FUJIWHARA EFFECT

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Context

The occurrence and implications of the "Fujiwhara effect."

Details

• The United States West Coast has experienced unusual weather phenomena recently, including Hurricane Hilary.
• The National Hurricane Centre issued its first tropical storm watch for parts of Southern California due to this sub-tropical storm. Unusual weather events, like the "Fujiwhara effect," have been observed in the region.

Atmospheric Rivers and Fujiwhara Effect

• California witnessed an unusually wet winter with "atmospheric river" storms, carrying dense moisture in the atmosphere.
• The "Fujiwhara effect" occurs when two hurricanes or cyclones spin in the same direction and interact closely.
• These cyclones engage in an intense dance around a common center, with outcomes depending on their relative strengths.
• If one cyclone is stronger, it absorbs the weaker one. Similar-strength cyclones may merge or spin around each other before separating.
• Rarely, intense cyclones merging can form a mega cyclone with destructive potential.
• The phenomenon was first identified by Japanese meteorologist Sakuhei Fujiwhara in 1921 and observed in 1964 over the Pacific Ocean.

Outcomes Based on Cyclone Strength

Weaker Cyclone Absorption

• If one cyclone is significantly weaker than the other, it can get drawn into the circulation of the stronger cyclone.
• Eventually, the weaker cyclone is absorbed, and their individual identities are lost.

Similar-Strength Cyclones

• Cyclones of comparable strengths may either merge to form a larger cyclone or engage in a complex rotational dance.
• Their interaction results in unpredictable movements as they gravitate towards each other and exchange energy.

Intense Cyclone Merging

• In rare cases, two intense cyclones can merge, leading to the formation of a mega cyclone with heightened destructive potential.
• This merging amplifies their combined energy and can have severe consequences for coastal regions.

Historical Context and Discovery

• Identified by Japanese meteorologist Sakuhei Fujiwhara in 1921.
• The effect was first mentioned in Fujiwhara's 1921 paper.
• The phenomenon was observed over the western Pacific Ocean when Typhoons Marie and Kathy merged in 1964.

Impact and Observations

• In March 2023, the Bay Area and Southern California faced powerful winds and damage due to the Fujiwhara effect.
• Typhoon Hinnamnor and tropical storm Gardo exhibited the Fujiwhara effect, leading to casualties in South Korea.
• Hurricane scientist David Longshore noted that the effect might intensify the primary circulation of a system and make cyclonic systems harder to predict.

Relation to Climate Change

• Experts link the increasing frequency of the Fujiwhara effect to global warming and rising ocean temperatures.
• Ravi Shankar Pandey's research shows a 35% increase in typhoon strength in Taiwan between 1977 and 2016 due to rising sea surface temperatures.

https://indianexpress.com/article/explained/explained-climate/fujiwhara-effect-cyclones-dance-8905398/