No likelihood that Sandy-like storms will increase in future per "best models available," Kerry Emanuel, PNAS study, August 2013

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8/2/13, "Model projections of atmospheric steering of Sandy-like superstorms," pnas.org, edited by Kerry Emanuel, MIT

Abstract:

"Either Sandy was an extremely rare event or climate change has increased the odds so that the return period reported by Hall and Sobel (1) is an overestimate. We address the latter question here by focusing on how the frequency of the large-scale flow patterns that gave Sandy its anomalous path will change in a warming climate."...(parag. 4)

"Given that these unusual atmospheric conditions were crucial to steer Sandy, the obvious question is: will these conditions change in the future? In other words, will changes in the large-scale flow patterns make westward steering of transitioning Atlantic tropical cyclones more likely, thus increasing the probability of landfall of any such storms whose tracks bring them near the coast of the northeast United States?...(parag. 9)

"The best models available offer no support for the conclusion that blocking frequency or westward steering will increase in the future."...(parag. 14)

Hall and Sobel, 5/28/13: "We calculate that under long-term average climate conditions, a hurricane of Sandy's intensity or greater (category 1+) makes NJ landfall at an angle at least as close to perpendicular as Sandy's at an average annual rate of 0.0014 yr^–1 (95% confidence range 0.0007 to 0.0023); i.e., a return period of 714 years (95% confidence range 435 to 1429)."

"Author Information

1. 1 NASA Goddard Institute for Space Studies, New York, New York, USA."

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Image: "Unlike the 10 other hurricanes that made landfall in the region shown since 1851 and typically grazed the coast, Hurricane Sandy barreled into New Jersey on a path (red) nearly perpendicular to the shoreline. Figure from the paper. ©AGU."
  

"Their results agree with two other studies that predicted hurricanes would impact Manhattan with Sandy’s 9-foot surge or greater once every 400-800 years. “We had completely different models and were looking at different things, but our results overlapped,” Hall said. “This points to a very unusual storm.”"

6/3/13, "Hurricane Sandy took highly unusual path, but climate change doesn’t get the blame – yet," blogs.AGU.org, by Sarah Charley
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"We calculate that under long-term average climate conditions, a hurricane of Sandy's intensity or greater (category 1+) makes NJ landfall at an angle at least as close to perpendicular as Sandy's at...a return period of 714 years."...

5/28/13, "On the impact angle of Hurricane Sandy's New Jersey landfall," Geophysical Research Letters, AGU, Timothy M. Hall (1) and Adam H. Sobel (2)

"Abstract"

"[1] Hurricane Sandy's track crossed the New Jersey coastline, at an angle closer to perpendicular than any previous hurricane in the historic record, one of the factors contributing to record-setting peak-water levels in parts of New Jersey and New York. To estimate the occurrence rate of Sandy-like tracks, we use a stochastic model built on historical hurricane data from the entire North Atlantic to generate a large sample of synthetic hurricanes. From this synthetic set we calculate that under long-term average climate conditions, a hurricane of Sandy's intensity or greater (category 1+) makes NJ landfall at an angle at least as close to perpendicular as Sandy's at an average annual rate of 0.0014 yr^–1 (95% confidence range 0.0007 to 0.0023); i.e., a return period of 714 years (95% confidence range 435 to 1429)."

"Author Information

1. 1 NASA Goddard Institute for Space Studies, New York, New York, USA
2. 2 Department of Applied Physics and Applied Mathematics and Lamont-Doherty Earth Observatory, Columbia University, New York, New York, USA

^*Corresponding author: T. M. Hall, NASA Goddard Institute for Space Studies, New York, NY, USA."



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