Tag: Nilsen Strandskov (Page 4 of 11)

Hey All,

So over this past week, I have been working on plotting up some data from Silbo’s mission so far and then also spent a little bit of time comparing his data to a near by Argo drifter.

Figure 1. 3d temperature plot of Silbo's track from Iceland to the Azores

Figure 2. 3d Salinity plot of Silbo's track from Iceland to the Azores

In figures 1 and 2, we can see how much the water conditions have changed from being almost uniform in temperature and salinity from surface to 1000m depth to being strongly stratified near the shores of the Azores.

Next I plotted more recent data, comparing Silbo’s temperature and salinity to what was recorded by a near by argo drifter, coriolis 6900511.

Figure 3. Temperature and Salinity profiles from Argo unit Coriolis 6900511

Figure 4. Temperature as recorded by Silbo

Figure 5. Salinity as recorded by Silbo

Although the Argo drifter went down another 1000m past what Silbo is capable of, the data shows a very nice correlation showing nearly the same shapes and depths for the thermocline and picnocline.

Nilsen

Hey all,

So Silbo is still barreling on his way towards Madeira as the currents continue to unfortunately be favorable.  With the way the currents have been moving, it seems we may need to take some sort of evasive maneuver to prevent ourselves from getting too close to the island where we will find unpleasant bathymetry and some pretty heavy ship traffic.  The most likely scenario would be to station keep for a while (fly between two close waypoints) until the team with the drifter can get out there to inspect silbo and deploy the drifter.

Figure 1. Hycom Density

In the image above of density along with the images below from the hycom model, we can see that Silbo continues to ride down hill along the mesoscale as he heads towards his waypoint.  According to the models, it looks like if we were to go north a bit and fly with our nose into the cold eddy, we could slow ourselves down.  This could solve our problem of hitting speeds up to .45m/s

Figure 2. Hycom Salinity

Figure 3. Hycom Sea Surface Height

Figure 4. Hycom Temperature

Figure 5. Myocean Surface Conditions

Now looking at the myocean data to see what is going on throughout the water column, the salinity really portrays the best idea of what Silbo is dealing with subsurface.

Figure 6. Myocean Salinity at depth

Figure 7. Myocean Currents at Depth

Figure 8. Myocean Eastern Zonal Component currents at depth

It seems that deep salted cold fluxes of Mediterranean water have increased flow into the atlantic over the past couple months.

During the winter, the convective cell NW mediterranean is really intense (transmitting heat to the french, spaniard, italian coasts thus preventing its freezing.  This cold salted water sunk and streamed along the eastern coast of spain, flowing south and then left the mediterranean through the straight of gibraltar and sank down to 600 m.  The effects of the out reach of this salted mediterranean layer can be seen in the images showing salinity at 600, 800 and 1000m.

If you look at the salinity for the upper ocean, it is pretty uniform from the surface to 400m. However if you go deeper, Med water appears around silbo at 600 m, and have an affect until his deepest diving depth 1000 m.

Looking ahead, there are some salt driven eddies around him coming from the NE.  This most likely is the explanation of how different the current fields are between the surface-500m and 500m-1000m.

But the Mediterranean will not continue to be a huge driving factor much longer.  There is some cold but fresher water reaching up from the south that keeps the mediterranean waters north of Madeira

Force Wind Sea and Honor

Nilsen Strandskov, Antonio Ramos, & Oliver Ho

But not in the typical sense…

Today Lauren Cooney of TWR gave us an update on the distances/speeds required to reach Madeira within the window of our friends from PLOCAN arriving there to deploy the drifters and provide an optical inspection.

Fig 1. Estimation plots of Arrival in Madeira and the Canary Islands

Shown in the above plots, we must keep an average speed of less than .23 m/s in order to not over shoot the proposed window and miss the rendezvous at Madeira.

Unfortunately, it looks like the surface currents are well against our favor at the moment..

Fig 2. NCOM Currents overlayed with NLOM Sea Surface Height

Fig 3. Hycom Density with geostrophic currents

Fig 4. Hycom Salinity with geostrophic currents

Fig 5. Hycom Sea Surface Height with geostrophic currents

Fig 6. Hycom Sea Surface Temperature with geostrophic currents

Seen above in the images from hycom and nlom/ncom models, the currents at the surface are in a pretty steady flow to the south east in the direction of Madeira.  However if you look at the post from yesterday showing currents at depth, we see that sub surface the currents change direction resulting in the north eastern flow shown by silbo.  This is also possibly due to a warm core eddy that appears in sea surface height in Figure 2 (ncom/nlom) and Figure 5 (hycom).

