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20 September 2020.
Introduction:
On September 18 2020, Greece was impacted by a so-called Medicane (MEDIterranean hurriCANE), by the name of Ianos bringing high winds and waves and torrential rain and the risk of flooding.
What are Medicanes and how they differ from tropical cyclones?
- Simply put hurricanes occurring in the Mediterranean are called Medicanes.
- These are extra-tropical hurricanes observed over the Mediterranean Sea.
- They occur more in colder waters than tropical cyclones, hurricanes and typhoons.
- Hence, the cores of these storms are also cold, as compared to the warm cores of tropical cyclones.
- Warmer cores tend to carry more moisture (hence rainfall), are bigger in size and have swifter winds.
- The main societal hazard posed by Medicanes is through life-threatening torrential rains and flash floods.
- They are likely to become more common due to human- induced – climate changes.
Reason for increased frequency of Medicanes:
- Global warming.
- Increased temperature of the Mediterranean Sea causes the cyclones to take more tropical appearance.
- Increase in SST increases the wind speed of the storms and cause heavy rainfall.
- Earlier the Medicanes were common only in Mediterranean Sea but in the past two decades they have formed over Black sea.
- Two such storms were formed recently in 2005 an 2012.
- Mediterranean Sea is dry and cyclonic storms do not form easily and are hard to detect.
- However, with the increase in the sea surface temperature, Medicanes have increased and this has caused flooding in France, Italy and Spain.
About effect of ENSO on Medicanes:
- ENSO is El Nino Southern Oscillation that is developed over the Pacific Ocean.
- The 2020 year according to the World Meteorological Organisation is a La Nina year.
- Usually La Nina reduces the number of hurricanes. But this year in spite of a mild La Nina in the Pacific, hurricanes are very active.
- This means that the impacts of El Nino southern oscillation is getting modulated due to global warming of all oceans including the Mediterranean.
- This is why in spite of a mild La Nina, the number of Mediterranean cyclones have increased.