What Would Happen to Superstorm Sandy under the Influence of a Substantially Warmer Sea Surface Temperature in a Future Climate?

Hurricane Sandy, often referred to as Superstorm Sandy (SS), was the most destructive hurricane of the 2012 hurricane season, wreaking havocs along the eastern Atlantic seaboard from Florida to New York.  It was also the second most costly hurricane in United States history, with damages estimated at over $68 billion dollars. Given the unique occurrence and the enormity of its societal impacts, it is of great scientific and societal interests to know or to anticipate what can we expect from SS-like storms in a future warmer climate, to better inform and provide guidance for future mitigation strategies.  

Using ensemble numerical simulations with the NASA-Unified Physics Weather Research Forecast (NU-WRF) model and present-day atmospheric initial and boundary conditions, we have investigated possible responses of Sandy-like superstorms under the influence of warmer SST in a double-CO₂ climate, as projected by CMIP5 ensemble models.  We find that the responses bifurcate into two groups.  In the first group, storms are similar to present-day SS from genesis, storm track to extratropical transition, except they propagate faster, and are much stronger, with maximum wind destructive power increased by 50-80%, and heavy rain increased by 30-50%.     In the second group, storms have longer exposure time to the Atlantic warm pool, and amplify to super-hurricane strength over the interior of the warm pool, with peak destructive power increased by 100-160%, and heavy rain stronger by 70-180%.  However, unlike present-day SS, these second group of storms after exiting the warm pool, re-curve northeastward out to sea, subsequently interact with the developing mid-latitude storm by mutual amplitude modulation, via counter-clockwise rotation around each other.  The remnant of tropical storm eventually amplifies into a severe Northeastern coastal storm with landfall over the extreme northeastern regions from Maine to Nova Scotia.  The potential societal impacts of these two scenarios will be discussed.