Archive for September, 2009

6 Months at Sea

Sunday, September 27th, 2009

Today is September 27.  When The Scarlet Knight surfaces later today at noon, Scarlet will have spent a full 6 months at sea. Over the last 6-months, she surfaced 4 times a day, 3 times for navigational purposes and once a day to tansmit data for the dedicated science mission. Scarlet has so far flown a path length of 6,250 km, breaking the world record set by RU17 last year at 5,700 km.  She is about 1,111 km from our target point in the center of the CODAR HF Radar coverage off the northwest coast of Spain near Galicia.

http://www.puertos.es/en/oceanografia_y_meteorologia/redes_de_medida/index.html

This puts her at about the 80% mark, with about 55% of the power remaining based on our theoretical estimates of battery life.

090927_ru27_na_sst

Zooming into the present location, Scarlet is about to leave the Portuguese EEZ (thin white curve) and head back out into international waters.  Distance to the Spanish and Portuguese EEZs associated with the mainland ranges from 325 to 350 km.  The new altimeter data shown below has significant evolution in the area between 22 W and 19 W.  A new eddy is spinning up near 20 W that is straight to our east.  This makes the crossing through the trouble spot identified last week much easier.

090927_ru27_alt_1

Overlaying the satellite Sea Surface Temperature on the altimeter's currents, the agreement is excellent.  Warm water is moving north, cold is moving south.  The roadmap is good and we have found favorable currents.  Progress has been excellent the last day.  Scarlet's distance over the ground exceeded 45 km in the last 24 hours by combining her own velocity with a favorable tail current.  A good way for her to celebrate her 6 months at sea.

090927_ru27_alt_sst_1

The time estimate

Saturday, September 26th, 2009

An important question keeps coming up for planning purposes.  If we do make it across, when will we get there?

Mike Smith, one of the undergrads in our Atlantic Crossing class, has been working with us on the MACOORA Mid-Atlantic CODAR network for over a year. CODAR is a shore-based radar system for mapping surface currents. Following in Evan's footsteps from last year's summer internship at Puertos in Madrid, Mike's team is now working with the Spanish CODAR system off Galicia on the northwestern coast of Spain.  Our target is the center of this CODAR current field, which is just offshore the European shipping lanes. If we make it this far, it is very likely that we will have to loiter offshore for a few days waiting for a weather window that allows a pickup vessel to get out.  CODAR provides the best real-time current maps that we then use to station keep.  Its what our Coast Guard uses to save lives in the Mid Atlantic.  And its exactly what we did at the start of the mission, using the real-time CODAR surface currents to pick a route across the busy New Jersey shelf. 

galicia

Zooming out to the open ocean, we switch to the satellite based altimetric radar system to get surface current maps. The straight (yellow) line distance from The Scarlet Knight to the center of the target CODAR field is now about 1150 km.  But thats not how gliders fly.  If we follow the currents from the satellite-based radars, we get a line that looks more like the white curve.  That white line is just under 1400 km long.  Assuming the typical 20 km per day speed for a clean glider, thats 70 days here.  We'll assume the boost we get from the currents approximately compensates for the reduction in velocity from any additional biological growth.  70 days from now puts us in the CODAR field sometime in early December, just after Thanksgiving break in the U.S.

090926_ru27_alt_paths

Thats the best we can do.  If Scarlet stays healthy and avoids any catastrophic collisions, timing depends on the unknown biological growth rates, and whether we hit head currents or tail currents.

 

Weekend Waypoints

Friday, September 25th, 2009

The North Atlantic Fleet has 4 gliders deployed this weekend.  The Scarlet Knight (RU27) just north of the Azores, Teledyne's Drake in the tropics, and RU22 and RU23 on a parallel NOAA/Navy mission on the Mid-Atlantic Bight continental shelf.

090925_fleet

Frist Drake in the tropics.  We continue making progress to the NE, experiencing small depth averaged currents that do not line up with the surface geostrophic currents.   We'll move the waypoint north a bit at the next surfacing to keep it at a good distance and head up in between the two eddies, hoping that some of these surface currents extend deep enough to give us a push. 

 

090925_drake_alt

Out by the Azores, The Scarlet Knight is now 1175 km from the target point off Vigo.  The waypoint will be adjusted the next surfacing to try to fly perpendicular to the southward flowing current jet and into the next eddy.

