PAPA MAU: Liquid Robotics' wave-powered sub Papa Mau autonomously traveled 16,668 kilometers across the Pacific Ocean, in the process studying rogue waves and other oceanic phenomena undetected by satellites in the worldwide communications system.
Image: Courtesy of Liquid Robotics
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When the robotic Papa Mau completed its 16,668-kilometer scientific expedition across the Pacific Ocean last month, the surfboard-sized submarine did more than set a new world record for the longest distance traveled by an autonomous vehicle. The wave-powered sub reached Australia’s Hervey Bay with a load of data that will keep marine biologists, oceanographers and other scientists busy for quite some time, including observations of rogue waves that satellites failed to detect during the Papa Mau’s year-long voyage.
On what appeared to be a calm, sunny day last February, Papa Mau transmitted data indicating rough weather—six- to 7.6-meter rolling seas and winds blowing at 50 knots. The sub had been at sea since November 17, 2011, the first of a fleet of four robot subs (called Wave Gliders) launched from San Francisco Bay by Liquid Robotics, Inc.
“There was not a cloud in the sky, nothing was on the satellites,” says Bill Vass, CEO of Sunnyvale, Calif.-based Liquid Robotics, a provider of ocean data services for shipping, energy and environmental companies. “And we said, ‘Oh, there must be something wrong with [the submarine’s] sensors.’ But when all four robots saw [the waves], we turned on the cameras. It was pretty astounding.” Nearby, an unfortunate sailboat lost its mast and was rescued by a Dutch freighter. “Besides that sailboat, the freighter, and us, no one would have seen those waves,” Vass adds.
Maritime history is filled with fantastical stories of rogue waves that appear suddenly, like walls of water, to swamp unsuspecting sailors and their vessels. As recently as 2010, several such monstrous waves hit the cruise ship Louis Majesty in the Mediterranean off the coast of Spain, an incident that killed two people and injured six.
Satellites in the worldwide communications system used for transmitting data from offshore locations “make their best guess” from 400 kilometers up about weather conditions at sea, including wind speeds and wave heights, according to Vass. They not only miss giant waves but are “tremendously inaccurate” in estimating the speeds of current and wave direction, he says
After comparing satellite data with his robots’ findings, Vass believes satellites detect surface shear, which comes from winds and broad currents. There are two dimensions to surface shear. One is the difference in currents at the ocean’s surface compared with those flowing at lower levels of the water column. The second occurs when two currents collide and generate smaller localized eddies and turbulence. Both are important to know when determining circulation and its effect on shipping energy usage and fuel consumption.
“We’re finding the satellites are way off for microcurrents,” Vass says. “In many cases, the satellite models were showing currents 180 degrees off from the currents we actually experienced, and off by a factor of two to three in speed. Our robots feel the first eight meters of ocean.” A drifter—a buoy that may submerge to a depth, then rise to the surface while tracking the path of a current—might detect a surface current, and a satellite might “see” the first few inches of the ocean, but Vass says his robot gliders “feel the full breadth of the current.” As such, the gliders ran through a series of eddies that were invisible to the satellites. They also crossed the equator where, according to satellite models, a huge shear current was thought to run east to west. Yet the flotilla experienced none of that. Upwellings, rising masses of water that can be small or enormous and that often carry deep ocean nutrients to the surface, were also in the wrong places compared to what the satellites indicated, he adds.
“The speed and directions of currents have major effects on the shipping industry, oil and gas and marine operations, as well as global weather,” Vass says. “The robot gliders’ ability to show measurements will change the way many of these industries work in the future.”
Others are more skeptical of the significance of the gliders’ findings and point out that the limitations of satellite observations are already well known. Oscar Schofield, a Rutgers University professor of bio-optical oceanography thinks that Liquid Robotics is overstating the importance of its findings. “I wouldn’t take such a negative tone,” he says. “We’ve been well aware for a long time––since we put the satellites up––that they are limited. They are the only way to provide a global view of the ocean, albeit weighted to the surface, but they are still the most effective tool.”
