Archive for the ‘Ocean Models’ Category

Search status

Friday, February 16th, 2007

Since January 28, the San Francisco police, the Coast Guard and Jim’s friends and family have conducted an extensive search to find him and his sailboat, Tenacious, off the California coast. I want to summarize the status of that search here, so that the broad volunteer community that’s done so much knows where we stand.

The Coast Guard’s air and surface search covered 132,000 square miles in the days immediately following Jim’s disappearance. This search was thorough: Planes, boats and helicopters covered much of the region repeatedly. Radio broadcast alerts were made for a week, and all marinas and harbors were canvassed repeatedly. It found no trace of Tenacious or Jim.

During the Coast Guard search and in the days that followed it, Jim’s friends and family assembled satellite imagery, collected wind and current data and arranged for more air and surface searches over the ocean and coast from Oregon and into Mexico. We have walked stretches of coastline and have postered marinas with details on the missing boat. The story has drawn attention from around the world.

Based on our knowledge of the boat and weather conditions, we do not believe that Tenacious could have outsailed our search, whether it was under power, adrift, sailing under autopilot, or even sailing at best possible speed. We have covered an enormous area.

In the last several days, the Friends of Jim group has reviewed all the data with Coast Guard officials. The fact is that we have no evidence as to what has happened to Tenacious or to Jim Gray. Neither we nor the Coast Guard can come up with a surface search plan that is likely to find either Tenacious or Jim, given everything that has been done already.

Accordingly, the Friends of Jim group is suspending its active effort to find Tenacious that has been centered here at the blog. For both the Coast Guard and the Friends of Jim, “suspension” means that the active search has been discontinued due to exhausting all present leads and the lack of new information. Of course, should we or the Coast Guard receive any new information, we will investigate it.

Understandably, Jim’s family is determined to continue to seek answers, but they deserve to be able to pursue them privately. The family deeply appreciates everything the Coast Guard and Friends of Jim have done.

Jim’s wife Donna asked me to add this statement of thanks from her on behalf of the family:

On behalf of our entire family, I would like to thank every individual and organization who helped, and is continuing to help, in a long and difficult search. As the search takes on a new direction, I want you to know that your faith, hard work and boundless creativity sustain us during this unbearable time.

Jim is very lucky to have you as friends and colleagues, and we are very lucky and grateful to have your support.

Below, in the previous post to the blog, we have posted recent photos of Jim, photos of Tenacious at anchor and under sail, and an email address where you can send any information that could help us with our search. Coast Guard and San Francisco Police contact numbers are also listed.

  • The e-mail address is search.jimgray@gmail.com.
  • The Coast Guard contact number is (415) 399-3547.
  • The San Francisco police department contact number is (415) 553-1071.

Thank you, one and all, for this amazing effort to find our Jim.

Contact information and photos

Friday, February 16th, 2007

Anyone with information about Tenacious or Jim Gray should contact:

  • The San Francisco Police Department at (415) 553-1071.
  • The US Coast Guard at (415) 399-3547.
  • Our search email address, search.jimgray@gmail.com.

Jim was last seen on January 28, 2007. Here are several photographs of him and of his 40-foot C&C sailboat, Tenacious, sail number 31869.

Jim Gray

Jim Gray

Tenacious

Tenacious

Animation of Ocean Models

Wednesday, February 14th, 2007

Animation of Ocean Models

Using ocean current models provided by the OurOcean group at JPL, we created an animated GIF, which shows where objects starting near the Farallons on the afternoon Jim disappeared would drift over the next 13 days. Relevant satellite and aerial imagery were obtained 2.6, 4.8, 5.1, and 5.8 days after the adopted zero point in time (Jan 29, 00:00 GMT). We are now reanalyzing the imagery that covers the convergence zones in the current models.

http://skydev.pha.jhu.edu/nieto/Tenacious/

The JHU group

Note: In addition to the movie, we have added the data as suggested by Igor Carron

Status update: Connecting Remote Sensing to Trajectory Generation

Sunday, February 4th, 2007

A report from Microsoft’s Jim Karkanias

Just-concluded phone call regarding coordination of remote sensing and trajectory generation.

