Policy / Systems / Technology

June 10, 2016

 

Discovery of Coastal Niño Phenomenon May Increase Accuracy of Climate Change Projections

Keywords: Climate Change Environmental Technology 

Photo: Sea
Image by kaboompics.

The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) announced on January 7, 2016, that it discovered a previously unidentified regional ocean-atmosphere coupled phenomenon off the coast of Dakar in West Africa. JAMSTEC named the phenomenon Dakar Niño/Niña, and further clarified the mechanism of coastal Niño phenomena, in addition to the large-scale phenomena such as El Niño and the Indian Ocean Dipole Mode. By incorporating the mechanism of these phenomena into prediction models, it may be possible to increase the accuracy of predicting climate changes that cause extreme weather events.

In the coastal region of Dakar, seawater is transported offshore by the rotation of the earth and trade winds that blow from the northeast throughout the year. This is counterbalanced by the upwelling of cold water from the deep ocean. This significant fluctuation in sea surface temperatures was known to have a large impact on the marine ecosystem some years, but the causes of this fluctuation had never been investigated until now.

A detailed analysis of data for the Dakar coastal area over the past 30 years made it possible to identify six warm events and five cold events. A warm event when the sea surface temperature rises is called Dakar Niño, whereas a cold event when the sea surface temperature falls is called Dakar Niña. The study group further identified an air-sea interaction in which sea-surface temperature variability caused by Dakar Niño/ Niña warms and cools the local atmosphere, creating a land-ocean atmospheric pressure difference, which produces coastal winds that affect the water temperature of the ocean surface, which in turn has an impact on the coastal winds.

Previously, JAMSTEC identified similar coupled ocean-atmosphere phenomena such as Ningaloo Niño/Niña and California Niño/Niña.

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