Archive for May, 2008

Good Night Scarlet Knight

Saturday, May 31st, 2008

RU17 enters the warmest waters of the Gulf Stream in the early morning (GMT) hours of June 1.

Currents are picking up, reaching 80 cm/sec, running towards the northeast.  RU17 is heading southeast, perpendicular to the drift to get deeper into the Stream overnight.

The google earth view below. That northern part of that large warm filament that appeared in Tallinn on thursday is almost entirely gone.  The southern part is just sitting there.  We hit the good side of this event.

We are done for the night.  RU17 position and health checked, the CTD was turned on. For those of you still up, you can follow along by checking the web links on the right and clicking on Atlantic Glider Track w/SST.  RU17 should be back at the surface at 1 am local and 5 am local (east coast) time.  It's only instructions are to download the new CTD data and continue swiming deeper into the Gulf Stream.  We'll move the waypoint during the 9 am surfacing and turn the CTD back off. 

Good work by all.  We are in the Stream. 

Back to the Big Picture

Saturday, May 31st, 2008

So why am I here blogging on a saturday night? RU17 is due to surface in less than an hour, and is just about to enter the Gulf Stream. Its a major transition in how we fly. Also, its just really cool to watch.  This is only our second time to fly into the Stream, so it still carries with it an awesome sense of accomplishment.  Especially after we had to cross the Slope Sea without the aid of a major warm core ring.  Should we have waited for the large meander near 70W to break off and propogate westward to the shelf break?  We could have our destination was again Halifax.  But we couldn't wait.  We need to get far to the east before the stormy weather of winter sets in.  So we had to go as soon as we were ready, and live with whatever conditions the ocean gave us.

Below is a snapshot of those conditions downstream.  Once we get into the Stream near 71W, we'll rind down the eastern side of that meander crest and try to beat the warm ring formation. After that we have two gentle meanders with crests near 64W and 60 W to follow.  Then there is the warm ring formation event we see going on now at 57W.  Hopefully this event is complete by the time we get there so we can go straight across than all the way around.

After that we zoom out to the North Atlantic farfield.  Here the big transition occurs at 50 W. West of 50W, there is a lot of cold water of Titantic fame extending far to the south to about 40 N.  East of 50W, you see the Gulf Stream Extension Region, and the bifurcation of the warm currents.  Some of the warm water heads northeast to about 50 N, 40W.   Some of it heads straight across towards Spain.  If we get that far, we are shooting for the southern route that goes straight across.  One of the main reasons is simply to keep the batteries as warm as possible for as long as possible.  Cold batteries die faster.



May 31 2008

Saturday, May 31st, 2008

Gliders are flying well.  We also welcome the wider NRL biospace community. RU05 continues its cross shore line and is holding position even though it is encountering strong currents.  Luckily, the transect is following the beachgoers golden rule by flying along and not against te currents.  The is a particle layer found right below the pycnocline across the transect and in the nearshore waters there is a nepheloid layer.

RU16 is roving back and forth in Monterey Bay.  Backscatter and chlorophyll fluorescence appear to correlated with concetration highest above the thermocline.

Racing the Ring Formation

Saturday, May 31st, 2008

The satellite-derived Sea Surface Temperature (SST) maps have been modifed to now enhance the structures within the Gulf Stream.  The crest of the S-Shaped  meander system is clearly now enhanced.  The structure is on its way to pinching off to form a new Warm Core Ring that will be centered about 38 N, 70 W.  We need to get deep into the Gulf Stream and shoot quicky downstream to beat the ring formation process.   But deep into the Gulf Stream makes it hard to get out if we get caught in a new warm ring. The ring will be pretty big, about twice as big as New Jersey, so its a lot of distance to cover if we need to swim out. We need to get past about 68W to keep from getting spun around like we did on the flight to Halifax.  

Below is the new zoom in on RU17 as it enters the Gulf Stream.  The warm filament continues to diminish in size in this image.  Currents are to the northeast.  We set the waypoint (X) to the east and deep in the Gulf Stream.  We will continue spinnig around this point over the next 24 hours.

Current speeds below are increasing.  Up to 60 cm/sec.  We want to get these well over 100 cm/sec over the next day.

An Overnight Approach to the Gulf Stream

Saturday, May 31st, 2008

Below is the early morning image from May 31.  RU17 whipped around with the eddy and approached the Gulf Stream overnight. Currents where to the northeast, and increasing.  We kept RU17 on a perpendicular course, heading to the southeast, using the glider velocity to get us into the Gulf Stream. 

Currents are increasing above the glider speed (the dotted red line).  When currents are above the red line, we behave more like a drifter. Below the read line, we are more like a boat. 

With the 9 am surfacing this morning we switched to a new mode of flying. We are now focused on using the glider velocity to get us into and keep us in the strong currents.  We'll also switch the enhancements on the satellite images that appear on the google earth plots and the "Atlantic Glider Track w/SST" COOL Web Links on the right.

Approaching the Big Warm Filament

Friday, May 30th, 2008

Below image shows the S-shaped Meander system (red colors around 24C) and how RU17 is approaching the Gulf Stream.