 

090925_ru27_alt

 

Off New Jersey, we have two gliders running side by side across the shelf.  RU22 is the IOOS glider on a MACOORA mission to support fisheries. Running alongside it is RU23, the first to resemble the Navy hardened gliders being built for LBS-G.  RU23 is testing the new lithium rechargable batteries and the new Seabird pumped CTD.  RU22 & RU23 are running side by side as an extended sensor comparision test between the old Seabird and the new Seabird.  At the end of the Tuckerton Endurance line, RU22 will break away and head south on its IOOS fisheries mission.  RU23 will turn and return on the Endurance line, heading back to shore.   At the beginning of this deployment, we also put RU10 in the water, the first of the NSF smart gliders with the larger computer capacity on board.  It was running local tests nearshore while RU22 and RU23 were deployed.  The same boat trip simultaneously supported NOAA, Navy and NSF glider missions.  While RU22 is heading south towards the UMaryland glider port, RU05 is being prepared with a full optics package for deployment out of the UMass glider port with the intention of heading back to Tuckerton to support the ONR MURI program.   All three gliders will provide data that supports the NOAA NE fisheries fall survey, and are being used in preparation for the NSF Ocean Observing Initiative CyberInfrastructure test scheduled to begin in November.   Looks like a good weekend watch gliders in your favorite part of the North Atlantic. 

090925_marcoos_sst

If anyone else is flying gliders out there in the North Atlantic and wants their track posted on the North Atlantic fleet blog, just let us know.  We'll figure out a way to get your track feed up on the google earth interface so we get an even better picture of the international fleet.

Scarlet exits an eddy, Drake heads in.

Thursday, September 24th, 2009

The Scarlet Knight is crossing into the southward flowing jet on the eastern side of this clockwise eddy.  Our target is to cross this jet and end up on the southern side of the counterclockwise eddy just to our east.  That should give us a push to the edge of the red oval.  Crossing the red oval is the present area of study for our class.  We have good agreement between altimetry and hycom just south of the white line that heads to Vigo.  Currents are extremely weak in this area.  Its about 200 km to cross it, with nothing but Scarlet's own velocity.  It will be a long 10 days if that is our route.

090924_ru27_alt_hycom

In the tropics, Teledyne's Drake continues heading NE in weak currents. We hope to catch some help from the eastern edge of the eddy we are approaching.  Its one of the few places we see currents to the NE.

090924_drake_alt

The jump to full speed

Wednesday, September 23rd, 2009

The Scarlet Knight continues to speed across the western North Atlantic. There are a collection of reasons, the main one being our friends at Puertos are urging us to get across as fast as possible to avoid the high waves of winter.  We also are over 75% across and still have over half the predicted amount of battery life on board.  So we purposely speed up Scarlet to fly at our maximum forward speed pitch of 35 degrees.  This uses more energy.  The second modification grew out of an ONR glider data assimilation meeting in North Carolina last week.  Sitting with the Hycom ocean forecasters from NRL, and with all of us looking at how well Hycom was doing in this part of the ocean, we felt this was a good place for a data assimilation test.  With what appears to be extra power on board, we turned the CTD on full time, eliminating the need for the morning CTD cast to make the daily Navy assimilation cycle.  So for at least the duration of this data assimilation test, we'll keep the CTD full on.

Right now Scarlet is crossing the southern side of a clockwise circulating eddy through a region of low currents on the southern side.  This was a gamble we took over the weekend.  Should we go all the way around the top of this eddy to the north, or should we try to cut across what the altimeter and hycom say is a low current patch on the south.  We decided to try flying directly through the low currents, and sure enough, the guidance was right.  As soon as we got into it, the currents dropped to 2-4 cm/sec.  We'll continued across this patch and into the counterclockwise eddy to our east. 

090923_ru27_alt_zoom

 In terms of forward progress, we have just flown past 25 W, so we have less than 15 degrees of longitude to cover.  Total distance as the crow flies is about 1230 km. We have flown 6,120 km.  The present area of concern is centered on 21W, and circled in red.  Beyond this red circle, there is a clear path with a tail current straight across to Vigo.  The problem in the red oval is that there is no clear place to cross it efficiently.  Do we go up around to the north with the currents, or try to go across the low current zone in the south.   We'll be looking at the other products for guidance.

