further south than the Jet Stream is currently reaching.

Finally, Challenger now has some pretty fine scenery to both the left and right as he is now parallel with the eastern shores of Maine and the North West coast of Galicia, Spain.

 

Great work team! and as always

Force, Wind, Sea & Honor

Oliver Ho, Nilsen Strandskov, & Antonio Ramos

Storm after Storm

September 25, 2011 /

As we awake on this cloudy sunday morning, Challenger is in the midst of yet another storm.  But nothing in comparable magnitude to what is in store for Challenger in the upcoming weeks.

By the middle of next week it looks like the remnants of Tropical Storm Ophelia and Philippe will be reigning down on Challenger’s position.  The combination of these storms will undoubtedly cause some intense inertial oscillations for our little droid and it will be important to keep an eye on the intensity of these storms as they travel over the warmer waters of the North Atlantic.

The Jet Stream forecast even shows an intense meteorological oscillation to be in the vicinity for a week from today that may cause intense surface currents.

 

Nilsen & Antonio

Another brick in the wall….

September 24, 2011 /

Hey guys..

This week and the previous one have been really busy for Silbo and his team. The aftermath of Katia has not been exactly a blue paradise, sunglasses, a fresh drink and tons of pop corns.

THE WEATHER
The weather has improved and the slight storms reported have been crossing North Silbo. Silbo can now enjoy the stars brightning in the sky at night surfacings before calling home. There are no spetial mentions for the meteo the last week. However, waiting for the calcules of the heat fluxes, it looks that silbo has well reported that tropical storms definitely affect the water column at great depth. Changes on salinity and temperature fields at depth are obvious on vertical profiles.

Figure 1.- Temperature and salinity fields reported by Silbo (23th jun – 23th september).

Another important remark related the meteo, is that last swells affect, but it do not seem to –inertially- oscillate the currents like in the previous week… On Monday, we will have another perturbation coming from the west and the swell would slightly increase the significant height (Hs) of the waves following the forecast of the Spain,s system of marine weather forecasting.

Figure 2.- Marine wearther forecast 25 and 26 september 11.

THE WALL
However, as we posted some days ago, the toast of the week goes to an old and well-known feature.  We have another WALL ahead. It has been the great headache of this week. Our little and brave droid becomes another brick in this liquid wall by moments. The first result of finding a wall is that the glider stops and drifts to any resultant random direction. We found two of these particular glider obstacles during the RU27 mission: The first, was a system of two warm eddies gyring in front and behind scarlet. Currents headed the glider when we move East, and pushed to South when we come back. The other wall found by RU27 was a great inertial oscillation changing the current direction 360 º around scarlet each 16 hours…during some weeks…http://www.i-cool.org/?p=6944

This particular liquid WALL found by silbo some days ago, is clearly associated to the western side of a warm (Sun) eddy that has stopped (literally) to our brave droid. We are crossing by the Western (bad) side with counter currents flowing at >0.3 m/s and strong SSHa gradients up to 3 cm/nm. He cannot fight with the strong currents flowing direct to his nose and his flying line. We have suffered some stints with Northern moderate drifting.

Figure 3.- Surfacings of 21th of September 2011.

OPTIONS
The question: How to cross it ?
We tried to convert our great Silbo in a 4*4 (strong), but fast (>0.3 m/s) glider to fight the current.

1.- The first option that we tried, changing our WP to 27 W (180 degrees with the current direction). Our aim was to head the wall and try to cross it increasing his speed and changing his navigation schedule. On 27 W we identified a jet stream flowing south. We want to get this good opportunity to get south currents for a while. But it didn’t work. Silbo can hardly advance only a few km/day…

Figure 4.- Current field (down) and N-S meridional component (up).

2.- We also changed to full buoyancy mode since we were drifting to back. During some stints with similar currents and diving periods, we got some interesting numbers. We increased our glide speed from 0.24 to 0.31. And we run a 5 % more of distance by stint: without (4.28km) and with (4,61km) full buoyancy.

Figure 5.- Surfacing reports at half and full buoyancy modes. 22th and 23th of September 2011.

3.- Other options discussed and finally do not executed by different reasons (energy consumption..). Increasing the pitch (better diving speed but shorter distance run) and switching on the Current Corrector.
However, sometimes during this meridional (N-S) mission, we have been forced by the circumstances to give and step back, and see the problem with a little bit more of perspective. We could hardly advanced only some more km/day with this new schedule. Thus, we decided to completely change our GLOBAL strategy. If you can cross the wall, surround it…

Figure 6.- SSHa field. 21th september 2011.

Thus, we changed the WP to the East (22 W), < 180 º related to current direction. As a result, since thursday, we have been drifting to SE-E for some stints. We are still suffering the effect of this great wall (strong NE current). Our target was/is to pass it flying to the centre of the eddy, and then, flowing to the SW again with the South oriented current of the other right side of this warm eddy. We would also avoid the seamounts located around the 44.5 N 25 W. Then, free riding to our little cowboy until the Azores. A visual inspection at sea is projected to be held there.

Figure 7.- Current field. 21th september 2011.

 

If you can cross the wall, you can surround it…But you can also pass UNDER THE WALL..That is another idea floating in the core group: Changing the flying depth range of silbo. This operation would be especially useful when silbo crosses bad strong upper currents. Diving and climbing at deeper waters like thermal gliders do (for ex Cook, 300-1000 m) would be an interesting option since current fields (soft some areas) would be of moderate currents when compare with these flowing in upper layers.

The core group is working right now on some simulations and technical issues and how we use the layered data of the ocean (NLOM, HYCOM, MyOcean) and how to take advantage for our purposes.  We would update it ….

Finally, just a little reference to the toast of the team this week:  Lauren COONEY from TWR. She has done an incredible great job the last days …

Force, wind, sea and honor all

Antonio RAMOS, Nilsen STRANDSKOV and Lauren COONEY

 

Drastic Times Call for Drastic Measures

September 22, 2011 /

Hey all,

Well we still seem to be caught in the strong northerly currents I spoke of last nigh which have now over powered Challenger and have started pushing him to the North East.

 

To try and combat these currents, we moved the way point a bit further east and set the buoyancy drive to full.  Hopefully this will give us enough kick to try and break free of these strong currents and begin making progress to the south when we reach the edge of this eddy.

Nilsen & Antonio

Aquarius: first images

September 22, 2011 /

Hey guys just wanted to draw everyone’s attention to the brilliant scientists at NASA who just released the first global Sea Surface Salinity map produced by their new satellite Aquarius!

See the url below for the full article.

http://www.nasa.gov/mission_pages/aquarius/multimedia/gallery/pia14786.html

 

Nilsen

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