The question is how to fill in the subsurface, 3-D structure, Schofield says. Robotic gliders—including those made by Liquid Robotics and Falmouth, Mass.-based Teledyne Webb Research—as well as scientific buoys like the Argos drifter are filling the data gap, he adds.
In June, Liquid Robotics’ gliders also documented a more than 1,900-kilometer-long chlorophyll and plankton bloom—the largest ever and not usually seen that time of year—initially undetected by satellites. “At this resolution, the chlorophyll bloom provides a groundbreaking link between scientific modeling and in-situ measurement and real-time data transmission,” says Liquid Robotics oceanographer Luke Beatman. The finding is significant because algae and phytoplankton are the base of the oceanic food chain and also regulate climate by absorbing carbon dioxide from the atmosphere.
Commenting on algal bloom, Scott Glenn, a Rutgers University professor who specializes in physical oceanography, says he finds that “the near-surface spatial maps of temperature and phytoplankton distributions obtained by satellite combined with the vertical profiles obtained from underwater profiling robots and gliders are very powerful observational tools, illuminating a chronically undersampled ocean that varies rapidly in space and time.”
Satellites provide maps of instants in time whereas surface wave gliders and underwater profiling gliders provide time series that move around underneath these maps, and can be redirected by these maps to the areas of greatest interest, Glenn says, adding that he prefers to use all three means simultaneously for “sustained sampling trajectories through this unseen world.” Both Glenn and Schofield are part of Rutgers’ Institute of Marine and Coastal Sciences Coastal Ocean Observation Lab.
Papa Mau’s journey came to a close when it arrived in Bundaberg, Australia, on November 20, having weathered gale-force storms, fended off sharks, skirted around the Great Barrier Reef, and finally battled and surfed the East Australian Current to reach its destination Down Under. The robot gliders could change the economics of sea exploration and monitoring. The average research vessel costs $37,500 per day due to fuel, crew and maintenance, so an expedition like Papa Mau’s by ship could cost tens of millions of dollars. Instead, each robot glider costs up to $3,000 per day.
Next up, Liquid Robotics has chosen five teams of scientists to study the new data. Researchers from University of California Merced, University of California Santa Cruz, Scripps Institution of Oceanography, University of Texas and Boston-based software firm Wise Eddy will use the information to analyze the ocean’s health and respiration, its biomass and other information about organisms critical to ocean life.
The second robot glider, Benjamin, is expected to arrive in Australia in early 2013. The two others are being repaired in Hawaii and will eventually swim to Japan. Liquid Robotics is next contemplating a robot sub mission circumnavigating Antarctica.
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14 Comments
Add Comment"On what appeared to be a calm, sunny day last February, Papa Mau transmitted data indicating rough weather—six- to 7.6-meter rolling seas and winds blowing at 50 knots."
Reply | Report Abuse | Link to thisThe above description of what is described as 'rogue waves' is not consistent with the established use of that term.
http://en.wikipedia.org/wiki/Rogue_wave
"In oceanography, they are more precisely defined as waves whose height is more than twice the significant wave height (SWH), which is itself defined as the mean of the largest third of waves in a wave record."
Rogue waves are thought to occur as a single anomalously large wave produced by the interactions of many much smaller waves, although their exact cause has not been determined. As I understand, these single events can often occur during storms, but they can also occur during calmer conditions.
The Wikipedia entry's "History" section begins:
"It is common for mid-ocean storm waves to reach 7 metres (23 ft) in height, and in extreme conditions such waves can reach heights of 15 metres (49 ft)."
It goes on to state that "Research has confirmed that waves of up to 35 metres (115 ft) in height are much more common than mathematical probability theory would predict using a Rayleigh distribution of wave heights."
The wave conditions detected by the robotic glider do not seem to qualify as 'Rogue Waves.'
It seems that there are some major holes in the climate
Reply | Report Abuse | Link to thismodels. I wonder how long it will take the warmests to fit this new data to their vision.
Aww come on dbtinc fess up. We know you are furiously
Reply | Report Abuse | Link to thisscribbling as I write this.
This data may indeed support the man made global warming theory. All I want you guys to do is wait a couple yrs until some real research can be conducted vetted and published before you say this might support the global warming theory which might be causing more hurricanes , which might be causing more drought, which might be causing polar ice cap melting. Which might be causing ( insert your desired weather Phenomenon here ).