090923_ru27_alt

 

 Here is the Sea Surface Temperature imagery showing the cold water inside the oval.

090923_ru27_sst_alt

 Here's the hycom forecast of SST and surface currents.  Again, cold water in the oval.  As we noted last week at the ONR meeting, Hycom is providing us excellent guidance.

090923_ru27_hycom

Now when we zoom in to the hycom currents overlaid on the altimetric currents, we see many regions of excellent agreement.  Jets  and eddies are seen in both.  But one of the major areas of disagreement is right along the yellow line straight to Vigo.  The altimeter says we will encounter a head current along this path, while Hycom says the eddy is more round, the adverse currents are further north, and we'll have calm currents if we just follow the line.

090923_ru27_alt_hycom_sst

 

This is the perfect set up for a data assimilation test.   Some small differences between data and model, an adaptive sampling glider on the scene, and high interest from a lot of people watching.  So we'll be working on the Hycom model from this side of the Atlantic while Antonio and Dave Kaminsky work on the ocean color from the other side.  The objective is to find us the best route to cross 21 W.

Filament to Filament at Full Speed

Thursday, September 17th, 2009

Teledyne's Drake continues east leaving the regions largest eddies behind, heading toward the smaller eddy center towards its NE and the route to 26 N. We will continue to close this distance today, setting ourselves up for a Friday waypoint change that should hold us for the weekend.  Drake is amazingly easy to navigate.  It is one of the differences we are seeing between deep and shallow gliders.  The deep depth averaged currents have been so much smaller for Drake, making it easier to choose where you want to go. Scarlet, on the other hand, is a shallow glider, built for speed and built to take advantage of the stronger currents you get in the surface waters.  Faster flying and faster currents mean more way point changes.    Having the two gliders out at the same time nicely demonstrate how we'll be operating in future science campaigns, where you have a mix of several gliders deployed at the same time, some deep, some shallow, with the exact numbers depending on the type of science mission.

090917_drake_alt

We are now on an approximately weekly phone call schedule with our partners at Puertos del Estado in Madrid.  Together we have moved our target point south a bit to 42.25 N, 10.25 W, just offshore the port of Vigo, staying outside of the shipping lanes.  With one ship transiting the 10 W shipping lane every 12 minutes, we don't want to take chances with this glider in the region.  Exploring how you successful cross this region is a job for another glider on another day. The total distance between Scarlet and this location is just under 1400 km.  For back of the envelope numbers, we often take 20 km/day as a typical distance made good, so thats 70 days, with wide error bars.  Yesterday we increased the pitch angles that Scarlet is flying.  We want to give her as much speed as possible even if it burns more energy.  For the rest of this mission, the race is with time.  We are racing the coming of winter, and the potential for more biofouling on the glider itself. 

090917_ru27_sst_alt

Zooming into the Scarlet's location, we were concerned yesterday by the strong currents to the SW, opposite our intended direction of NE.  Was our altimetric roadmap wrong?  We were getting used to having good guidance products.  The satellite sea surface temperature and ocean color images from the Canaries did the trick.  In the image below, we see the colder blue water heading south, with the western half curving around to the SW, and the eastern half curving around to the SW. We were still in the western half, so we adjusted our waypoint to pull us out of this part of the filament.  This morning's currents reported by Scarlet indicates that move was successful and we are now heading into the colder water that curves to the east. We'll make our new waypoint along the straight line to Vigo.

090917_ru27_sst_alt_zoom

Zooming back out to look at just the geostrophic surface currents from the altimeter, we see there are still several north-south filaments to cross.  We are just east of 27 W,  and the filaments extend to 19 W.  From 19 W to 10 W, there is a nice current that heads eastward towards Vigo that we are heading for.  We'll keep watching this area over the next 70 days or so to see how it evolves.

090917_ru27_alt_best

Another Semester Begins

Tuesday, September 15th, 2009

Frequent readers of the glider blogs usually know that a break in the blog means trouble. But not this time.  In this case it was just the start of classes - our first regular full week here at Rutgers.   The Atlantic Crossing class has about 30 undergrads in it this semester.  A 10-fold increase over the last 2 years.  Nothing like having gliders at sea to build student interest.  We also have our graduate student visitors from the Azores and Canaries adding their local knowledge and a slightly different perspective on the last 600 years of maritime history. Josh and I divided the class into 10 working groups this morning, each led by a veteran undergrad from last year.  Each student team will work on a different aspect of the Drake and Scarlet Knight missions.  

