
Monday, April 28, 2008
A Weekend Storm

Friday, April 25, 2008
Flight Tests

The deep basin off Halifax turned out to be an excellent test bed. Water over 100 m deep that is so close to shore. So we took advantage of the natural topography on the way in.
We are now half way between HL3 and HL2. We moved the HL2 waypoint a bit to the northeast so that it is in between the shipping lanes.
RU15 is now set to just bounce back and forth between the point between the shipping lanes and HL3. We'll keep this pattern going for several days.
We'll keep one eye on the battery and the other on the weather. Scott & Marlon have all the equipment for recovery and a boat ready when its needed.

Monday, April 21, 2008
Progress Along the Halifax Line


Currents remain low, 5 to 20 cm/sec.


Friday, April 18, 2008
Last Leg

Batteries still looking good, as far as you can tell. Time to settle into a scientific sampling section to go with the shipboard data currently being collected.

4.74 km to the Halifax Line

RU15 just surfaced 4.74 km away from HL5, the outermost shelf point on the Halifax line. We should be there sometime later this morning. At that point we'll make the turn in. Mostly clouds in the imagery this morning,
so we'll see how that develops. Currents have remained low, so its not as critical as it was in the Gulf Stream region.


Once we hit HL5 and make the turn, we'll start a new section on the webpage and configure things for a standard cross-shelf line. There is a shipboard cruise going on right now, so we hope to contrinbute some scientific data to that project on the way in. A new area for us, but we benefit from a lot of local knowledge up in Halifax. Thanks again to all up there for sending their help to bring this thing in.
Tuesday, April 15, 2008
Eastward to the Halifax Line

This Satellite Sea Surface Temperature Image pretty much sums it all up. Last week RU15 followed the narrow band of warm water northward up to the deep side of the shelf break. Note that while it was in deep water, the track of RU15 has that serrated knife edge look to it characteristic of the presence of inertial waves. A look back at current vectors from John's time series plots shows the expected rotation of the velocity vector.
RU15 then successfully crossed the shelf break over the weekend, and went far enough onto the shelf to pull out of the currents that were heading southward, back across. Currents remained low Sunday and Monday, as we continued northeast. With good progress being made, we switched our target on the Halifax Line to HFX5, the outermost point that is still on the shelf. From HFX5 we'll turn to the northwest and follow the Halifax line in. Estimated time to Halifax is about 12 days.
Once we reach HFX5, we'll start up a new x-section plot on the webpage. That should happen sometime thursday or friday.
Once we reach HFX5, we'll start up a new x-section plot on the webpage. That should happen sometime thursday or friday.

Back home in New Jersey, RU05 left Massachusetts on April 3. RU05 should be hitting the offshore side of the Tuckerton Endurance Line about the same time as Ru15 hits the Halifax line.
We also have two more glider deployments scheduled for Tuckerton. If all goes as planned, by the end of this week, you should be seeing RU15 inbound on Halifax Line, RU05 inbound on the Tuckerton line, and RUo7 & RU20 outbound from Tuckerton. All from the comfort of your web-browser.
Sunday, April 13, 2008
A Quiet night on the Scotian Shelf

A test version put together over the weekend is above.
You need to load it and something like double click on it to get it to zoom in to the "curly" vector forecast currents. Based on where the glider is now, the forecast says currents are to the southeast and low. The glider is reporting low currents more to the south. This could end up being a very useful tool with comparisons in this general agreement. We'll work more on this forecast product visualization on monday. It also sounds like Marlon is finding some relevant Canadian forecasts we can start looking at.

We are back to full water column sampling. The above section starts when we left the Gulf Stream Ring and started crossing the slope water. Most recent data is on the right. Surface temperatures are running about 2C. We want to head northeast into the water with 4C surface temperatures. RU15 has been on quite a journey. In the Gulf Stream we were looking at the differences between 22C in the Stream, 18C in the ring, and now we care about 2C versus 4C.
Saturday, April 12, 2008
Crossing the Shelf Break - A Friday Night Course Change

Dave changed the waypoint from straight east to straight north, and we switched to a stay deep behavior to avoid the stronger surface currents, flying between a depth of 30 m and 100 m. By morning we had crossed most of the shelf and were getting into slower currents.

Here's the plot of current speed and direction during the crossing. Lots of strong currents to the west on 4/11 that caused the problem. But as soon as we crossed, currents turned to southeast and tried to push us back off the shelf. The good news - at least it had an easterly component.

