What Registers As A 500 Year Storm
Hurricane Sandy's devastating storm track is a rare one amidst hurricanes; a new statistical analysis estimates that the runway of the storm — which took an unusual left-hand turn in the Atlantic before slamming into the East Declension — has an average probability of happening only in one case every 700 years.
"The particular shape of Sandy's trajectory is very peculiar, and that's very rare, on the order of one time every 700 years," said Timothy Hall, a senior scientist at the NASA Goddard Institute for Space Studies who co-authored the report. That ways that in whatsoever item year, the hazard of such a storm track happening is 0.14 percent.
The storm's nigh-perpendicular strike on the coast was a major factor in the severe flooding seen in New York, New Jersey and other nearby states, Hall added. Only the rareness of the tempest'south rail doesn't mean that the declension is condom from other severe storms. [Bailiwick of jersey Shore: Earlier & Afterwards Hurricane Sandy]
"We don't want to lead with the misimpression that we don't take to worry, (that) it'southward going to be 700 years until nosotros have another surge. That's not truthful," Hall told LiveScience.
While Hall'southward initial enquiry, detailed in the May 28 effect of the journal Geophysical Research Messages, assumed a "steady state" organization in which climate is not changing, he and others are also studying how climate change influences hurricane tracks. Those studies will help decide if the rarity of paths similar the one Sandy took might change in a warming world.
Plotting the tempest track
Hurricane Sandy caused nigh 150 deaths, along with billions of dollars in damage when it hit the Caribbean and the U.S. Due east Coast in late October 2012. The storm'due south power came from a combination of factors, including its large size while out at sea and a full moon that made tides 20 percentage higher than normal, both of which ramped upward Sandy's storm surge.
Study researchers also pointed to conditions patterns that affected Sandy's track. A region of high pressure level blocked Sandy from taking a more common rail out over the western North Atlantic, forcing the storm into the coast. Sandy also interacted with a mid-level, depression-pressure arrangement in the atmosphere, which helped push the storm along its unusual track.
To report the rarity of Sandy'south track, Hall and his colleague, Columbia Academy mathematician Adam Sobel, had to apply a model to generate synthetic tropical cyclones. The researchers could not rely on previously recorded data, as Sandy'south trajectory and almost-direct bear on on New Jersey was unprecedented in the historical record.
The researchers' statistical model generated millions of these constructed hurricanes, which were then used to determine rates for landfall. While Sandy was not a tropical storm by the fourth dimension information technology hit the United states, the model focused on storms that originated equally tropical storms, regardless of their status when they made landfall.
Most of the tracked landfalls in the model grazed the coast before veering out into the Atlantic. Sandy, past dissimilarity, hit the coast at an bending of just 17 degrees from perpendicular, almost perfectly crisscrossing the typical tempest track.
"The sustained winds towards the coast from the directly path is continually pushing a wall of water onto the coast, and y'all tin become a greater surge magnitude," compared to more than typical in-land winds sweeping along the declension, Hall said.
This big surge pushed way more h2o onto streets than might be expected in Manhattan, for example. The peak water level (the surge plus the tide) at the Battery, Manhattan'southward southern tip, was 14 feet (four.28 meters) higher up the boilerplate low tide level, according to National Oceanic and Atmospheric Assistants figures cited in the paper.
Climate change the big dubiety
As for how probable some other Sandy would be in a earth altered by climate change, that question is still upwards in the air.
The consensus from the all-time global climate models is that the intensity of hurricanes globally will increment in a warmer climate, although fewer storms will occur overall. However, a recent report suggests that both frequency and intensity will increase. Models for individual regions such equally the North Atlantic are less reliable, nonetheless, making it hard to forecast changes in hurricane hazards in specific regions of the coast.
Even less certain are changes in hurricane tracks due to climate. Every bit the Arctic warms upwards, some scientists propose the temperature deviation between higher and lower latitudes will drop and weaken the jet stream, making storms less likely to follow this stream out into the Atlantic. However, this prediction has non been corroborated in other studies, Hall said.
The effect of surges, though, is very likely to increase in the side by side 100 years, by and large due to higher body of water levels. Warming oceans and melting glaciers will raise bounding main levels, worsening storm surges in the future, Hall said. In add-on, warmer air holds more water vapor, resulting in more rainfall from potent storms, which could exacerbate flooding, another common upshot with tropical storms.
A February report in the journal Nature Climate change predicted that, by the end of the century, a typical "500-year" tempest surge in New York would actually happen anywhere between once every fifty years to once every 240 years. [Hurricane Sandy: A Glimpse at New York'southward Scary Future]
A separate written report published in the journal Chance Analysis said that New York is among the cities most prone to coastal flooding. The current average flood harm estimate is betwixt $59 million and $129 million a yr. Harm from a 1-in-500-twelvemonth tempest surge would be between $5 billion and $11 billion. The total damage from Sandy to just New York and New Bailiwick of jersey was $71 billion co-ordinate a Nov 2012 Reuters article.
This story has been updated to right the percentage take chances of having a storm like Sandy in a given year. Information technology is 0.14 pct, not 0.0014 percentage. Follow Elizabeth Howell @howellspace. Follow united states of america @livescience, Facebook and Google+. Original article on LiveScience.
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What Registers As A 500 Year Storm,
Source: https://www.nbcnews.com/sciencemain/hurricane-sandy-called-1-700-year-event-6C10654786
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