Drake, the Teledyne Webb Research thermal glider, has completed its run in the jet between the two counter-rotating eddies and is heading into slower moving waters.  Our objective is to continue riding the currents north (white path) to about 25-26 N, and deterimine if we can occupy on of the historical sections across the Atlantic originally run by the Research Vessel Chain out of Woods Hole.  The thermal glider is responding amazingly well to the waypoint changes - an advantage of going deep - 1200 m in this case. The currents are slower, and we can use the glider speed to manuever more.

090915_drake_alt

Moving east across the Atlantic to The Scarlet Knight, she has already crossed the front discussed in the previous blogs and is well within the southward flowing cold water.  We'll keep heading her east towards our present estimate of a pick up point - 43 00 N, 10 15 W.  This is our estimate of the outside edge of the shipping lanes, to be refined as we get more of the maps into google earth.  Distance from our present location is just under 1420 km.  Underneath the semi-transparent SST are the geostrophic currents derived from the altimeter.  Good agreement appears to be the norm in this part of the ocean.

090915_ru27_sst_alt

Zooming into the location of The Scarlet Knight, we see that she is continuing to fly east across a strong jet of southward flowing water.  Yesterday we were on the western side of this jet that heads south to Faial.  Today we are crossing on to the eastern side, in currents turning around a counter clockwise rotating eddy that should give us a boost towards Spain.

090915_ru27_alt

We had a good question on the previous blog entry - do we have to make is to Spain to be successful - or is a pickup in Portugal also a success?  For us, a pick up anywhere on the European side is a success.  In fact, our Atlantic Crossing class is planning for an entire series of possible pick up points along the full west coast of Spain and Portugal.  We are aiming for Spain because last year, a CODAR HF Radar network was installed on the west coast of Spain near Galicia.

http://www.puertos.es/externo/clima/Radares/Galicia/galiciadeseng.html

This is a significant collaboration by many groups within Spain. The Galicia High Frecuency Radar System is owned by Marina Mercante (the General Management of Merchant Marine), dependent on the Spanish Ministry of Public Works. The installation of the units at Finisterre (A Coruña) and Cabo Silleiro (Pontevedra) lighthouses was posible thanks to an agreement among A Coruña and Vigo Port Authorities, Marina Mercante and Puertos del Estado. The technical-scientific exploitation of data is conducted by Puertos del Estado and two Galician Regional Ministries: Consellería de Medio Ambiente, Territorio e Infraestructuras and Consellería do Mar. 

090915_maparadar

The CODAR ( http://www.codar.com/ ) HF Radar network provides surface current maps every hour in this region offshore Spain.  Our job with the glider is to pull up as close as we can to the shipping lanes, and then loiter offshore as we wait for a pick up.  Having real time surface current maps as you approach the coast will make it easier for us to manuever the glider, and that will make it easier for our colleagues at Puertos del Estado to help us with a pick up.

http://moises.puertos.es/Redes/DatosRedes.php?codigo=6291&Formato=Grafico&Lenguaje=eng&tipo=map

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Exploring the Ocean Mesoscale.

Saturday, September 12th, 2009

A rainy morning here in New Jersey, perfect for fine tuning our steering on the Trans-Atlantic Gliders. First Rutger's Scarlet Knight is trying to cross a series of three alternating warm and cold filaments. The warm filaments are moving north, the cold ones south, and we are trying to fly east. We are in a warm filament and are 35 km from the edge of the front where we cross into the cold.

090912_ru27_sst

According to the altimeter, we just flew across the center of the eddy and have entered the southward flowing side. We need to fly east quickly now, so we can jump into the southward flowing current of the eddy just to our east. As we are advected south, if we don't get far enough east, we continue spinning around in the eddy we are now in. If we do get far enough east, we get whipped around the next eddy towards Spain & Portugal, achat cialis pas cher.

