Archive | Tracking the Drifter

The Slow Death of CR’s Drifter

It appears that College of the Redwoods’ drifter is slowly dying. NOAA’s drifter guru, Jim Manning, feels that the drifter’s flotation may have been damaged. The drifter is probably partially submerged and is no longer transmitting its location. It has been over a week since its last transmission, about 75 miles offshore from San Luis Obispo.

Then, miraculously, the drifter reported its position WNW of San Diego the day before yesterday (! Perhaps a fortuitous wave tipped the GPS unit out of the water for a moment at the precise instance of a position burst.  The drifter may still be in the game! Unfortunately it is unclear if, or when, it may transmit its location again. In any event, Mexican waters appear to be next on the itinerary.


Insights into a Mystery

After 28 days adrift, College of the Redwoods’ drifter is poised to reveal some insights into a long-standing mystery. Marine science students at CR have deployed hundreds of drift bottles over the last 25 years. The bottles contain a card asking the finders to record the location in which they recovered the bottle, and send the card back to us.

In that time we have developed a fairly good idea of where California’s coastal currents are likely to carry our bottles. During our storm season, the nearshore Davidson Current tends to transport our bottles northward. We have very high recovery rates during those times in northern California, Oregon, and Washington. On occasion our bottles have made it as far as British Columbia and Alaska. The Davidson Current tends to be best developed between mid-October and mid-February, but southerly storm winds in late spring and early summer often produce the episodic, short-lived appearance of the Davidson Current.

The California Current, on the other hand, sweeps close to shore during much of the rest of the year. Our drift bottles are usually carried southward during these times. If you’ve been following this blog, you’ve undoubtedly noticed that our drifter has been swept over 200 nautical miles southward in the last month, successfully avoiding all of the most common stranding sites. During this time of year, most of our drift bottles are recovered along the Mendocino, Sonoma, and Marin County coastlines (counties that are north of the Golden Gate). Some of the bottles are carried south of the Golden Gate as far as Monterey County. The farthest south any of our bottles have ever been recovered is Big Sur.

Our drifter is now about 40 n.m. offshore along the Monterey coastline and rapidly approaching the latitude of Point Sur. For the last 25 years, the burning question has been, “Where do the bottles go if they don’t strand north of Big Sur?” Two of our bottles were recovered (several years apart) in the Philippines, but we have no other recoveries south or west of Pt. Sur. So, at long last, our drifter is on the verge of shedding some light on the mystery of where the surface currents carry our drift bottles.


The Great Escape

Finally! After a solid week of meandering around in the Gulf of the Farallons dodging tankers, warships, and fishing boats, CR’s drifter has been recaptured by the California Current and is heading south. The drifter has been sailing steadily southward for the last three days, and is now halfway between the Golden Gate and Monterey Bay.

The Monterey Bay, however, presents a new set of challenges. The currents there are notoriously variable as witnessed by Monterey Peninsula College’s two deployments of their drifter over the last seven months (See their posts  from November 17th of last year and February 3rd of this year). The excitement is building here again as the drifter approaches its next aquatic hurdle. Wake up Deidre, there’s some jetsam heading your way!


CR’s Drifter Playing a Dangerous Game

College of the Redwoods’ drifter has taken “playing on the freeway” to a new level. For the last four days, our drifter has been wandering around in the inbound and outbound shipping lanes (there are six of these) to the San Francisco Bay . Two hours ago it moved to within 10 nautical miles from the mouth of the San Francisco Bay and directly into the only major inbound shipping lane that goes under the Golden Gate Bridge!

The wind direction has  shifted back to the NW, so the drifter may be driven southward again. On the other hand, there is a spring flood tide cresting around 11:30 tonight that could drive the drifter closer to the bay. All of these options are only possible if (and this is a big IF) it manages to avoid the heavy ship traffic sailing into the bay. Watch with us on our Google Map page at,


Rural Drifter Heads for the Big City

No, this is not a Country & Western song. College of the Redwoods’ drifter finally escaped the clutches of the Bodega Triangle two days ago under the cover of darkness. In the same bold move, the drifter also slipped past the deadly clutches of Point Reyes. Safe? Not even! The drifter made an initial feint toward the Golden Gate, but then eased southward. Since then the drifter has been ambling through the major shipping lanes approaching the Golden Gate: dangerous waters! (

The NWS offshore forecast for the next four days calls for more unseasonal southerly winds (is this really MAY?), which could once again subject our valiant drifter to the possibility of being pushed back northward and onshore. Thus the potential for a visit to the Big City still remains a possibility.

