CFCC Deploys 2 Drifters Off NC Coast

Jacqui and I have been working on ways to incorporate the tracks of the drifters into the program and coming up with some great ideas.

I just sent out a P.O. to purchase 2 more transmitters and around 2000 transmissions, so next year we will be ready!

 

 

Pictures are out of order. Will do better on second post!

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Drifter Newsletter #2

October 2009

Urethane Foam

There has been some discussion about what  “2-part marine urethane foam” to use when filling the PVC pipe. While SMCC suggests “Poly-U-Foam” (available on line for about $40/quart), there are probably other types in smaller qquantities that will do the job.  US Composites sells a “4-lb kit” for about $20 (catalog # “FOAM-0204”).  In fact, as Jason Hyatt (Mass Maritime) suggest, we MAY be able to get by with a can of “Great Stuff” from your local hardware but we do not know yet how well this will hold up in seawater.  Note that we did not use any foam at all for the first few years we deployed drifters. We only added this extra buoyancy within the pipe in hopes that the transmitter stays afloat  despite the inevitable loss of the other flotation.

MATE Drifter Blog

Thanks to our colleagues at MATE, you can follow a blog of drifter experiences at: http://coseenow.net/mate/ .  To make an entry in the blog, click on the “Register” link , “Log in”, and blog away. Note that they already have a set of “categories” to choose from including, for example, “curriculum development”, “collaborating with scientists”, etc. Under the “resources” page, there is a link back to the various SMCC/GoMLF/NOAA effort. I plan to enter this newsletter in their “Tracking the Drifter” blog.

Drifter Photos

We have compiled a gallery of drifter photos (linked from the bottom of the “drifter construction and technology” document at http://www.nefsc.noaa.gov/drifter/ ) and may harvest some more from the blog. Please send your contributions to james.manning@noaa.gov (or upload them to the blog) and supply the photographer’s name so that we can give the proper credit.

Tracks of the Month

There are always particular tracks that stands out from the rest. This month, the Cape Fear Community College drifters have provided some interesting tracks.  Their first drifter that was deployed just a few weeks ago has traveled over 2000 kilometers in the Gulf Stream but, even more amazing,   their 2nd drifter traveled over  hundred kilometers in one direction, turned around and came directly back nearly to where it started. CFCC is now working on building more drifters and some of the students are designing a wooden (ie biodegradable) drifter!

New Drifter Designs

Two new-style drifters will be deployed within the next few weeks. One is the “Kathleen” bucket drifter  which will track the very-near surface waters of the Merrimack River Plume for Dr. Dan McDonald of UMASS Dartmouth. Many of these units have powerful strobes, Garmin receivers, temperature and salinity sensors installed along with the TrackPacks.  There will be a total of 27 units deployed at the river mouth during an outgoing tide after a large runoff event. Stay tuned.

The other new style drifter, developed recently by Ruben Davis of  DatisSystems of N. Falmouth, MA, eliminates the need for satellite transmissions by implementing a radio-based system for near-shore high resolution applications. Stay tuned for the result of these prototypes.

TrackStick GPS receiver

Jason Goldstein and Win Watson (UNH) have come across the TrackStick.  Google this and you will see a compact device that may be a nice alternative to the Garmin units (for internal storage of fixes) and apparently provides more battery life.

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A Drifter Lab Exercise

Our Vice president of Academic Affairs asked me the other day if the tsunami affected the motion of the drifters here in Monterey Bay. “Voile!” I thought, what a great idea for a lab. If our vice president thinks that the tsunami might have affected the drifters, then our students must have the same question. So I developed the lab linked below.

I developed the lab to generate interest in the motion of the drifters. My students started on this lab on Monday and will finish it today. What I’m realizing is that perhaps the main benefit will be that in order to understand why the tsunami did not affect the motion of the drifters, the students will have to internalize how waves move about in the ocean, that it is not the flow of water parcels, but rather the water parcels interacting with each other to cause a wave. Ships out at sea are not affected by tsunamis, and neither are our drifters.

