Archive for November 12th, 2009

16 Kilometers & The Coolest 20 Years

Thursday, November 12th, 2009

Gliders on both sides of the Atlantic are getting hammered by storms tonight.  But thats ok.  They are underwater gliders.  They can handle it. They are what we'll use to explore some of the most extreme environments on the planet.

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Zooming into the East Coast of the U.S., we get ready to close out the intense Mid Atlantic fall sampling season with the remnants of Hurricane Ida.  White is clouds, green is rain.  An amazing storm. Flooding along much of the east coast today on TV.

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Look below the clouds and see one of the most amazing sights on the planet.  A full scale regional coastal observatory running full bore through the storm.  Satellites grabbed the initial sea surface tmeperature condition pre-storm. The full CODAR network was ready for this one, and the undergrads put it into google earth for the old guys like me to use.  The gliders had an amazaing fall.  First the 4-glider joint IOOS, Navy, ONR, NSF survey timed to the NOAA fisheries survey for the NOAA Fate program.  Then the NSF OOI CI IO OSSI (I love that acronym). I lost track of how many AUVs and gliders were in the water, all being directed by the CyberInfrastructure software pulling data from the MARCOOS forecast models. Followed by this week's combined NSF OOI and DHS Center of Excellence field test.  We had more satellites looking at the Mid Atlantic through that high pressure at the beginning of the week than every before.   Now we end with a severe storm with the hottest set of optics gliders ever deployed.  The grad students were drooling over the storm sediment transport data this morning, pulling off page after page of their next thesis chapter.  On monday we'll start assembling it for the optics folks meeting down at Stennis right after Thanksgiving - Steve & Joan should get a kick out of it.  Its been 20 years to go from vision to implementation. An amazing journey.

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Speaking of 20 years, its been 20 years since Hank Stommel's article on the Slocum mission appeared in Oceanography.  Now Drake is holding the line on climate change.  Doug Webb has brought these gliders from vision to fruition in that time, and we hope he is also looking back at the last 20 years as an amazing journey.

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Speaking of amazing journeys, Scarlet is now just over 16 kilometers from the Spanish EEZ. Currents have dropped down to about 6 cm/sec, so we only made about 6 kilometers distance during the last 8 hour segment.  We'll continue heading northeast.  It could be a very different blog this time tomorrow night.

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Zooming out we see Galicia. We are trying to ride the currents to the east a bit towards shore, then think about turning north into the yellow circle to avoid the most intense vessel traffic.  It looks like there was some interest from the local newspapers today.

http://www.lavozdegalicia.es/vigo/2009/11/12/0003_8101106.htm

 

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Another sign we must be getting close. Instead of a map, tonight Antonio sent us a picture for good luck.  It is "The Guardian of the Bight". In the center is Breogan, the first Celtic Galegian King, a sailor and adventurer.  To the left is The Hercules Tower, built by the Romans in the 2nd century as a light house that is still in use today. As Antonio said, to the right is the sea, and The Scarlet Knight.

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Below is the Investigador, the buoy tender used by Puertos del Estado.  She is 47 m long.  Crane, A-frame and Zodiac.  All things that make a glider recovery team happy.

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Nor’Easter! A big one!!!!!

Thursday, November 12th, 2009

As highlighted by David, the Mid-Atlantic got hammered today.  This was an epic event and caps off the 2 weeks of great efforts.  We had one week of calm conditions that allowed us to test several behaviors for the glider fleet, yesterday a very diverse group we coordinated a mission (based on community, not science), monday-tuesday model differences coordinated the fleet and tonight we face the strong fury of the nature awakened!  The general mission uploaded to the fleet today was to simple, try to hold position.  The currents have been building, and coastal innudation has been knocking out the CODAR sites, but as an ocean going person, all I can do is appreciate the awesome power of an angry sea and hope all people are safe.  The building CODAR currents are shown below, the sites being knocked out by the storm are denoted by the red dots in the last picture.

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The weather and ocean models all showed the big storm. The weather model showed the big southwest winds.  Weather forecasts for tonight is starting to show the reversal of wind, and down south the eye is visible.

