Wed. Mar. 1st

1
QUANTIFYING THE NEAR-SURFACE WINDS IN TORNADOES
A COMBINED RADAR-MODELING APPROACH
Karen A. Kosiba Purdue University Dept. of
Earth Atmospheric Sciences
Abstract Tornadic winds within the lowest few
tens of meters above ground level (AGL) directly
impact life and property unfortunately this
region of the tornado is least understood. Due
to the intermittent and destructive nature of
tornadoes, obtaining measurements of a tornados
wind field, in particular within these lowest few
tens of meters AGL, can be a formidable task.
Further, numerical models used to study tornadic
flow are constrained by idealized boundary
conditions that do not detail the rapidly
evolving, complex flow actually observed in
tornadoes. It is in this light that a combined
radar-modeling approach has been developed to
investigate and quantify the three-dimensional
winds in this most hazardous region. This
radar-modeling approach uses low-level mobile
Doppler radar observations of tornadoes to
constrain a large-eddy simulation (LES) of the
tornado vortex. Collection of the radar data
during the ROTATE (Radar Observations of
Tornadoes and Thunderstorm Experiment) field
programs, the theory behind large-eddy
simulations, and results from the 12 May 2004
Harper, KS tornado will be the focus of this
talk.

• Wed. Mar. 1st