A Word format of the lab is available here:
http://www.mpcfaculty.net/alfred_hochstaedter/ocean/lab/DrifterTsunami.doc

 It is also available on the MPC Oceanography website:
http://www.mpcfaculty.net/alfred_hochstaedter/oceanography.htm

-Fred

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Ever Feel Like You’re Just Drifting in Circles


The MPC Drifters are back in the water this week as our MBARI collaboration continues for a second week. The data on the image above represents about 27 hours of data, from the afternoon of October 5 to about 6 pm local time of October 6. It illustrates quite nicely the 24-hour periodicity that is evident in much of our data. We have semi-diurnal tides here on the coast of California, so that pattern is not tidal. The drifters tend to have a stronger SE component of motion in the afternoons and a stronger NW component of motion in the early morning hours.

I’m trying to get some images of students deploying and retrieving the drifters. I’ll post them as soon as I get them.

-Fred

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MPC Drifters Retrieved!

A couple of MPC Oceanography students accompanied the MBARI team to recover the drifters yesterday. They quickly found both of them and brought them back on board. They were out for almost exactly 48 hours. After drifting south for the first 12 hours or so, perhaps due to strong NW winds that day, they turned and drifted north and west, along the expected counterclockwise rotation of surface water in Monterey Bay.

Here is a quick and dirty cut and paste job of their complete paths. I don’t have the software set up yet to make my own maps of their paths. These are from the AeroStar tracking website. They generally drifted from southeast to northwest.

We’re very happy with this first deployment of the drifters and thank the MBARI team of John Ryan and Erick Rienecker. The MPC students seemed to enjoy it as well. Four of the five we sent came back very enthused about the whole experience. They took some pictures, but I haven’t been able to get their pics downloaded onto my computer. Maybe we’ll see some next week.

So I’m thinking about how to integrate this stuff into my lesson plans for next week. I’m thinking of creating a short activity where we ask the question, “Did the tsunami affect the movement of the drifters?” This will involve the following aspects of data manipulation:

  • Determining the time the Tsunami hit Monterey
  • Making a hypothesis about whether or not the tsunami affected the drift
  • Identifying exactly what we would see, and on what timescale, if the tsunami affected motion.
  • Manipulating the Aerostar tracking site to find times and positions of data points
  • Looking at the data to determine if the identified changes in motion did or did not take place.

The anticipated outcome is that the tsunami did not, in fact, influence the movement of the drifters. Hopefully, this will be a useful realization that wave motion and current motion can be totally different because they are totally different processes. We know, for example, in the northeastern part of Monterey Bay that the longshore drift of the sand on the beaches is in exactly the opposite direction (west and southwest towards Moss Landing) than the surface currents (north and west, as our drifters demonstrated). So it would follow that tsunami motion would not necessarily be detected, especially at the temporal resolution available to the drifters (one measurement every half hour).

I’ll share this if I get it going.

Over and out.

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Serendipity Strikes the Drifter Project

Sometimes it seems like articles in newspapers are published as if they were planned to coincide with my syllabus. This was one such week. We set the drifters adrift on Tuesday and only two days earlier, on Sunday, the New York Times published a piece on surface currents in Monterey Bay, Finding Order in the Apparent Chaos of Currents.

The story has a big flashy graphic that decorated most of the cover of the Sunday Science section of the Times, and comes complete with an accompanying flash video and podcast. Click image for a larger, more readable version.

The article reveals how theoretical scientists are doing some pretty wild stuff with Lagrangian flow models and “Lagrangian coherent structures”. Now, I can barely pronounce “Langrangian”, much less explain it to my students, but there are fascinating revelations in all kinds of fields such as blood flow from ventricles, turbulence in atmospheric flow patterns, and, of course, dispersal of pollutants in the ocean currents.  On this image, the bright colors show the “amount of stretching and chaotic stirring in surface water”. I’m OK with the chaotic stirring, but stretching? Every semester I explain to my oceanography class about the incompressibility of water is the basis of hydraulic brakes working properly. Now I have to explain that water gets stretched somehow? Maybe now that you have taken the time to read this can explain this one to me.

 In any case, the article is very cool, even though I still don’t get a real, physical feel for how water circulates through the bay. It’s a different way of looking at flow with which I have no experience.

 I haven’t decided yet whether to ask my students to read this article. What do you think?

 Drifters come out of the bay today. More on that later.