Both of our local newspapers published articles on the drifter project (one on the front page), and tracking the drifter has become an obsession for many members of the general public as well as our students. Thanks to each and all of you (especially Jim Manning & Deidre Sullivan) that are responsible for making this project happen!


Trapped in the Bodega Triangle: Day 9

College of the Redwoods’ drifter continues to wander in a relatively small area that we have dubbed “The Bodega Triangle”.  After charging southward nearly 90 nm in the first 5 days after deployment, the drifter has since been cycling around an area of only a few square miles.  The seasonally unusual southerly winds over the last couple of days have been driving the drifter northward, but the forecast calls for a return of our typically strong northwesterlies today. I’m tempted to suggest that those winds may push the drifter southward again, but I have been surprised so many times over the last 9 days that I think I’ll just say, “Stay tuned for more excitement!”


CR drifter becalmed

For the first 5 days after deployment, strong NW winds fueled a current that carried College of the Redwoods’ drifter at speeds of well over 1 knot. Those winds died down on Sunday  and postponed our hopes of the drifter making it past Point Reyes. The past 36 hours have becalmed our drifter, and it has become a waiting game.

A weak front is predicted to slip through the area today, and with it will come southerly winds. Southerly winds could produce a northerly current, and more significantly, an onshore flow. The front is predicted to move through quickly, and our usually reliable NW winds should return tomorrow. Today produces another round of anxiety among the students and staff following the journey of the drifter. Will it be driven onshore today, or will tomorrow’s northwesterlies power our drifter past Point Reyers?

Regardless of the drifter’s immediate fate, the drifter has proven to be one of the most dynamic and powerful teaching tools I ever had. Each day’s odyssey has been a string of teaching and learning opportunities for all of us.


College of the Redwoods drifter continues

The excitement is building in our lab, as our drifter skirted by a major geographic hurdle. In our past studies Point Arena has captured many of our drift bottles. Early this morning the drifter we deployed two days ago (  ) successfully avoided the clutches of the Point and is continuing southward. The excitement is palpable in the lab and classroom. Students and staff are huddled around their computers for the position updates every 4 hours. Cheers actually broke out when the drifter missed Pt. Arena. Now we’re watching its course as it approaches the next big roadblock, Point Reyes.


College of the Redwoods deploys a new drifter

The students in our Marine Science Technology Program were excited to assemble our new drifter, but their enthusiasm was wavering as we waited weeks for good sea conditions. For those of you unfamiliar with the northern California coast, spring is a rather volatile time. Typically we have strong northwesterly winds at this time of year that fuel the upwelling that sustains an extremely productive marine ecosysytem. The California current (flowing from north to south) sweeps close to shore and gains momentum.  Winter storm winds, on the other hand, approach from the south and often produce a nearshore current (the Davidson Current) that flows from south to north and nudges the California Current offshore. Deploying the drifter involved waiting for the ideal window of opportunity: just after a front, with its southerly winds, sweeps by, and just before the northerly winds reappear to return the ocean surface to chaos.

This spring has been unusually violent and the seesaw of the California and Davidson Currents jockeying for nearshore dominance, and the nearly ceaseless winds, have kept the sea conditions very poor for a deployment.

This is the last week of our spring semester however, and I felt compelled to deploy the drifter before the students dispersed for the summer. We launched yesterday, and the sea conditions were perfect (if you like sea sickness). 10 to 12 foot, short period swells and rather chaotic seas did not, however dim the students’ enthusiasm. The winds (20 to 35 knots) were from the north and the surface flow was strongly southward. We were hopeful that the added influence of upwelling would force our drifter offshore and to the south.

For those of you that have already deployed a drifter, I’m sure you know what the next few hours were like waiting for a satellite fix. By the time our second fix arrived, it appeared our drifter was heading to shore. The students in our program have been conducting cheap, low-tech drift studies for almost 25 years now. We’ve been throwing drift bottles overboard with a printed message asking the finders to mail them back to us. It’s been tremendously successful, and we’ve received bottles from as far away as Alaska and the Philippines. In that time we’ve discovered that certain locations seem to catch more bottles than others.