Participants:

JPL: Yi Chao; Monterey Bay Aquarium Research Institute: Jim Bellingham; Center for Coastal Margin and Observation: Antonio Baptista; Oracle: Mike Olson; IEEE/Intel: David Tennenhouse; MSFT: Dave Campbell, Phil Garrett, Jim Karkanias

Items:

MSFT:  A log of cell phone connectivity indicates that Jim Gray’s phone was communicating approx every 15 min with Exchange from 5:08am pst to 11:50am pst. Voice calls from his phone at ca. 10:38 put him at mile 15/16 (based on his relayed report) at which point he began to lose cell connectivity for voice calls (based on his relayed report). His phone continued to sync until 11:50am putting him at an estimated 22 miles from GG - consistent with expected loss of cell signal at approx this point. An increase in both frequency and latency of retry attempts suggests (this is theory) degradation of cell signal supporting this westward trajectory. There are no cell towers on the Farallon Islands. An eye witness on Farallon Islands saw a sail boat at a time/place that matches this theory - his description matches the boat but he has yet to id by photo. An important outstanding question is whether the sails were up or not.

JPL:  Currently calculating trajectory data based on 5days of telemetry data from a buoy released by the CG during a search run. This data will be very useful in calculating a forward map of Jim’s boat if it is without a helmsman. This will soon be made available as a web service tool that can accept lat/long, etc. to forward calc a result

CMOP: Using particles based analysis applied to water parcels, the team will attempt to backward map a large space of possible endpoints to calculate the probabilities of paths that in the past would have intersected our proposed starting area (in the vicinity of Farallon somewhere between after where his cell lost signal, ie 22 miles out).

MBARI: Coordinating contacts across this project and will be setting up a collab website for this by 7pm pst

Oracle: Mike Olson and David Tennenhouse will be intersecting all of the above to create a bounding box for the MTurk and related image processing data. Georeferencing the images based on what the forward/backward maps suggest as probable paths should constrain the image processing task and help inform search.

Surface currents

Friday, February 2nd, 2007

Below find some discussion of offshore currents and winds, ocean models, and links to data/animations.  A previous post (http://openphi.net/tenacious/?p=7) provided links to HF radar measurements of currents in the general region in which Jim was sailing and some specific information.   However, the present search area is much larger and far beyond the range of HF radar. 

 First, Francisco Chavez, provided the following comments:

“Here are some thoughts regarding the general circulation during this time of the year.

The winter is commonly dominated by the appearance/intensification of the Davidson current which flows poleward along the coast. In an average year a particle, drifter or sailboat would be advected northward and eventually onto shore. Flow north of the olden Gate is often northward.

Having said that this has been an unusual year in terms of wind patterns with stronger than average  nothwesterly wind, upwelling and perhaps California Current. The combined effect of the ocean and wind on a sailboat would act to move it offshore almost perpendicular to the coast (with a bit of a southward component) until it reached between 100 and 200 km when flow would become southerly.

So two very different options but it does cut down a few search quadrants.If he went north he is likely to be close to the shore or on the beach, if he went south then offshore and close to the time when it might turn southerly.Hope this helps”

Now, moving to some model output.  Winds are not a bad proxy for surface currents.  There is a wind product produced by the Naval Research Laboratory and served by JPL below:

http://ourocean.jpl.nasa.gov/cgi-bin/dataset_new.cgi?category_id=3&description=Center%20for%20Integrated%20Marine%20Technologies%20(CIMT)&template=cimt.html

Ocean models are not as far advanced with respect to capabilities as are atmospheric models (it is a harder problem).  The ocean is much more variable than the atmosphere, and harder to observe.  In the offshore region, where there are effectively very few measurements of ocean conditions, the situation is too challenging to expect ocean models to provide reliable output with respect to details of circulation.  However, having said that, there are surface current available from various ocean models.  One such model is operated at JPL.

http://ourocean.jpl.nasa.gov

An animation of the output of the JPL model run has been put together by Mike Godin, and can be obtained at: 

http://aosn.mbari.org/tenacious/

Finally, the HF radar links (described in more detail in the post identified at the start of this note) are::

http://cencalcurrents.org/   Surface current for SF.

http://www.cencalcurrents.org/Plots/SFB1/trj/2007_01/animation_2007_01_29_1000.gif    Animation for surface currents showing trajectories of water parcels on July 28 (the day Jim disappeared)

http://www.cencalcurrents.org/Plots/SFB1/trj/2007_01/   Animation files.

Our experience with the HF radar in Monterey Bay is that the HF radar trajectories do a reasonable job of matching the paths of surface drifters.

-Jim Bellingham