IN SITU, DOPPLER RADAR, AND VIDEO OBSERVATIONS OF THE INTERIOR STRUCTURE OF A TORNADO AND THE WIND-DAMAGE RELATIONSHIP

摘要

THERE ARE FEW NEAR-GROUND OBSERVATIONS INSIDE TORNADOES. Tornadoes cause substantial loss of life and property every year, primarily in the central regions of North America. In 2011, several hundred people lost their lives and over 20 billion dollars(all values are in current U.S. dollars) of damage occurred as the result of several tornado outbreaks that impacted populated regions (Lott et al. 2012; FEMA 2012). Verification of near-surface tornado wind models (Lewellen 1976; Church et al. 1979; Rotunno 1979; Davies-Jones 1986;Lewellen et al. 1997; Lewellen et al. 2000; Lewellen and Lewellen 2007a,b; Snow 1982; Fiedler and Rotunno 1986) and the relationship between these winds and structural damage requires reliable measurements near the ground, in the core flow region of tornadoes. In recent years, mobile Doppler radars have been central to mapping the three-dimensional wind structure in many tornadoes from as low as 30 m above ground level (AGL) to above 1 km AGL. These have allowed the documentation of the evolution and structure of tornadic winds including the prevalence of axial down-drafts aloft, low-level convergence, and the existence of multiple vortices (Wurman et al. 1996; Wurman and Gill 2000; Bluestein et al. 2003, 2004; Wurman and Alexander 2005; Wurman and Samaras 2004; Bluestein et al. 2007; Wurman et al. 2007a,b,c; Wurman 2002; Kosiba et al. 2008; Lee and Wurman 2005; Tanamachi et al. 2007; Wurman and Kosiba 2008; Wurman et al. 2008; Kosiba and Wurman 2010; Wurman et al. 2010; Wurman and Kosiba 2013, manuscript submitted to Wea. Forecasting). However, the structure of tornadic winds below -30 m AGL has not been well quantified. Radar measurements, with few exceptions (Wurman