090912_ru27_alt

Back to the tropics, Teledyne's Drake is doing the exact same thing. We are flying eddy to eddy. In this case we just left the eddy to our south and are now entrained in the eddy to out north. We are using the glider speed to choose an exit point the puts us as close as we can get to our next eddy of interest. We are often amazed how a surface current measured from an altimeter in space can be so well correlated with a depth averaged current measured by a glider that is undulating between the surface and 1200 m, but this highlights the dominating influence of the ocean mesoscale.

090912_drake_alt_b

In oceanography, the eddy fields we are navigating the gliders through in the above images are known as the energtic ocean mesoscale. http://en.wikipedia.org/wiki/Eddy_(fluid_dynamics) . When we look at our ocean from satellites in space, we see the mesoscale eddies are everywhere. They dominate any image of the ocean, just as the weather patterns dominate any image of the atmoshpere. http://www.gfdl.noaa.gov/ocean_mesoscale_eddies . One of the challenges of climate prediction is that most climate models that include the ocean do not yet resolve this energetic mesoscale. http://www.clivar.org/organization/wgomd/meso/MESO_summary.pdf . This short executive summary of a recent meeting of the world's experts on this topic indicates it may take a generation of researchers to fully understand the impact of the ocean mesoscale on climate. That generation of researchers will be made up of the students currently sitting in our classrooms. This is why government agencies, universities, and companies are working together on projects like this. It is why the COOLroom is on a university main campus, why these two gliders are crossing the Atlantic, and why there are over 100 school districts with letters on board.

09/09/09

Wednesday, September 9th, 2009

Last night I wrote up the blog on the New World Record for along-track distance just set by The Scarlet Knight.    I get up in the morning and the next thing in my email box is this image from our friends in the Canaries. Scarlet tacked 40 kilometers onto that total today.

world-record

Currents reported by Scarlet are in excellent agreement with the geostrophic currents from the alitmeter.  We'll move the waypoint a bit north at the next opportunity.  We want to cross the present clockwise eddy a bit north of the center, and enter the southward flowing current in a region that gives us more time to drift south as we fly across it.

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Overlaying a semi-transparent SST, the agreement between the temperature and current structure from two different satellites is amazing. We'll continue our general path to the ENE into the cooler water towards the northern edge of Spain.

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Back in the tropics, Drake is in the middle of the eastward flow jet between the two counter-rotating eddies.  We'll move the waypoint north to start flying across the jet to get to its northern side.

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Scarlet Breaks the World Distance Record

Tuesday, September 8th, 2009

The Scarlet Knight (RU27) surfaced at noon today, collected her GPS location, and recorded a total path length of 5,702 km, breaking the World Record for alongtrack distance set last year by RU17 at 5,700 km.  From now on, every surfacing pushes the World Record higher. The tracks of the two gliders are shown below, with RU27 in white and RU17 in yellow, both plotted over the sea surface temperature that shows today's meandering Gulf Stream.  There are remarkable similarities. Most striking to me is the wall both gliders hit near 45 W as they left the Gulf Stream Meander and Ring region and entered the Gulf Stream Extension region.  At this interface, both gliders encountered a strong eddy that they had to fly around, a diversion that was followed by a jump to a more northerly course.  RU27's improved design as well as the improved environmental guidance has enabled us cover that path length faster than RU17, and to stretch that path length out over a greater east-west distance. 

090908_ru27_ru17_worldrec_good

Plotting the tracks over the bathymetry, The Scarlet Knight is now directly over the rift valley of the Mid-Atlantic Ridge, the longest mountain chain in the world.  We are leaving the North American Plate and starting to fly over the Eurasian Plate http://en.wikipedia.org/wiki/File:Plates_tect2_en.svg

090908_ru27_rift_valley

We've adjusted the areas extracted from the global CCAR altimetry product and the NRL HYCOM forecast model, setting them up to cover at least the region from 30 W to 10 W.  This sets up the final U.S. guidance products.

090908_ru27_alt_hycom

And now the Europeans get to try their hand at flying.  In the photo below, Dave Kaminsky (white hat), now in his senior year as a student at Rutgers, is introducing our European students Al, Adrian and Fillipa to the processing and display codes for the satellite ocean color imagery Antonio sends us from the Canaries everyday.  The European students will help us get the European guidance products into our Google Earth flight planning displays over the next two months. Displayed on the big screen is the track of RU27 as it crosses the rift valley and breaks the world record. 

world_record