 -Fred

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Drifters survive a tsunami on their maiden voyage


This is what the path of one of the drifters looks like today, approximately 24 hours after deployment. Remember yesterday, the drifter was taking a southerly route. Today, the drifters have turned northwards. Today is not as windy as yesterday.


This is what the other drifter path looks like today. It has also turned north after drifting south the first day. This one may have drifted further south the first day because it was deployed closer to the Salinas Valley, where the onshore winds are strongest. Well, maybe.


Here’s what the winds look like today. You can definitely see that the wind speeds are lower today, especially in the northeast portion of the bay where the drifters were deployed.

We had a bit of a distraction today with the Samoan earthquake and tsunami. The tsunami made it all the way to Monterey by yesterday evening, although its amplitude was only a few centimeters by the time it made it here.


In the image above (click on it for a larger image), you can see that the tsunami entered Monterey Bay at just past 0400 on Day 273, which is Sept 30, 2009. I guess we can say that the drifters survived a tsunami on their maiden voyage.

I just got word from the MBARI guys that the drifters will be recovered tomorrow. We’ll be sending a few more students on the cruise with them.

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The drifters are adrift here in Monterey Bay

Well, the drifters are adrift here in Monterey Bay. They were deployed mid day today, local time by a team from the Monterey Bay Aquarium Research Institute (MBARI) and three Oceanography students from Monterey Peninsula College. The study is part of an intensive effort to look at the physical oceanography associated with harmful algal blooms (HABs) After four messages to the satellite (configured at 48/day), the image looks like this:

 You can see two drifters are out there; the single position is from when the ship was on the way to deployment. Both of the drifters are drifting south or southeast. This is somewhat unexpected as we thought the circulation in Monterey Bay was counterclockwise as I explained in my previous blog.

Wonder why the drifters are drifting southsouthwest? They are moving directly towards the Salinas Valley, probably as a result of seabreezes that pick up every afternoon here. At least that’s my current (ha ha) hypothesis. The winds today are shown on the image above, blowing straight towards the Salinas Valley, which is between Moss Landing and Del Monte Beach on the image above. The drifters were deployed northeast of Moss Landing, somewhat north of the MO buoy as shown on the image above.

 Follow along at the usual spots. I’ll share the response of the students in a later installment.

 Over and out for now,

 -Fred

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Getting Started at Monterey Peninsula College

Greetings from the Central Coast of California. This is my first attempt at blogging, so I hope I do it right. From what I’ve read on other blogs, I think I’m supposed to record my stream of consciousness and try to stay somewhat on topic. We’ll see how that goes.

In an effort to kick-start our drifter program out here on the shores of Monterey Bay, I went and visited Jeff Paduan at the Naval Postgraduate School. Jeff had to put me on a special list just to allow me to walk onto the grounds of NPS. Jeff is the local HF radar guru and has written papers on the circulation of Monterey Bay. Jeff is PI for the Central California component of the Coastal Ocean Currents Monitoring Program, perhaps better known as COCMP. The COCMP website has a nice pdf brochure imaginatively entitled the COCMP Reference Guide (How Ocean Current Mapping Works and How it is Useful) (image at right). It has some nice information that would be useful for teaching students how the HF radar works as well as beautiful color photographs of HF radar antennas in some of the most stunningly picturesque locations in the world. Strangely enough, the best images of Jeff’s HF radar ocean current data are at his Central California Currents page. Here’s what the currents look like for today in our area:

Those circular patterns you see in Monterey Bay on the image on the right are not tidal. They have a 24 hour periodicity and form in response to offshore and onshore breezes that cycle back and forth throughout the day.

Jeff and I talked quite a while about HF radar and I learned quite a bit. I still can’t explain all the intricacies of which frequencies they use to get the best Doppler Effect and why, but at least my eyes won’t roll too far back in my head next time we go through it.

We also talked about “typical” ocean circulation patterns in Monterey Bay. The image below is from one day back in 1994—exaclty 15 years ago from our drifters workshop.

The image shows ocean currents layered over sea surface temperatures. It shows the typical counterclockwise circulation in the bay and the clockwise eddy just outside the bay. As was true on this day in 1994, the northeast portion of the bay is the warmest, and this water is pulled out into deeper water by the currents.

I looked at some of the drifters that Jeff uses in his research. They’re commercially made by Pacific Gyre. They have a floating sphere that contains the transmitter and then a sail system that opens up like an umbrella.