Fig 7. MODIS satellite imagery of Chlorophyll Concentration

Fig 8. MODIS Satellite imagery of Sea Surface Temperature

The above images are from the modis satellites showing sst and chlorophyll concentrations for the area.  Chlorophyll showing a pretty large bloom up on the northern shores of Spain but relatively low activity in the vicinity of Silbo.  Meanwhile the sst shows the gradual cooling as we move away from the equator.

Fig 9. Silbo's Track on the first leg of the Challenger Mission

Finally, I just wanted to take a step back and admire how much distance Silbo has covered since last June as we are now less than 450 km to our destination on the shores of the Canaries.

Nilsen Strandskov & Antonio Ramos

Hey All,

So there has been quite a lot of activity over the past couple days as we made a few crucial decisions for piloting Silbo.

First off, we have made a few way point changes ranging from east to south east as we are making our way through the eddy solar system we have been flying for the past few weeks.  We have also changed our flight parameters to flying at 300cc instead of 400.  This is to save power as we are no longer fighting strong head currents (which was the causation towards the beginning of the mission to make the decision to move it up to 400cc).  Also in an attempt to save battery, we are continuing to only turn on the ctd for 1 down cast for every two yo dive while doing one dive every two weeks to validate the data collected.

Temperature recorded by Silbo on March 28

Salinity recorded by Silbo on March 28

Density derived by Silbo's data from March 28

As seen in the three figures above, the down cast (blue) and up cast (red) and relatively along the same trend showing that the ctd sensor is still functioning well.

Taking these measures to conserve energy is also proving to be working very well. Below there are a couple figures showing energy consumption, estimated end date for the life of the batteries, and estimated distance that can be covered off of how much energy we have left.

Top: Amps/hr consumed so far Bottom: Estimated end date

Flight Estimation Plots for Silbo

Based on the above plots, Silbo should have enough battery to last until mid June and can cover about 2,500km,  well over the ~750 km track that Silbo will follow to get to the Canary Islands via sailing by the island of Madeira.   The remainder of the trip is estimated to be about another month and half, Madeira being about 3 weeks away.  Leaving Funchal’s harbor, Carlos and a team from PLOCAN plan on running an inspection to make sure there is nothing growing on the exterior of Silbo and will simultaneously deploy drifters in the water.  This will all happen about 50 km west of the island.

In order to most strategically fly silbo  to 50 km from madeira, it would be necessary to keep flying east for a while to make sure we can reach the rendezvous point without having to try and fly back to the north against the southern flow that goes from Madeira to the Canaries.  But once we get past the inspection, it should be relatively smooth sailing as we ride the tail end of the Canary current to our final destination.

To get better estimations of the time for the remainder of the mission, Daniel Hernández, Josep Isern, Enrique Fernández and the rest of the team from ROC-SIANI group at ULPGC used their simulation to see how long it will take Silbo to get to the Canaries.

Pinzon path planning estimation using myocean

Pinzon path planning simulation using hycom

Currents comparison recorded by Silbo (g) hycom (b) myocean (m)

These estimations show we should be in the vicinity of Madeira within the next two weeks or so.  However we may need to delay a bit as we need a little more time for our team to arrive.  However it seems Silbo has plenty of battery power to bide a little time.

Based off of speeds Silbo has reached thus far on the mission, if Silbo maintains a speed of .35 m/s, we are looking at an arrival at Madeira by april 9-13, .3m/s would give us a date of april 11-15, or .25 m/s would land us at april 13-17.

To make sure we find the most ideal path, we have been keeping a keen eye on our various ocean models, both on the surface and at depth.

myocean surface conditions for temperature, salinity, currents and sea surface height

myocean temperatures at depth

myocean salinity at depth

myocean currents at depth

ncom currents and nlom sea surface height

hycom density and currents

hycom salinity

hycom sea surface height

hycom temperature

The ocean models shown above (myocean, ncom/nlom, hycom) all show the general trend in the currents we have seen agreeing with the currents recorded by silbo.  As for now we will continue to follow the way point as we continue to make progress to the east.

Finally, I would just like to point out some beautiful imagery from the modis satellite imagery of the north atlantic of temperature and chlorophyll (where I got the title from).

modis sea surface temperature

modis chlorophyll imagery

check back soon for more updates on Silbo’s journey!

as always, Force, Wind, Sea & Honor

Nilsen Strandskov, Antonio Ramos, Ben Allsup, Lauren Cooney & Oliver Ho

Hey All!