:)
@ jtdwyer - the rouge wave reported was not at the same time as the other storm - go back and reread the article.
Reply | Report Abuse | Link to thisI don't think so - read it again!
Reply | Report Abuse | Link to thisThe rogue wave idea was introduced in paragraph 1. P2 described the storm event, P3 further discussed reaction to it, P4 discussed rogue waves in general.
If P2 & P3 were not discussing the alleged rogue wave event (even though they did not mention it by name), there is no discussion of any rogue wave event included anywhere in the article.
I am curious if anyone has tried using a similar type of electronic surfboard to catch fish.
Reply | Report Abuse | Link to thisInteresting thought, but wouldn't other fish eat the catch?
Reply | Report Abuse | Link to thisjtdwyer,
Reply | Report Abuse | Link to thisMy interpretation of the wiki entry on rogue waves is different than yours. Your first quotation of wiki should have contained the next sentence:
"Therefore rogue waves are not necessarily the biggest waves found at sea; they are, rather, surprisingly large waves for a given sea state."
Therefore, if the surface of a body (or point or area?) of water is calm and the SWH (significant wave height) is one foot, then a rogue wave would be defined as anything over 2 ft.
As was said in the article: "There was not a cloud in the sky, nothing was on the satellites."
In the photo of Papa Mau provided in the article, for example, what would your best guess of the SWH be?
Cramer, JT is right, deal with it.
Reply | Report Abuse | Link to thisJerryDwyer,
Reply | Report Abuse | Link to thisScientists studying rogue waves do not seem to agree with you.
See:
Rogue Wave Observation in a Water Wave Tank
A. Chabchoub, N. P. Hoffmann, and N. Akhmediev
Physical Review Letters 106, 204502 (2011)
http://prl.aps.org/abstract/PRL/v106/i20/e204502
referenced in:
Ship in Bottle, Meet Rogue Wave in Tub
by Adrian Cho on 3 May 2011
http://news.sciencemag.org/sciencenow/2011/05/ship-in-bottle-meet-rogue-wave.html?ref=hp
I'm not sure what your point is, but thanks for making mine for me. My point was that a rogue wave is a singular wave of exceptional height, not a series of large waves, described in this article as "six- to 7.6-meter rolling seas and winds blowing at 50 knots."
Reply | Report Abuse | Link to thisYour first reference's abstract (can't freely access the report), "Rogue Wave Observation in a Water Wave Tank" concludes with the statement:
"... we present the first experimental results with observations of the Peregrine soliton in a water wave tank."
http://en.wikipedia.org/wiki/Soliton
"In mathematics and physics, a soliton is a self-reinforcing solitary wave (a wave packet or pulse) that maintains its shape while it travels at constant speed."
Your second reference also discusses Peregrine solitons.
jtdwyer,
Reply | Report Abuse | Link to thisIt looks like we agree on the definition of a rogue wave.
It looks like vague statements that were misunderstood resulted in our perceived disagreement.
I agree that the sentence you quoted from Karen Frenkel was very poorly written and misleading. First, "rolling seas" sounds like a discription of an ongoing "sea state." Second, did the Papa Mau actually measure "winds blowing at 50 knots" or was it a gust or was it her embellishment in describing "rough weather?"
It would help to have a better description of the actual data recorded by the Wave Gliders and the eye witness account from the sailors rescued by the Dutch freighter.
However, it also appeared to me that you were claiming that "it is common for mid-ocean storm waves to reach 7 metres (23 ft) in height;" and therefore waves of 7 meters in height are not rogue. I guess I misunderstood your point.
I see. My intention with that particular statement from the Wikipedia Rogue wave entry was to establish that the only waves reported in this article could easily be common mid-ocean storm waves. I'm glad that's resolved - thanks!
Reply | Report Abuse | Link to this"each robot glider costs up to $3,000 per day" - that seems fairly high. I wonder how much is overhead, and what the marginal costs of each glider is. One would think that a larger fleet of these would result in much lower costs to operate each.
Reply | Report Abuse | Link to this