Study Offers New Insight on Hurricane Intensification
UM Rosenstiel School researchers analyze 2012 hurricane in Gulf of Mexico
November 09, 2016
MIAMI—In a new study, researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science showed the first direct observations of hurricane winds warming the ocean surface beneath them due to the interactions with currents from an underlying warm-water whirlpool. These new findings are critical to help improve hurricane forecasting models.
In 2012, UM Rosenstiel School researchers, in collaboration with scientists from NOAA’s Atlantic Oceanographic and Meteorological Laboratory, deployed a total of 376 airborne sensors during six NOAA hurricane hunter aircraft flights conducted before, during, and after the passage of Isaac over the eastern Gulf of Mexico. The suite of highly specialized instruments collected critical wind, temperature, and humidity data on the hurricane, as well as measured ocean conditions, such as temperature, salinity, and current, along the storm’s predicted track.
“We directly observed that underneath a hurricane there is not necessarily a cooling environment when the storm moves over a pre-existing warm oceanic whirlpool,” said UM Rosenstiel School researcher Benjamin Jaimes.
The study suggests that the complex interactions between hurricane winds and surface ocean currents can pull warm surface water from areas away from the storm’s eye. These warmer waters provide a warm and moist environment underneath the hurricane that can facilitate its intensification.
“Measuring and understanding air-sea interactions in these complex environments is critical to improve hurricane intensity forecasting models,” said UM Professor of Ocean Sciences Nick Shay, a senior author of the study.
These warm-water whirlpools, or eddies, are created when they separate from the Gulf of Mexico’s Loop Current. Warm-water eddies were also responsible for Hurricane Katrina’s rapid intensification in the Gulf of Mexico.
In 2013, Isaac intensified in the Gulf of Mexico to become an 80 mph (130 km/h) category 1 hurricane, making landfall along the coast of Louisiana near the mouth of the Mississippi River. The storm was estimated to have caused $2.39 billion in damage along its track.
In a separate study published last year the research team showed how a downwelling of warm waters deepened the storm’s fuel tank for a rapid intensification toward hurricane status.
The study, titled “Observed air-sea interactions in tropical cyclone Isaac over Loop Current mesoscale eddy features,” was published online in the journal Dynamics of Atmospheres and Oceans. UM Rosenstiel School researcher Jodi Brewster was a coauthor on the study.
The research is part of a three-year NASA-funded project "Wind-driven upwelling and vertical mixing in mesoscale eddies from a global perspective” to analyze data from several past hurricanes (NASA grant NNX15AG43G). The Gulf of Mexico Research Initiative sponsored Deep-C consortium also sponsored the study (Gulf of Mexico Research Initiative grant SA1212GoMRI008).
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About the University of Miami’s Rosenstiel SchoolThe University of Miami is one of the largest private research institutions in the southeastern United States. The University’s mission is to provide quality education, attract and retain outstanding students, support the faculty and their research, and build an endowment for University initiatives. Founded in the 1940’s, the Rosenstiel School of Marine & Atmospheric Science has grown into one of the world’s premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life. For more information, visit: www.rsmas.miami.edu.
Observed air-sea interaction during the intensification of tropical storm Isaac into a hurricane on August 28, 2012, over a warm oceanic whirlpool (point A) and cool oceanic cyclone (point B). These contrasting upper-ocean interactions impacted the moisture fluxes into Isaac and ensuing storm intensity.
Credit: Benjamin Jaimes, UM Rosenstiel School of Marine and Atmospheric Science