Rogue waves

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Context:  Scientists found a way to predict Rogue Waves using Artificial Intelligence

Details

Rogue Waves

• Rogues, called 'extreme storm waves', are those waves which defy the average sea state and greater than twice the size of surrounding waves.
• Also known as freak, or killer waves.

Sea State

In oceanography, sea state refers to the condition of the surface of a large body of water at a certain location, at a certain point of time.

The World Meteorological Organization (WMO) sea state code characterises sea state based on wave height on a scale of 0 (no waves) to 9 (waves over 14 m).

Characteristics

• Unpredictable, and often come from directions other than prevailing wind and waves.
• Most reports of extreme storm waves say they look like "walls of water."
• They are often steep-sided with unusually deep troughs.

Formation

Constructive interference.

• Extreme waves often form because swells, while traveling across the ocean, do so at different speeds and directions.
• As these swells pass through one another, their crests, troughs, and lengths sometimes coincide and reinforce each other.
• This process can form unusually large, towering waves that quickly disappear.
• If the swells are travelling in the same direction, these mountainous waves may last for several minutes before subsiding.

Focusing of wave energy.

• When waves formed by a storm develop in a water current against the normal wave direction, an interaction can take place which results in a shortening of the wave frequency.
• This can cause the waves to dynamically join together, forming very big 'rogue' waves.
• Extreme waves developed in this fashion tend to be longer lived.

Other Ocean Waves and Characteristics

Type	Description
Wind Waves	Generated by local wind conditions and are the most common type of ocean waves.
Swell Waves	Long-period waves that have traveled over long distances and are often generated by storms in remote areas.
Seiche Waves	These are standing waves that occur in enclosed or partially enclosed bodies of water due to factors like atmospheric pressure changes and seismic activity.
Tsunami Waves	Seismic sea waves caused by underwater earthquakes, volcanic eruptions, or landslides. Tsunamis can travel across entire ocean basins and have destructive power when they reach shore.

Characteristics Crest: The highest point of a wave. Trough: The lowest point of a wave. Height: It is the distance between a wave crest and wave trough. Amplitude: The distance between the crest or the trough to the still water line in between them is the amplitude. It is the size of a given wave. Wavelength: The distance that one wave travels before it repeats itself is it’s wavelength. It is the distance between the centers of two consecutive rarefactions or compressions. Time Period: It is the time required for two successive crests to pass a fixed point or the time required to produce a single complete wave, or cycle. Frequency: The number of waves that cross a fixed point in a given amount of time is the frequency. Velocity: The amount of distance in meters per second that a wave travels in one second is it’s velocity.

Instances

History of rogue wave knowledge

• In 1826, French scientist Captain Jules Dumont d'Urville reported waves as high as 33 m (108 ft) in the Indian Ocean.
• The Draupner wave (or New Year's wave) was the first rogue wave to be detected in 1995 by a measuring instrument in North Sea.

Recent Instances

• The currents where these are sometimes seen are the Gulf Stream and Agulhas current.
• On 17 November 2020, a buoy moored in 45 metres (148 ft) of water on Amphitrite Bank in the Pacific Ocean.

Predictions and Consequences

• Since these waves are uncommon, measurements and analysis of this phenomenon is extremely rare. Exactly how and when rogue waves form is still under investigation.
• The lack of a real-time forecasting method has had deadly consequences: between 2011 and 2018, rogue waves killed at least 386 people and sank 24 ships

Recent Development

AI Training and Prediction

• A research conducted by Breunung and Balachandran (Mathematicians) considered 20-minute long samples recorded by ocean buoys.
• For samples containing rogue waves, the recording ends at the point when the rogue waves occur.
• The rogue wave samples were then compared to all other samples (in which rogue waves did not occur) to train the AI programme.

Key Findings

• Programme was subsequently able to predict about 75% rogue waves one minute in advance. Roughly 73% rogue waves could be predicted five minutes in advance.

Suggestions

• The accuracy and advance warning time of the AI’s forecasts could be further improved by incorporating physical quantities such as water depths, wind speeds, and buoy locations.
• Harnessing more powerful AI architectures alongside more data may even lead to near-perfect predictions in the future.

Sources:

Indian Express.

PRACTICE QUESTION Q. Integrating frontier technologies including Artificial Intelligence (AI) into existing emergency systems can harness the potential of existing data streams and improve hazard mitigation and disaster management. Discuss 150 words