What controls the climatology of severe local storms?
Severe thunderstorms are local-scale phenomena that present significant risk to life and property through hazards including tornadoes, hail, and wind. While the present distribution of these storms has been well documented, I am interested in gaining a better understanding of the theoretical basis of their climatology, and how it might vary over time.
A supercell thunderstorm near Burwell, Nebraska, June 16, 2014 (NOAA/Gabe Garfield)
Specifically, my research approaches the interface of severe convection and climate from a thermodynamic perspective by examining convective available potential energy (CAPE). The severity of thunderstorms over the continents is constrained by the magnitudes of transient peaks in this thermodynamic property of the environment. By examining the sources of CAPE, and by constructing a theoretical model for its magnitude, we can begin to answer important questions about long-term trends and interannual variability of severe local storms, and their associated risk.
Below: An animation of the global CAPE field for the entire year 2011, from the NOAA-CIRES 20th Century Reanalysis V2c. Note that the most extreme values of CAPE only occur briefly, and only in certain parts of the world. The dependence of these extreme peak CAPE occurrences on climatological parameters of the environment is the focus of my research.
Publications
Agard, V., & Emanuel, K. (2017). Clausius–Clapeyron Scaling of Peak CAPE in Continental Convective Storm Environments. Journal of the Atmospheric Sciences, 74(9), 3043-3054. https://doi.org/10.1175/JAS-D-16-0352.1
Agard, V. (2019). Surface fluxes as a primary source of CAPE in North American severe weather environments, submitted.