The next stop in my tour of ocean current researchers was the world famous MBARI, the Monterey Bay Aquarium Research Institute, to visit Erich Rienecker and John Ryan. Erich is one of the marine technicians and John is a researcher specializing in phytoplankton blooms. Here’s John and I looking at some eye-popping data on John’s computer. I was just blinking, I swear.

Here’s that eye-popping data John and I were looking at:

The left image shows satellite-generated data for chlorophyll in the water, whereas the right image shows sea surface temperatures. Clearly there are other factors besides just temperatures driving the magnitude of plankton concentrations.

The last week in September and the first week in October, John and Erich will be involved with an intensive data gathering effort in this area involving satellites, AUVs, moorings, and………..drum roll please……… OUR DRIFTERS!

On Monday September 28 and Monday October 2 we’ll send students out on their cruises to deploy our drifters and launch their AUVs among other tasks for this study. Later in the week, we’ll send students out with them to try and retrieve the drifters. Should be fun, and a great experience for the students.

Back in the classroom, we’ll be following the progress of the drifters on the computers. Hopefully this will set the stage for increased interest in learning about atmospheric circulation and ocean currents. Then, in early November, we’ll take the whole class out on a cruise and release one of the drifters once again (assuming all goes well with the MBARI guys).

Over and out,

-Fred

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Drifter Newsletter #1

Sept 2009

Newsletter plan
This is the first of what I imagine to be a nearmonthly “newsletter” on drifter issues. Now that there are a few dozen labs using the SMCC/eMOLT drifters, we should probably try to compile our notes. If you have anything you would like to share with others (photos, funny stories, bad experiences, etc), please send it along to james.manning@noaa.gov. Keep in mind that most of the information regarding the drifters is now linked from the realtime website http://www.nefsc.noaa.gov/drifter but these periodic newsletters will provide your information on “what’s new”. If you want to be removed from the mailing list or you want some of your colleagues to be added, let me know.  This first issue is going out to all users that have deployed, or plan to deploy, this fall.

Check transmissions for a day or two before deployment
Given that the transmitter technology is constantly evolving and not all of these units work flawlessly, it is a good idea to set your transmitter outside the day before you deploy it under a clear sky view to make sure you are getting good fixes.

Set transmitters outdoors after shutting them off to verify they are indeed off.
Those of you who were at the workshop in August should put your transmitters outdoors to make sure they were properly turned off. There was at least one case where the transmitter was left on which probably resulted in a 2030% battery loss. A transmitter makes 3 attempts to get a fix with each sampling period so, if it is hidden from the satellite, the battery will run down 3times faster.

Watch for fiberglass rods wearing due to buoy stick chaffing
We recovered several fiberglass rods this summer which, after having been at sea for a multiple weeks, were worn down at the point of contact with the plastic buoy stick. This might have been due to the holes in the buoy sticks being two small so that they didn’t swing easily with wave movement.

Refrain from enabling the “advanced configuration” motion sensor
After experimenting with the this function on a couple units attached to my bicycle, I found that it didn’t work as it was suppose to. So, we may need to wait for another generation of transmitters before implementing this setting. We have however made use of the advanced configuration in order to get
“48 samples per day”.

Hoseclamps vs cable tie transmitter mounts
In our quest to minimize the cost of drifters, we recently started using heavy cable ties to secure the transmitters (where we used stainless hose clamps in the past). Last month, there was at least one documented case of the cable tie breaking. While this may have been due to the unit crashing on the rocks, it is worth noting nevertheless. If you experience any faults like this, PLEASE let us know.

Marine Advanced Technology Education (MATE) deployments
We are very excited to have expanded the use of these drifters around the country thanks to a NSF funded workshop in August where nine schools each went home with two drifters. As noted on the realtime site, UMaine Machias and Cape Fear CC, for example, have already made deployments.

Documenting your deployments
One of the links under the realtime website allows you to document your deployment. Based on the information you enter it is suppose to give you the “deployment ID”. If you want to know this deployment ID BEFORE you deploy, see the “deployment ID convention” link that is under the “construction and technology” notes. Please keep in mind that these websites are constantly under development in our attempts to automate things as much as possible.

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