Here is a zoom in on the track. Our attempt to fly east did nothing but cause the small loop in the track just offshore the shelf break. We gave up on that and jumped across. Now that we are on the shallow side of the shelfbreak, we are heading northeast, towards the Halifax line and the favorable currents identifed by Scott & Marlon in the previous post. We are back to full water column sampling.
We have a much more restful night ahead of us.
The Approach to Halifax




to the north along latitude 62W. South or Halifax, the very cold water (pink, 2C) is extending far offshore.
All this indicates that an approach to Halifax from the south would run into a steady headwind for nearly the entire crossing. It is better to work our way eastward into the relatively warmer (4C), and Chlorophyll free water, and approach Halifax from the southeast. We just changed the waypoint of RU15 to fly to the northeast into the favorable currents so nicely identified by our friends in Canada. Thanks Marlon & Scott.
Friday, April 11, 2008
Tuesday, April 8, 2008
Favorable currents & a lucky break



A lucky break in the clouds. The only clear area offshore is right over RU15.

As we approach the shelf break this week, we'll be changing the scales on several of our plots to make them easier to read. Temperature and current scales will be adjusted for the smaller range. The SST Zoom has been zoomed even more. We'll restart the temperature sections so we can see the smaller scale fronts of the shelf.
Monday, April 7, 2008
On to the Next Eddy

Saturday, April 5, 2008
The Route to the Shelf Break


Thursday, April 3, 2008
Warm Current Loop Right off NJ Shelf
A close call with a Gulf Stream meander

But then as soon as we were north of the meander crest, we had to apply the brakes. If we stayed in the fast swirl velocity, we would have been swept by the small eddy near 41 N, 64 W. If we missed the free ride from the small eddy, we'd have to fight against a cold headwind to get to the north. So we turned the glider perpendicular to the swirl velocity and started flying back out. We kept changing the waypoint to stay perpendicular to the swirl velocity, just as if you were swiming perpendicular to the rip current. This time around we were close enough to the edge to get out of the warm ring just in time to end up on the south side of that small eddy centered near 41 N, 64 W. We found the cold water that is being swirled around, and turned to the west to start following it around the new eddy. We'll conitune to swirl around this eddy till we get around to the northeast side, probably sometime saturday. Then we'll exit this eddy, jump back into the cold water and follow it to the northeast up to the next eddy up we saw up around 42N, 63W. We'll keep flying eddy to eddy till we make the shelf break. We can worry about most of that over the weekend. Cause tonight, we rest. RU15 is in the small eddy, riding some slow but favorable currents. We'll all get some sleep and check it out in the morning. Our robot is fine - for now.
RU15 enters the small eddy

Wednesday, April 2, 2008
Student Links
Marlon, Scott McL., John C., and other friends in Halifax ------
We have a class of undergrads here at Rutgers that is just having a great time with this. They are scouring the web for datasets, satellite images, model forecasts, altimeter maps, ice maps, wave forecasts, etc, etc. Some are working on the path planning. Others on the conditions in the landing zone. Just like the Stommel race, but this time the race is against the clock. Dave Aragon, our glider electronics tech, has given us 35 more days of flight time (starting today) before we have to hang it up. We think he's built in a safety factor, but he's certainly too smart to tell us what it is.
So RU15 has to stop surfing the Gulf Stream and looping around in the warm core rings and head for a home port. Do you have a similar group of students that we could set up a skype or other video conference with?
Our students would like to talk to yours about the sea conditions, ice conditions, currents, weather, and everything else that comes up when you are searching for a home port. I-COOL edu at its best.
We keep seeing the wave forecasts calling for 7 to 13 foot seas offshore of Halifax. You know from the HyCODE days that waves like that are not something we are used to. Maybe with your help we can bring this glider home and snag a Dalhousie sticker for the hull in the process.
Hope to see you all in a few weeks!
We have a class of undergrads here at Rutgers that is just having a great time with this. They are scouring the web for datasets, satellite images, model forecasts, altimeter maps, ice maps, wave forecasts, etc, etc. Some are working on the path planning. Others on the conditions in the landing zone. Just like the Stommel race, but this time the race is against the clock. Dave Aragon, our glider electronics tech, has given us 35 more days of flight time (starting today) before we have to hang it up. We think he's built in a safety factor, but he's certainly too smart to tell us what it is.
So RU15 has to stop surfing the Gulf Stream and looping around in the warm core rings and head for a home port. Do you have a similar group of students that we could set up a skype or other video conference with?
Our students would like to talk to yours about the sea conditions, ice conditions, currents, weather, and everything else that comes up when you are searching for a home port. I-COOL edu at its best.
We keep seeing the wave forecasts calling for 7 to 13 foot seas offshore of Halifax. You know from the HyCODE days that waves like that are not something we are used to. Maybe with your help we can bring this glider home and snag a Dalhousie sticker for the hull in the process.
Hope to see you all in a few weeks!
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