Zoom in on the glider and it is just at the edge, hitting the 20C isotherm. The gap seperating the large warm filament that we found yesterday in Tallinn when the clouds cleared appears to be narrowing.  A more traditional warm filament is forming in the dark red waters about 24C. Here the filaments start small and tend to grow opposite the main flow with time.

The fast kick to the north on 5/29 certainly helped our cause.  Now we are getting currents to the northeast, a good sign as we try to enter the Gulf Stream.

Last time CTD was turned on (early today), temperatures where about 17 C.  We should start to see these increase as we cross the big warm filament.  We'll keep an eye on this as we cross.  Its not the traditional warm filament that forms as a near surface feature, so we are not sure how deep to this feature will turn out to be.


A Happy Welcome Home

Friday, May 30th, 2008

After sending RU17 on its way around the eddy Lisa found in the previous entry, we walked around Tallinn. Eventually we were left with two hours to kill waiting for our plane.  Harvey Seim, a University of North Carolina partner in our Mid-Atlantic Coastal Ocean Observing System,  suggested a walk up the hill to the castle walls at the top for the best views of the city and the port.  The city was amazing - buildings dating back hundreds of years and, as advertised, the east meets west architecture.

We ended the trip with a quick meal at the Burrito Bus with some new found friends from Estonia, and a cab to the airport.

The image below is what we found when we landed in the U.S.  We spun around the eddy with the strong currents to the north, following that finger of slighty warmer water as it curved around to the northeast.

Amazing how a making some distance over the ground can change the mood in the operations center.  We left Rutgers early in the week with RU17 flying into head-currents, as we zig-zagged through a complex field of eddies and filaments. We returned with some serious kilometers being clocked, and smiles all around.

Lisa finds an eddy

Friday, May 30th, 2008

We were just finishing up the US-EU Baltic 2008 International Symposium at Tallinn, Estonia yesterday.  John gave us a call during the last speaker.  RU17 was encountering a current to the west, and we needed to go east into the Stream.  Satellite imagey had just cleared and revealed the new warm filament.  So we had to make a decision, we could not continue flying east.  So do we turn northeast or southeast.  Lisa enhanced the most recent satellite image and posted on the blog web links on the right.  We picked it up in Estonia, and found that RU17 was in a very small eddy off the western side of the new filament (see black oval below).  The decision was made.  Fly to the northeast, and follow the eddy around.  John gave it the new waypoints, and we headed off for an evening of team building with our NOAA & Navy partners, and scientists from around the Baltic.  John found us later that night with another phone call.  RU17 was whipping around the eddy, increasing its speed, and making up for the time we lost in the westerly currents over Memorial Day weekend.  We are back up to the average speed we need of about 1 km/hour to get through this phase of the deployment and not exceed our quota of battery time.


May 29 2008 again

Thursday, May 29th, 2008

Since the earlier post in the day we have had some nice updates from our partners at NRL and Cal-Poly. Based on the early post today, I got this update from Igor.

It seems conditions are changing to upwelling again. COAMPS predicts upwelling and M1 currents are starting to go south again. So ru5 will sample upstream of upwelling and ru16 will sample cross -shore variability of transition to upwelling and development of the the southward flow. Remus will sample bio-optical-physical process in the "shadow" and in the Bay during transition to and development of upwelling. It might be interesting.

"Mark chimed in after his morning here at Scripps at the OOI CI meeting.
Hi all,I agree with igor's assessment of current conditions. I flew over monterey bay today and the nw winds were creating significant white caps and setting up an upwelling senario.
Sent from my Verizon Wireless BlackBerry"
So strap in and lets crank up a large diatom bloom. Lets watch the ocean color get up up to 2.3785 inverse meters (my prediction in the nearshore zones), and lets get Igor an optical closure, and with subsequent export flux deplete some deep water oxygen!!!

Finding the Gulf Stream in the Old Days

Thursday, May 29th, 2008

Well Scarlett Knight is slowly trying to get to stream. The we will try to get the glider to remain in the stream as long as possible! But as we enter the Gulf Stream it is great to look back to the giants before us. While Ben Franklin was acknowledged to have mapped the stream, scientific focus on mapping the stream to understand its dynamics was a major focus in the 1950's and 1960's. In June 1950, the synoptic path between Cape hatteras and the Grand Banks of Nefoundland was mapped by Fuglister and Worthington. He is pictured with some oceanographic giants (pictured are Worthington, Bumpus, Fuglister and Riley). The efforts to map the Stream was very labor intensive, requiring many ships, many people, opertating under very rough conditions.

Given this, there was much effort to improve technology to make life better. Simple advances were invaluable!! For example, one classic paper in the 1960's showed that using a towed thermometer looking at the temperature changes at 200 m depth could track the Gulf Stream. The scientists could then use the data to adjust where the ship was moved, and this allowed them studied the spatial variability in this undulating Gulf Stream. The glider by virtue of its undulating behavior represents the next generation of this approach. The BIG advantage is that now instead of going to sea i get to sit now in really exciting committee meetings, fill out lots of progress reports, and answer my phone...... wait a minute, maybe the new future has some downsides........