Jul 5, 2016

The Realization of Extreme Tornadic Storm Events under Future Anthropogenic Climate Change

by
Robert J. Trapp and Kimberly A. Hoogewind
,
American Meteorological Society
  • Seeks to answer the basic question of how current-day extreme tornadic storm events might be realized under future anthropogenic climate change
  • Adapts the pseudo global warming (PGW) methodology for this purpose
    • The PGW method is used to perform time-sliced downscaling of climate changes projected by global climate models (GCMs). Downscaling is the process of taking information known at large scales to make predictions at local scales using models and statistics. It's called a 'timeslice' experiment because it only simulates two slices of time, one for the present and one for the future.
  • Uses models to simulate the mean atmospheric state during May 1990–99 and May 2090–99
  • Considers the climate change differences (or Δs) in temperature, relative humidity, pressure, and winds
  • Finds that the combined effects of increased convective inhibition and decreased parcel lifting under pseudo global warming led to a failure of convection initiation in many of the experiments (in contrast to the robust development of supercellular convection in each control simulation)
  • Finds that experiments that had sufficient matching between the convective inhibition and lifting tended to generate stronger convective updrafts than control simulations, although not in proportion to the projected higher levels of convective available potential energy (CAPE) under PGW
  • Finds the experiments with enhanced updrafts also tended to have enhanced vertical rotation
  • Finds such supercellular convection even in simulations that were driven with PGW-reduced environmental wind shear
  • Finds that the PGW modifications did not induce a change in the convective morphology in any of the PGW experiments with significant convective storminess