Washington, Aug 13 : Global warming will decrease hurricane activity, but if formed they would be of very high intensity, says a group of researchers.
In the study, scientists have developed a new method for evaluating the frequency of hurricane formation in present and future tropical climates. In a study, Drs. David S. Nolan and Eric D. Rappin from the University of Miami's Rosenstiel School of Marine and Atmospheric Science have described the new method that may out do the computer models used for such studies.
Currently, most of the information about changes in hurricane frequency comes mostly from computer simulations of global climate.
However, the computer models used for these studies can only represent the coarsest features of hurricanes, thus casting doubt in their predictions of hurricane activity.
This new technique makes use of computer models with much more accurate representation of the processes that lead to hurricane formation, in the same way a digital image with more pixels allows for a more detailed photographic image.
The models are used to simulate the rate of hurricane development in tropical atmospheres with varying values of sea surface temperature and vertical wind shear (which is the extent to which wind speed and direction changes with height in the atmosphere).
These two variables - ocean temperature and wind shear -- are considered to be the two most important factors in predicting hurricane activity, both in operational forecasting and in consideration of climate change.
"We designed the computer simulations to show that as the ocean temperature increased, hurricanes would form more rapidly and easily, even in the presence of wind shear. Instead, we got exactly the opposite result. As the water temperature increased, the effectiveness of the wind shear in suppressing hurricane formation actually became greater," said Nolan, associate professor of Meteorology at the Rosenstiel School.
The simulations show that if in case hurricanes form, they become stronger in the warmer environments.
Taken together, these results indicate that in a global warming world, there would be less hurricanes, but those that do form could become stronger.
"The additional aspect that our method offers is a much more accurate picture of the process of tropical storm and hurricane formation, as compared to the global models," said Nolan.
The study is published in a recent issue of Geophysical Research Letters.