As we all get ready to say goodbye to the weekend and start up the new week, Silbo is gearing up to hurtle over a wall!

HyCOM Sea Surface Height and Currents map

Silbo is coming around the south east side of the cold sun eddy over the next day where he will then encounter what looks to be one of the strongest currents we have seen since redeployment.  Unfortunately it is flowing north and so Silbo is going to have to fight his way across (hopefully without being pushed too far off course) as we continue on our way to the south east towards Madeira and ultimately the Canary Islands.  This afternoon silbo was given a new way point south east of his most recent location to try and fly at an angle to the currents to evade any negative progress.

Nilsen & Antonio

Hey All!

Just a quick update as we head into the weekend:

This afternoon we gave Silbo a new way point to the south as we try and cut across the strong east northeast current that we are in.

HYCOM Sea Surface Height

Over the past couple days we started being drawn in towards the core of the blue cold eddy as we encountered stronger currents.  In an attempt to avoid being pulled up and back to the north, we are working on cutting back south across the strong east current of the bottom of the cold core eddy.  If we succeed, we will be within two weeks of a rendezvous just west of Madeira and we may reach the Canaries in about 5 -6 weeks.

Also this week, we ran one dive where we had the ctd on for two consecutive up and down casts so we can keep an eye on it and make sure the data is accurate as possible.  Down casts are in blue while up casts are red.

Temperature profile from surface to ~1000m collected by Silbo

Sea Water Salinity from surface to 1000m collected by Silbo

Seeing that the 4 lines are relatively close and do not show any major lags indicates the ctd is functioning correctly.  Also looking at the salinity, we can see the effects of the ‘meddies’ or salty water from the Mediterranean starting at about 700m depth.

Finally I just want to leave everyone with the big picture of the obstacles that lie ahead.  Aside from working our way through the eddies that lie between Silbo and the sunny shores of the Canaries, there are also a number of heavily trafficked areas when we start getting closer to land.  It will be crucial to keep an eye on such resources such as localizada and marine traffic’s ais data to make sure Silbo is not struck by any ships

Force Wind Sea & Honor

Nilsen & Antonio

Hey All,

So just a quick recap of the past week: Silbo has flying pretty well averaging just around 7.5 km per 7 hr stint as he made his way through the currents created by the eddy solar system.  However, over the past day and a half, there has been a significant change in scenery… The massive cold core sun has collapsed into a couple much smaller counter clockwise spinning eddies.  With this collapse, there have been a number of other changes in the regions ahead that will make the piloting a little more tricky as we try and maintain the plan we had previously of getting to Madeira.  Our main obstacle is the strong north current that is on the other side of the remnants of the sun we are working our way around.

Although we know there chances of this path staying put are pretty slim, we still hope this general flow will hold over the next month as we fly our way east towards Madeira.  Giving us a slight glimpse of optimism is that our HYCOM and MYOCEAN models are complimenting each other quite nicely: all showing that both surface and sub surface conditions are for the moment in our favor.

HYCOM Density & Currents Map

HYCOM Salinity & Currents Map

HYCOM Sea Surface Height & Currents Map

HYCOM Temperature & Currents Map

MYOCEAN Sea Surface Height Map

MYOCEAN Surface Conditions (Currents, East Component of Currents, Temperature, Salinity)

We can see in the deeper layers of the MYOCEAN data (> 600 m) the salted water tongue coming from the Mediterranean as it becomes stronger at depth. Silbo  actually encountered one of the jet/finger/filament some days ago as we can see in the currents, salinity and temperature fields at 600 800 & 1000 m.

MYOCEAN Current Fields

MYOCEAN Eastward Component of Currents

MYOCEAN Temperature

MYOCEAN Salinity

Looking ahead, the currents are turning and soon we should find a river flowing south (SE) which is shown by all the images above, so lets cross our fingers and see what happens!

Finally, I would just like to acknowledge Silbo’s most recent accomplishment of entering the VIIIIG club as he has officially flown 4,000+ km while taking on the first leg of the challenger mission.

Nilsen Strandskov, Antonio Ramos, & Oliver Ho

Hey all,

In the midst of St. Patrick’s Day, Silbo is continuing on his way on his voyage through the eddy solar system.

