Archive for July, 2010

‘R U COOL?’ Library Dives Deep With Oceanographers

Thursday, July 22nd, 2010

http://fb.me/CLc1zY4E

Dunes are key to beaches, Avalon lauded for preservation approach

Thursday, July 22nd, 2010

http://fb.me/FA9c9bzI

Honouring Cook

Tuesday, July 20th, 2010

Hey all

just before dissappearing, Cook, the brave droid, was investigating the heat transport on the 26.5 N segment. However, SSHa fields posted by the students/scott/ulpgc also showed that Cook flied a fascinant segment of some -engaged- gears where the current forecast data sets seemed to agree and to disagree periodically.  Thus, our brave Cook gave some good opportunities to do some data assimilation experiment/comparisons (Figure 1) like this shown in the post.

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Figure 1. SSHa showing the data assimilation segment from 59 to 53 W (1 jun -7 jul 2010)

 We compared 3 data sources: NCOM, NLOM Global model current data (1/8º and 1/32º respectively) VERSUS the drift current field calculated by Cook during the surfacing-diving stint period. Thus, using the speed and direction of both global models we evaluated the forecasted diving lat-long 12 min after (when diving) (Figure 2). 

 Figure 2.- Ground true Cook´s current  VS ncom/nlom forecast.

 Results show some fascinant findings (figure 3). We found 16 BAD disagreement (red colour) in 35 days (14 NCOM 1/8º and 10 NLOM 1/32º). The scale seems to affect the data agreement between them (some strong dissagreements in direction and module between both NLOM and NCOM data). It could be explained by the different data scale resolution (12*12 km2 vs 3*3 km2), NLOM data are able to target submesocale features while NCOM could not observe them, since the scale for targeting would require data sets down or equal of 6*6 km2.  Results also showed that these disagreement/agreement segments affect to different areas/periods.

Figure 3.- Rose of currents NCOM (violet) and NLOM (blue) in 3 stints.

It looks to keep a periodic oscillation of the errors... In some cases (second stint)  it looks to exist an strong disagreement between both directions and over/sub estimations of the module. The best sting /(undoubtely) is the third (the last 2 weeks).

The periodicity also seems to be preliminary explained in the figure 4.  Data seem to to show why this periodicity. The southern part of the 2 MESOSCALE GEAR seems to generate the strongest variation. Especially in those areas with a strong SSHa gradient.

 

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Figure 4. Current roses error areas and the SSHa landscape.

 And finally (figure 5) the hole COOK stint (look that data assimilation began at 59 W). Global data seemed to agree (green/orange) by different periods/areas,  at the beginning, but especially, at the end when Cook flied the 53s W.

 

Figure 5. Cook pathway. Data assimilation of this blog began in the 59 W.

I expect you enjoy that. It is only a modest contribution honouring Cook and his incredible job at sea. THANKS Cook !!!. And thanks to the people of the other side (RU, under and postgraduated students, ioos,webb, navy, noaa.. ), and to the people of this side (PLOCAN, qualitas, PE). Reasons are obvious: your inmense job.

Finally let me thank my great ULPGC team/colleagues/FRIENDS, Jorge, Enrique, Dani, Josep, Pep and Alex.  I have forced the machine (a lot !)  to have this. But I understood that a data assimilation comparison (3 scales) with a glider in the middle of the 26,s N Atlantic big blue was an inedit opportunity.

Honor all,

Antonio G. Ramos

Disappearing Act on Magical Line

Wednesday, July 14th, 2010

As of 7/7/2010 at 14:37 Cook has been missing in action. It has been 170 hours since Cook last called. We have talked to Webb and they don't see any scenario where it will come back. We currently have no indication why we lost Cook.

Cook was out for 108 days, and was about 350 km from where Drake went down after 104 days last year. We are examining possible causes for Cook's loss and seeing if there is any correlation with Drake.

Cook was a brave droid who died in battle. He collected excellent data which we will continue to analyze.

We'd also like to take this moment to thank our partners in Spain. Your forecasting and analysis have been incredibly critical while piloting the glider. We'd like to thank you for your time, effort, blogs and Skype sessions. Working with you on this mission has be an honor and a joy. We look forward to continuing our relationship in the future.

http://www.nytimes.com/2010/07…

Tuesday, July 13th, 2010

http://www.nytimes.com/2010/07/13/science/13canyon.html http://fb.me/z9nQyyYn

The 26º30' N magic line.

Monday, July 12th, 2010

Hola a todos ¡

Scott posted some days ago the important mission of Cook: To investigate the heat transport in the N Atlantic flying the 26.5 N straight line from W to E. As he explained, data assimilation mission would change the flying procedures for Cook. However, the 26.5 N seems to be an “interesting” and magic line. And this magic line is giving a great opportunity to do both.

The tonic of the last months has been a “periodic-like” agreement (63-59 W) – disagreement (58-55 W)- agreement (54-..W) when compared the different current data sets outputs (Cook Ground True vs Global Models). The Figure 1 (SSHa field) confirms that Cook flies on the south border of a N warm eddy and briefly we would find SW oriented currents. 

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Figure 1.- SSHa fields (10 jul 2010).

However, the most important remark of this blog is related with a data assimilation  opportunity. Students made some weeks ago a great job showing 3d hycom data with the vertical profiles found during the COOK flying in the Centre of a gear/flower SSHa anomaly. They founded strong subsurface contrary currents that could explain this disagreement between surface current field and these integrated by cook at depth (ground true).

