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This research seeks to answer the basic question of how current-day extreme tornadic storm events might be realized under future anthropogenic climate change. The pseudo global warming (PGW) methodology was adapted for this purpose. Three contributions to the CMIP5 archive were used to obtain the mean 3D atmospheric state simulated during May 1990-99 and May 2090-99. The climate change differences (or Ds) in temperature, relative humidity, pressure, and winds were added to NWP analyses of three high-end tornadic storm events, and this modified atmospheric state was then used for initial and boundary conditions for realdata WRF Model simulations of the events at high resolution. Comparison of an ensemble of these simulations with control simulations (CTRL) facilitated assessment of PGW effects.
In contrast to the robust development of supercellular convection in each CTRL, the combined effects of increased convective inhibition (CIN) and decreased parcel lifting under PGW led to a failure of convection initiation in many of the experiments. Those experiments that had sufficient matching between the CIN and lifting tended to generate stronger convective updrafts than CTRL, although not in proportion to the projected higher levels of convective available potential energy (CAPE) under PGW. In addition, the experiments with enhanced updrafts also tended to have enhanced vertical rotation. In fact, such supercellular convection was even found in simulations that were driven with PGW-reduced environmental wind shear. Notably, the PGW modifications did not induce a change in the convective morphology in any of the PGW experiments with significant convective storminess.
ABSTRACT
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1. Introduction
A persistent uncertainty in climate change assessments to date regards how the frequency and intensity of local, high-impact convective storms might be affected by the global radiative forcing due to anthropogenically enhanced greenhouse gas concentrations. Much of this uncertainty can be attributed to the fact that convective storms as well as their attendant hazards have spatial scales that fall well below the effective resolution of typical global and even regional climate models.
As first demonstrated by Trapp et al. (2007), Del Genio et al. (2007), and Marsh et al. (2007), this modelresolution issue can be partly overcome through the use of environmental proxies-that is, convective-storm occurrences represented through quantifications of the larger-scale distributions of temperature, humidity, and...