Our goal for this weekend and into the early part of next week is to line silbo up between the middle-right side of the green arrow shown in the image above.  The plan is to ride the sun (which has over the past couple days split from a single large eddy to two smaller ones changing the currents in our most recent position) around and to the east.  The combination of the counter clockwise spinning sun with the clock wise spinning warm eddies encircling it have created a path that will hopefully hold its form as we reach it.  We also hope this plan will raise our speed as the effects of this configuration is similar to a pitching machine for baseball/tennis etc. where the two adjacent eddies spinning in opposite directions create a super powered  current.  So as we close in, we must fasten our seat belts, cross our fingers and hold on tight as we may get a huge boost of speed over the next couple days.

For now Force Wind Sea & Honor all

Nilsen Strandskov, Antonio Ramos and Oliver Ho

Hey All!

Well Silbo is continuing on his way and now making much better progress!  Since receiving a new way point yesterday morning, Silbo has flown roughly 25 km, compared to the ~50 he flew thursday-monday.

To compliment the decision our team made when deciding on the new way point, our friend Daniel Hernández, Josep Isern, Enrique Fernández and the rest of the team from ROC-SIANI group at ULPGC provided us with a simulation that made an estimation on the progress Silbo can make with the new way point compared to the old one using a 3 day estimation of marine conditions based off of the hycom model.

This path planning simulation shows Silbo flying an average of 18 km/day with the new way point compared to 8 km/day with the old flying into the head current.

With the hope of the new way point working as well as the simulation predicts, we hope to now ‘surf’ the large cold core sun eddy to the south around and to the east and use the smaller warm core planet eddies to head east towards Madeira.

Silbo’s projected path through the solar system of eddies to the south

The path highlighted in the image above provides silbo with a well beaten trail of currents that lands him pretty close to the western shores of Madeira where our friends at PLOCAN hope to deploy some drifters along with conducting an inspection of the glider and providing any support that may be needed.  Given that Silbo can maintain the speed estimated in the simulation of 18km/day, he would reach that point in roughly 6 weeks.

Unfortunately this would only hold true if these conditions remained the same.  The ocean is one of the most rapidly changing environments on the planet and so silbo will need to keep up a good pace while the teams in the Canary Islands,   TWR, and here at Rutgers continue to keep an eye on the most advantageous way points and flight patterns to make sure we stay in the best currents.  Since March 8th when Silbo was deployed, the large warm core eddy that we are on the outer edge of has migrated about 55 km to the south east.

Unfortunately, I do not have as accurate of a reference point as with this eddy as it started out with its center near Santa Maria for others, but they have noticeably moved as well.  An example being the warm core eddy planet south of the cold sun has been edging further north.  Seeing this, we must do our best to watch how these eddies are moving and try and aim silbo not only with how the currents are being shown, but with some insight on how they may shift in the near future.

Nilsen & Antonio

Hey All!

Well Silbo has been back in the water now for over 4 days now, and although he has been making steady progress, it has been quite slow, however we are moving further away from the island traffic which is becoming less of a threat.

Ship Traffic for March 11

With the way point set on Madeira, we have been at the will of a strong head current that is the product of the strong clockwise spinning warm eddy to our north and another to the east combined with the large counterclockwise spinning cold eddy to our south.  These eddies are shown below in the three road maps we are using: HYCOM, NLOM/NCOM, and MYOCEAN.

HYCOM Sea Surface Height and Currents for March 11

NLOM SSH and NCOM Currents for March 11

MYOCEAN 96 hour averaged forecast of SSH and Currents

The first two images of the hycom and nlom/ncom models both show the solar systems of eddies that are the cause of Silbo’s strong head current.  The third image from myocean is a 96 hr futurecast of the sea surface height and currents conditions that shows the persistence and strength of eddies over the next three days.

The eddies have even caused similar patterns in the salinity, temperature and density seen here in the hycom imagery:

HYCOM density for March 11

HYCOM Salinity for March 11

HYCOM Temperature for March 11

Similarly, Antonio has provided us with the MYOCEAN forecast for the salinity at 1000m.

MYOCEAN Salinity for 1000m

At 1000m depth, we see a number of ‘meddies’ or eddies produced from the introduction of super saline water of the Mediterranean colliding with the fresher water of the North Atlantic.  These will be important to keep an eye on for piloting as we may try experiments of flying between 500-1000m to avoid unfavorable currents closer to the surface.

For now, we agree that the best course of action is to change the waypoint to the south to try and get out of this strong head current and to move our way through the solar system of eddies to best continue on our way to the Canaries

New proposed way point of 34 N 23 W

Force Wind Sea and Honor

Nilsen, Antonio & Oliver