 Cook right now looks to sail/fly from gear to gear. And look that we have 4 of this incredible gears  in the magic 26.5 N line… That would mean that soon, we would have (if periodicity repeats) a new “disagreement” event ahead…

I would suggest to repeat similar profiles to these observed some weeks ago: We could better understand the stints where models forecast seem to work or not (!!). And it would be really fascinant to find TWINs depth profiles and, for instance, twins currents outputs dissagreement.     

 Expect that you enjoy !

We are doing right now in Spain. Our little and magic country feels today really proud and floating  in a colective cloud. Yesterday our great soccer team " la roja" (the red), won the world championship in South Africa by first time in our history.  

viva España !!!!

Force,  wind,  sea and  honour all

Antonio G. Ramos

 

Karl Nordstrom has been using …

Friday, July 9th, 2010

Karl Nordstrom has been using a beach in South Jersey for a multi-year study. Thursday, he released his findings,... http://fb.me/ErQcPuhg

Strong border lines

Tuesday, July 6th, 2010

hey all
enclosed find the SSHa and the current fields.

Cook is flying the Southwestern border of a warm eddy (figure 1). He would find a sudden change on currents some miles ahead, In the S corner of the warm eddy, first flowing NW and then flowing SW. Both seem to be strong currents (black colour > 0.6 knots).


Figure 1. SSHa. 5  july 2010.

Global models derived current fields show that Cook flies strong (>0.6 knots) N-NW currents (figure 2). It will be interesting to confirm if Current fields reported  by Cook validates it. Just in the last stint (58-54 W), when Cook crossed the S border of the Meccano/lily feature centrum (strong SSHa gradient), the global models derived currents disagreed with Cook,s reports.Right now,  he is arriving to another interesting area with a strong border line (SSHa gradient).

Current fields 5 jul 10. Up Total Current field. Down Geostrophic Current field. In black > 0.6 knots.

Figure 2. Current fields (black >0.6 knots). Total (up) and

geostrophic (down) current fields. 5  july 2010.


I Expect that it will be useful.

Force, wind, sea and honour all

antonio

A U.S. July 4 Holiday Report on July 5

Monday, July 5th, 2010

Figure 1: Here we take a look at the track of Cook on the basin scale.  At the end of last week we set the next waypoint for Cook as the top of the Mid-Atlantic Ridge.  This will be the section of the flight that the summer students concentrate on.  Lets see if we can make the European side of the Ridge before they leave.   Once on the European side of the Atlantic, we set our sights on the fall transit to the Canaries.   The present distance to the Canaries is about 3,500 km.  If we look at our progress along 26.5 N, we made the turn back on May 11.  Since making the turn, we have traveled 1,150 km.  In 6 days we'll take another check to see how far we have made it in 2 months.  Still we know the approximate numbers.  We took about 2 months to go 1/4 of the distance to the Canaries.  Maintaining this average speed gets us to the Canaries in another 6 months - again - not a great time to be out on the North Atlantic in small boats.  We also have to worry about the thermal engine, and how much temperature change we need from top to bottom.  We like to have a 15 C temperature difference, but can we live with less?  A good question. That is about the time that the surface to 1200 m temperature difference reaches a minimum, giving us another envelope to push.  So there is a lot of talk right now between our students in the U.S. and our friends in the Canaries.  What temperature range do we expect this winter, and how will Cook handle it?  Should we give up trying to maintain the 26.5 N line, and instead use the currents to our advantage to speed across like we did with RU27?

Figure 2: Lets look at the HyCOM forecast, this time for sea surface height (color) and surface currents (black arrows).  The Cook currents have been switched to red so they show up.  We are presently going against the current that is circulating clockwise around that sea surface high to our north in red.  HyCOM says small currents are on the way as we cross into the blues.

Figure 3: Overlaying the HyCOM currents on the satellite sea surface temperature map gives us a lot of confidence in HyCOM.  We see lots of features in the forecast currents lining up with the fronts and features in these satellite observations.

Figure 4: But now we overlay the HyCOM currents on the satellite altimeter sea surface heights and geostrophic currents, and we loose a little confidence in the model in some regions.  Here we see that some features are lining up with HyCOM & the satellite SST, giving us strong confidence in these features.  But some are not lining up.  These we have less confidence.  if we had time, and our mission was data assimilation, we would head Cook straight into these regions of disagreement.  If we are racing against time, we do the opposite, and head Cook into regions with known favorable currents.  But in our case, we are still on a heat flux science mission, so we'll maintain this line for as long as we can and still make the Canaries.

SST fields in the NE Atlantic

Sunday, July 4th, 2010

 

good morning !

Just a little remark about the cook deadline in the NE atlantic.

Enclosed find the figure 1a and 1b (GAC-9*9 km2, monthly) NOAA satellite derived SST fields for each month (promediated) since 1985 to 2005.

 Figure 1a. Satellite derived GAC SST images from 1985-2005. January – June.

 Figure 1b. Satellite derived monthly GAC SST images from 1985-2005. Jul – Dec.

If you need 15º C of difference between the surface and the 1200 m (=5º C) to operate Cook efficiently, it would mean > 20º C in the SST. In the image, the problematic window appears in blue-violet colours. Look that January, February and March do not seem to be suitable months to fly COOK at north of the 26 N. It would be necessary to increase the speed and leave the canarian water before winter (jan,feb.mar) arrives.

I also include a calcule of the anomaly of SST from 1985-2005. The SST has increased 1 C in this water the last 20 years (figure 2).

 

Figure 2. Yearly SST anomaly from 1985-2005.

I expect that it will be useful

antonio