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Extreme Pacific sea level events to double in future
http://www.hawaii.edu/news/2015/09/25/extreme-pacific-sea-level-events-to-double-in-future/[font face=Serif][font size=5]Extreme Pacific sea level events to double in future[/font]
September 25, 2015 | Gisela Speidel
[font size=3]Many tropical Pacific island nations are struggling to adapt to gradual sea level rise stemming from warming oceans and melting ice caps. Now they may also see much more frequent extreme interannual sea level swings. The culprit is a projected behavioral change of the El Niño phenomenon and its characteristic Pacific wind response, according to recent computer modeling experiments and tide-gauge analysis by scientists Matthew Widlansky and Axel Timmermann at the International Pacific Research Center, University of Hawaiʻi at Mānoa, and their colleague Wenju Cai at Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia.
During El Niño, warm water and high sea levels shift eastward, leaving in their wake low sea levels in the western Pacific. Scientists have already shown that this east-west seesaw is often followed six months to a year later by a similar north-south sea level seesaw with water levels dropping by up to one foot (30 cm) in the Southern Hemisphere. Such sea level drops expose shallow marine ecosystems in South Pacific Islands, causing massive coral die-offs with a foul smelling tide called taimasa (pronounced |kai’ ma’sa|) by Samoans.
…
From our previous work, we know that toward the end of a very strong El Niño event, the tide-gauge measurements around Guam quickly return to normal reflecting the east-west seesaw, but those near Samoa continue to drop as a result of the lagging north-south seesaw,” explains Widlansky. “During these strong events, the summer rainband over Samoa, called the South Pacific Convergence Zone, shifts toward the equator and alters the trade winds and ocean currents which in turn change the sea level.”
“The next logical step in our work was to understand how future changes in winds, projected by most climate models, will impact the interannual swings in sea level,” recalls Timmermann. “We noted a trend in greater variability and were surprised at first to find not only more frequent and prolonged drops in sea level, but also more frequent high sea level events. This will further increase the risk of coastal inundations.”
…[/font][/font]
September 25, 2015 | Gisela Speidel
Extreme low sea levels occurred during August in parts of the western Pacific associated with the ongoing strong El Niño. Data from AVISO satellite measurements. (credit: Widlansky, et al., 2015)
[font size=3]Many tropical Pacific island nations are struggling to adapt to gradual sea level rise stemming from warming oceans and melting ice caps. Now they may also see much more frequent extreme interannual sea level swings. The culprit is a projected behavioral change of the El Niño phenomenon and its characteristic Pacific wind response, according to recent computer modeling experiments and tide-gauge analysis by scientists Matthew Widlansky and Axel Timmermann at the International Pacific Research Center, University of Hawaiʻi at Mānoa, and their colleague Wenju Cai at Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia.
During El Niño, warm water and high sea levels shift eastward, leaving in their wake low sea levels in the western Pacific. Scientists have already shown that this east-west seesaw is often followed six months to a year later by a similar north-south sea level seesaw with water levels dropping by up to one foot (30 cm) in the Southern Hemisphere. Such sea level drops expose shallow marine ecosystems in South Pacific Islands, causing massive coral die-offs with a foul smelling tide called taimasa (pronounced |kai’ ma’sa|) by Samoans.
…
From our previous work, we know that toward the end of a very strong El Niño event, the tide-gauge measurements around Guam quickly return to normal reflecting the east-west seesaw, but those near Samoa continue to drop as a result of the lagging north-south seesaw,” explains Widlansky. “During these strong events, the summer rainband over Samoa, called the South Pacific Convergence Zone, shifts toward the equator and alters the trade winds and ocean currents which in turn change the sea level.”
“The next logical step in our work was to understand how future changes in winds, projected by most climate models, will impact the interannual swings in sea level,” recalls Timmermann. “We noted a trend in greater variability and were surprised at first to find not only more frequent and prolonged drops in sea level, but also more frequent high sea level events. This will further increase the risk of coastal inundations.”
…[/font][/font]