Perfect storm: What is the Fujiwhara Effect?
- January 4, 2023
- Posted by: OptimizeIAS Team
- Category: DPN Topics
Perfect storm: What is the Fujiwhara Effect?
- Super cyclone Hinnamnor and tropical storm Gardo approach each other and Hinnamnor devours the Gardo, making final landfall in the South Korea region, a phenomenon known as the Fujiwhara effect.
Merger of two storms-
- When two ocean storms form in the same region, their wind circulations start meeting each other at the mid and higher levels.
- This meeting of winds makes a bond between the two storms like a connecting limb through which they start influencing each other.
- In this case, Hinnamnor’s intensity decreased and Gardo vanished.
- But in an increasingly warming world, a merger between two large enough tropical cyclones over any of the global oceans could lead to the formation of a mega cyclone, causing devastation along coastlines.
Recent incidents of storm merger-
- In recent years, several storms have come close to undergoing the Fujiwhara effect.
- Just a week after Hinnamnor engulfed Gardo, two hurricanes—Danielle and Earl—formed one after the other in the North Atlantic Ocean, sparking fears of the Fujiwhara effect.
- Around the same time, another hurricane— Kay—also brewed in the eastern Pacific Ocean.
- In 2020 hurricanes Marco and Laura had formed back to back in the small region of the Gulf of Mexico and created a possibility of the Fujiwhara effect.
THE FUJIWHARA effect-
- THE FUJIWHARA effect is any interaction between tropical storms formed around the same time in the same ocean region with their centres or eyes at a distance of less than 1,400 km, with intensity that could vary between a depression (wind speed under 63 km per hour) and a super typhoon (wind speed over 209 km per hour).
- The interaction could lead to changes in the track and intensity of either or both storm systems.
- In rare cases, the two systems could merge, especially when they are of similar size and intensity, to form a bigger storm.
- There are five different ways in which the Fujiwhara effect can take place.
- The first is elastic interaction in which only the direction of motion of the storms changes and is the most common case.
- These are also the cases that are difficult to assess and need closer examination.
- The second is partial straining out in which a part of the smaller storm is lost to the atmosphere.
- The third is complete straining out in which the smaller storm is completely lost to the atmosphere.
- The straining out does not happen for storms of equal strength.
- The fourth type is a partial merger in which the smaller storm merges into the bigger one.
- The fifth is a complete merger which takes place between two storms of similar strength.
- During a merger interaction between two tropical cyclones, the wind circulations come together and form a sort of whirlpool of winds in the atmosphere.
- The Fujiwhara effect was identified by Sakuhei Fujiwhara, a Japanese meteorologist whose first paper recognising the Fujiwhara cases was published in 1921.
- The first known instance of the effect was in 1964 in the western Pacific Ocean when typhoons Marie and Kathy merged.
Is the frequency of the Fujiwhara effect increasing?
- Research shows that it is. Just between 2013 and 2017, there were 10 cases of the Fujiwhara effect, mostly weak interactions, in the northwest Pacific Ocean.
- As the oceans get warmer and there is more number of stronger cyclones the possibility of the Fujiwhara effect would increase drastically as it already has.
- There has been a 35 per cent increase in the strength of typhoons that have hit Taiwan between 1977 and 2016.
- This happened due to a 0.4 to 0.7°C rise in the sea surface temperature during these 40 years in the northwest Pacific.
- It shows how global warming is responsible for making cyclones stronger, and thus increasing the chances of the Fujiwhara effect.
- The occurrence of the Fujiwhara Effect makes cyclones more unpredictable due to their rapid intensification, carrying of more rain and newer ways of moving over warming oceans.
- In the case of typhoons Parma and Melor in 2009, it became extremely difficult for forecasters to track the movement or intensity of either of the storms, especially Parma, and provide people with an early warning because of the Fujiwhara interaction between the two storms.
- In April 2021, a similar event happened in the Indian Ocean, when cyclone Seroja interacted with cyclone Odette just off the coast of Western Australia gaining strength and moving in uncharted ways.
- Seroja became a unique storm because the north-western coast of Australia is prone to cyclones while the south-western part hit by the cyclone does not get much storm activity.
NO COLLATED DATA
- There is no collated dataset.
- There is no worldwide accepted technique or recording agency dedicated to recognising and collecting the cases of the Fujiwhara effect as these are rare events and tough to assess.