{"id":7869,"date":"2016-02-26T09:55:42","date_gmt":"2016-02-26T09:55:42","guid":{"rendered":"http:\/\/revoscience.com\/en\/?p=7869"},"modified":"2016-02-26T09:55:42","modified_gmt":"2016-02-26T09:55:42","slug":"rogue-wave-ahead","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/rogue-wave-ahead\/","title":{"rendered":"Rogue wave ahead"},"content":{"rendered":"

New prediction tool gives 2-3 minute warning of incoming rogue waves.<\/strong><\/em><\/span><\/p>\n

\"\u201cThese<\/a>
\u201cThese waves really talk to each other,\u201d Themis Sapsis says. \u201cThey interact and exchange energy. It\u2019s not just bad luck. It\u2019s the dynamics that create this phenomenon.\u201d
Image: MIT News<\/figcaption><\/figure>\n

CAMBRIDGE, Mass<\/strong>. —\u00a0Sailing history is rife with tales of monster-sized rogue waves \u2014 huge, towering walls of water that seemingly rise up from nothing to dwarf, then deluge, vessel and crew. Rogue waves can measure eight times higher than the surrounding seas and can strike in otherwise calm waters, with virtually no warning.<\/span><\/p>\n

Now a prediction tool developed by MIT engineers may give sailors a 2-3 minute warning of an incoming rogue wave, providing them with enough time to shut down essential operations on a ship or offshore platform.<\/span><\/p>\n

[pullquote]The combination of statistics and dynamics helped the team identify the length-scale of a critical wave group, which has the highest likelihood of evolving into a rogue wave.[\/pullquote]<\/p>\n

The tool, in the form of an algorithm, sifts through data from surrounding waves to spot clusters of waves that may develop into a rogue wave. Depending on a wave group\u2019s length and height, the algorithm computes a probability that the group will turn into a rogue wave within the next few minutes.<\/span><\/p>\n

\u201cIt\u2019s precise in the sense that it\u2019s telling us very accurately the location and the time that this rare event will happen,\u201d says Themis Sapsis, the American Bureau of Shipping Career Development Assistant Professor of Mechanical Engineering at MIT. \u201cWe have a range of possibilities, and we can say that this will be a dangerous wave, and you\u2019d better do something. That\u2019s really all you need.\u201d<\/span><\/p>\n

Sapsis and former postdoc Will Cousins have published their results this week in the\u00a0Journal of Fluid Mechanics.<\/em><\/span><\/p>\n

\u201cNot just bad luck\u201d<\/strong><\/span><\/p>\n

Like many complex systems, the open ocean can be represented as a chaotic mix of constantly changing data points. To understand and predict rare events such as rogue waves, scientists have typically taken a leave-no-wave-behind approach, in which they try to simulate every individual wave in a given body of water, to give a high-resolution picture of the sea state, as well as any suspicious, rogue-like activity. This extremely detailed approach is also computationally expensive, as it requires a cluster of computers to solve equations for each and every wave, and their interactions with surrounding waves.<\/span><\/p>\n

\u201cIt\u2019s accurate, but it\u2019s extremely slow \u2014 you cannot run these computations on your laptop,\u201d Sapsis says. \u201cThere\u2019s no way to predict rogue waves practically. That\u2019s the gap we\u2019re trying to address.\u201d<\/span><\/p>\n

Sapsis and Cousins devised a much simpler, faster way to predict rogue waves, given data on the surrounding wave field.<\/span><\/p>\n

In previous work, the team identified one mechanism by which rogue waves form in unidirectional wave fields. They observed that, while the open ocean consists of many waves, most of which move independently of each other, some waves cluster together in a single wave group, rolling through the ocean together. Certain wave groups, they found, end up \u201cfocusing\u201d or exchanging energy in a way that eventually leads to an extreme rogue wave.<\/span><\/p>\n

\u201cThese waves really talk to each other,\u201d Sapsis says. \u201cThey interact and exchange energy. It\u2019s not just bad luck. It\u2019s the dynamics that create this phenomenon.\u201d<\/span><\/p>\n

Going rogue<\/strong><\/span><\/p>\n

In their current work, the researchers sought to identify precursors, or patterns in those wave groups that ultimately end up as rogue waves. To do this, they combined ocean wave data available from measurements taken by ocean buoys, with nonlinear analysis of the underlying water wave equations.<\/span><\/p>\n

Sapsis and Cousins used the statistical data to quantify the range of wave possibilities, for a given body of water. They then developed a novel approach to analyze the nonlinear dynamics of the system and predict which wave groups will evolve into extreme rogue waves.<\/span><\/p>\n

They were able to predict which groups turned rogue, based on two parameters: a wave group\u2019s length and height. The combination of statistics and dynamics helped the team identify the length-scale of a critical wave group, which has the highest likelihood of evolving into a rogue wave. Using this, the team derived a simple algorithm to predict a rogue wave based on incoming data. By tracking the energy of the surrounding wave field over this length-scale, they could immediately calculate the probability of a rogue wave developing.<\/span><\/p>\n

\u201cUsing data and equations, we\u2019ve determined for any given sea state the wave groups that can evolve into rogue waves,\u201d Sapsis says. \u201cOf those, we only observe the ones with the highest probability of turning into a rare event. That\u2019s extremely efficient to do.\u201d<\/span><\/p>\n

Sapsis says the team\u2019s algorithm is able to predict rogue waves several minutes before they fully develop. To put the algorithm into practice, he says ships and offshore platforms will have to utilize high-resolution scanning technologies such as LIDAR and radar to measure the surrounding waves.<\/span><\/p>\n

\u201cIf we know the wave field, we can identify immediately what would be the critical length scale that one has to observe, and then identify spatial regions with high probability for a rare event,\u201d Sapsis says. \u201cIf you are performing operations on an aircraft carrier or offshore platform, this is extremely important.\u201d<\/span><\/p>\n

This research was supported in part by the Office of Naval Research, the Army Research Office, and the American Bureau of Shipping.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Now a prediction tool developed by MIT engineers may give sailors a 2-3 minute warning of an incoming rogue wave, providing them with enough time to shut down essential operations on a ship or offshore platform.<\/p>\n","protected":false},"author":6,"featured_media":7870,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14,17],"tags":[],"class_list":["post-7869","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-innovation","category-research"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0-150x150.jpg",150,150,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0-300x200.jpg",300,200,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",95,63,false],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",448,299,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",96,64,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2016\/02\/MIT-Rogue-Waves_0.jpg",150,100,false]},"author_info":{"info":["Amrita Tuladhar"]},"category_info":"Innovation<\/a> Research<\/a>","tag_info":"Research","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/7869","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=7869"}],"version-history":[{"count":0,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/7869\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/7870"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=7869"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=7869"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=7869"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}