New statistical methods have revealed what's in store for the U.S. in terms of storm intensity and size. Researchers from the University of Chicago and Argonne National Laboratory predict that though storms in the U.S. will be more powerful, they will have a smaller radius.
In a research published in Journal of Climate, the new approach was used to identify and track storm features in both observational weather data and new high-resolution climate modeling simulations.
"Climate models all predict that storms will grow significantly more intense in the future, but that total precipitation will increase more mildly over what we see today," according to senior author Elisabeth Moyer. An associate professor of geophysical sciences at the University of Chicago, she is also a co-director of the Center for Robust Decision-Making on Climate and Energy Policy. "By developing new statistical methods that study the properties of individual rainstorms, we were able to detect changes in storm frequency, size, and duration that explain this mismatch."
Climate change has brought on increased temperatures and changes in precipitation patterns and has also resulted in more droughts and flooding. Most climate models predict that high levels of atmospheric carbon will increase precipitation intensity by an average of approximately 6 percent per degree temperature rise. More recently, high-resolution simulations have begun to approach weather-scale, but analytic approaches had not yet evolved to make use of that information and evaluated only aggregate shifts in precipitation patterns instead of individual storms.
Moyer and her team developed new methods to analyze rainstorms in observational data or high-resolution model projections. The researchers were able to study results of new ultra-high-resolution (12 km) simulations of U.S. climate performed with the Weather Research and Forecasting Model at Argonne National Laboratory.
According to their findings, individual storms covered smaller land areas during the summer. The same was observed for winter months, but with storms lessening in terms of frequency and duration.
"While our results apply to only one model simulation, we do know that the amount-intensity discrepancy is driven by pretty basic physics. Rainstorms in every model, and in the real world, will adjust in some way to let intensity grow by more than total rainfall does," Moyer shared. "Most people would have guessed that storms would change in frequency, not in size. We now have the tools at hand to evaluate these results across models and to check them against real-world changes, as well as to evaluate the performance of the models themselves."