Last night our drifter was heading for the dreaded Caspar Bay.Check out our Google Map page at: . By early this morning it was apparent that the drifter had skirted the foul place and was heading south. Past experience has indicated that we have two more major hurdles to bypass if our drifter is going to be in this for the long haul. The next is Pt. Arena, which the drifter should approach within the next day or two. We’re all holding our collective breath. If the drifter misses that roadblock, the next is Pt. Reyes.

In the past, if our drift bottles skirt Pt. Reyes they tend to travel to locations south of San Francisco or into the open Pacific. You’re all welcome to share our tension and excitement. Follow along on our Goggle Map site along with our students and the local community.

If you are an educator, I must say that this is the most excited I’ve seen my students about a single project in a long time. During yesterday’s deployment, the students were getting soaked by waves breaking over the boat’s bow, and everyone of them sported a grin that was, if possible, larger than their face.

Stay tuned for updates as our drifter approaches the much feared Point Arena.






Drifter Newsletter #5

Drifter Newsletter #6
February 2010

Drifter Website Update
We have made some progress in designing a new website to plot all the drifter tracks and to serve the data but we have not yet released it. It will take the place of the rather cluttered site: before the 2010 drifter season gets underway in a few months. Tanya Stoyanova, a computer science student from Bulgaria, is working on it one day per week.

Figure 1. Example of comparing an observed drifter track (blue) with simulated forecast tracks (other colors). In this case, we are using the UMASS-Dartmouth’s FVCOM model output on the “GOM2 grid” provided on the web. We are developing a routine to track particles through their 3-d velocity fields.

Figure 1. Example of comparing an observed drifter track (blue) with simulated forecast tracks (other colors). In this case, we are using the UMASS-Dartmouth’s FVCOM model output on the “GOM2 grid” provided on the web. We are developing a routine to track particles through their 3-d velocity fields.

Collaboration with Coast Guard
Working with SMCC and UMASS-D, we provided the USCG with one of our drifters which they deployed off of Cape Elizabeth Maine in mid-January 2010 (see Fig 1). This was part of the USCG Search and Rescue Training Operations where they practice some of their routines following drifting objects over the coarse of several days. Since we have similar interests for scientific reason (such as following patches of toxic algae), we are trying to combine our efforts in this endeavor. Animation of these forecasts vs observed tracks are linked from the drifter website but may be found directly is at, for example: If you are interested in implementing this sort of forecast operation in your waters, let us know. All you need is to find a URL for some webserved “CF-compliant” circulation output in your local waters and a MATLAB programmer.

COSEE podcast
Ari Daniel Shapiro’s interview with us including a trip to Casco Bay to deploy drifters was released last week and posted on the COSEE NOW website where it will be heard by many educators and their students around the country. It can be found at

New Drifter Deployers
We are happy to add Long Beach Community College from California, Clatsop Community College from Washington State, and the Atlantic Salmon Federation from New Brunswick, Canada to the list of drifter users. LBCC students are actively designing new rigs to radio track bucket drifters in Los Angeles river runoff events. CCC students are following their surface drifters (rachels) rapidly moving north and east of their deployment location off Astoria. ASF will be deploying several drifters in the St Lawrence River in May to track the potential transport of young smolts.

New Transmitters on the Market
We are watching the development of various transmitters such as the new “Spot2” come on the market. There are a variety of options available “off-the-shelf” for doing our sort of tracking but we are sticking to the TrackPack II in 2010. Given its increased battery power this year and improve circuitry, we are hoping it will serve our needs. We will see.

Figure 2. Approximate location, institution, #, purpose, principal investigator, and month of SMCC/eMOLT drifter deployments planned for 2010 on the northeast continental shelf.

Figure 2. Approximate location, institution, #, purpose, principal investigator, and month of SMCC/eMOLT drifter deployments planned for 2010 on the northeast continental shelf.

Drifter plans for 2010
More than 100 drifter deployments will be made this year (Fig 2) to document flow patterns around the Gulf of Maine. Most of the deployments this year will be made in Massachusetts Bay. The state has funded a project, for example, to investigate the potential effects of the LNG facility on the lobster population. We will deploy dozens of drifters in the coastal waters north and south of Boston Harbor. Some of the drifters for this project will be put together by the Center for Student Coastal Research in Cohassett, MA. In exchange for their efforts, they will get several drifters of their own to deploy in their local harbor to examine the exchange mechanisms with the bay.


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