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The ocean models all show the storm.  There are differences between the models but the strong southward flow is present in  all the models.  Yi and his group this week added an objectively weighted model ensemble.  The lowest two figures show the difference between the mean and objectively weighted ensemble model.  The mean ensemble definetely showed weaker southern flowing currents. There is alot interesting science to explore lining up the observations, weather model, and ocean forecasts.  The differences in  the picture to speak opportunity, and despite the variances, the fact I use observations, multiple models and see a "relatively" similar ocean is awesome.  What a great time to be an oceanographer and environmental scientist!

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So these features are dramatic, let us check on our intrepid sea going gliders tonight.Not surprisingly, the gliders lose!  Most are being advected south, the northern glider is not impacted suggesting the southward wind driven currents is variable over the shelf.  Models support this. The depth variability in salinity  in the cross shelf have not changed dramatically.  What little temperature structure we saw in the water column has been erased.  This is coincident with a decline in chlorophyll.  Not surprisingly however, as the winds and waves pick, particle loads increase as seen in the optical backscatter.  The SEDIMENT & SAND returns for a late night Nor'Easter party.  As my Spanish colleagues often say "Force wind and honour all".

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23 kilometers

Thursday, November 12th, 2009

Antonio sent in a series of images this morning based on the model currents. In those images we see that current flowing south along 13 W as the main feature in front of us.

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Guidance from U. Colorado from the satellite altimeters similarly has that current flowing to the south along 13 W.   Altimetry also says there is a strong current to the east just inside that green zone on the chart below.  We want to head towards the northern edge of that eastward current.  That approach would allow us to jump into the counterclockwise rotating eddy marked by the yellow circle.    As planned, we moved the waypoint 15 minutes to the north.  This moved our heading from 60 degrees to 45 degrees.  We are heading NE as planned.   Scarlet just surfaced right at the western edge of a jet to the northeast that we see in the altimetry.  In fact, she is directly beneath one of the arrows on the map.  We hope to follow this current into the Spanish EEZ.  We are about 23 kilometers  directly offshore of the Spanish EEZ.  The distance along our heading of 45 degrees is 27 km.  Scarlet just flew about 6.5 km during the last 8 hour segment. If this continues we should be within a couple kilometers of the Spanish EEZ  tomorrow at the 11 am surfacing.  That makes the most likely crossing point the 7 pm surfacing (U.S. east coast time) on Friday.  Looks like my students will need to show up for class tomorrow at 11 am.  We'll continue to refine the estimate every 8 hours with each surfacing.

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29 Kilometers

Thursday, November 12th, 2009

Our friends at Puertos del Estado http://www.puertos.es/es/index.html are doing an amazing job preparing for Scarlet's arrival in Spain.  Our partners there, and the many critical oceanographic measurements they maintain and make available on their website, made Spain the natural choice for landfall on this trans-Atlantic mission.

 

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Checking in on Scarlet first, we see she is now 29 km offshore of the Spanish EEZ.  The morning currents are to the southeast.  The wobble we see between northeast and southeast currents  is characteristic of an easterly current with inertial waves superimposed.  Inertial waves usually are an indication of an abrupt change in the windfield, often due to a storm.  The inertial waves spin in a horizontal circle and often persist well after the storm has passed.

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Checking the google earth clouds (white) and weather radar (green), we see a storm slamming into the U.K., and a line of clouds that trails off across the northwest tip of Spain.

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Checking the ship observations and surface pressure field, strong winds are heading at the northwest tip of Spain.

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Checking the wave forecast, we see the strongest waves are offshore and to the northwest of Spain.

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Checking into the Puertos website, we see the wave heights are still low for Spain, running 2-3 m, well below the 8 m high waves we experienced over the weekend.  Amazing how your perspective changes.  We are looking at 2-3 m waves and thinking the weather is good.  Puertos has warned us to expect severe weather.  We hear that out on the recovery vessel, the weather will either be bad or awful.  Its the first time we are hoping for bad weather.

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