Tornado Research Papers
Introduction and background
Tornadoes are among the most destructive natural hazards to human life and property. In the United States, approximately 1,253 tornadoes occur every year (NCDC 2015) causing an average of 50 fatalities per year and $400 million in annual economic losses (Brooks and Doswell 2000; Boruff et al. 2003; Brooks and Dotzek 2008). In recent years, significant advances have been made toward understanding and measuring the atmospheric factors influencing tornado genesis (Brooks et al. 2003), which can assist in disseminating warning information to reduce risk. Yet despite now having a better understanding of tornado formation and the conditions needed for genesis, it remains extremely difficult to predict exactly where …show more content…
All other links are zero. In the standardized version of the statistic used here, the target region i is included in the computation of the statistic. Therefore,
??? ? 0. The variables ?? and s are the sample mean and standard deviation of the observed set of xi, respectively. Gi* will produce high values along with a high positive z-score when there is a dominant pattern of high values near other high values and will produce low values when there is clustering of low values (Rogerson and Yamada 2008). The benefit of the Gi* statistic over other commonly used measures of global spatial association, such as Moran?s I (Moran 1948) is that it can find both ?hot? and ?cold? spots.
The hot spot results (Fig. 2) show several interesting patterns of touchdown occurrence.
First, a large, prominent cluster stretches from Denver across eastern Colorado, Nebraska, Kansas, Oklahoma, Arkansas, and North Texas. This ?Tornado Alley? cluster does not approach the Appalachian region. While the mean center of tornado activity is located in Missouri …show more content…
These biases were reduced by ensuring that every county was analyzed with at least one neighbor, and larger counties primarily occur in western states where tornado activity is reduced. Edge effects can also occur for areas that do not have physical neighbors (e.g., counties along the coast), but since most of the tornado activity in the United States occurs inland (Goliger and Milford 1998), edge effects are limited.
Lastly, the Fujita and Enhanced Fujita scales used to assign magnitude values to tornadoes are damage-rating systems, not intensity-rating systems (Farney and Dixon 2015). While damage and intensity are highly correlated, there can be differences in magnitude depending on the environment through which the tornado passed. For example, tornadoes in urban areas are more likely to obtain higher F-scale (or EF-scale) ratings than rural areas because the potential for damage is greater (Doswell and Burgess 1988). Aside from the lowest magnitude tornadoes, we did not find significant differences between different magnitudes for the environmental and land cover variables, so this discrepancy is not likely impacting our analysis
Tornadoes are among the most destructive natural hazards to human life and property. In the United States, approximately 1,253 tornadoes occur every year (NCDC 2015) causing an average of 50 fatalities per year and $400 million in annual economic losses (Brooks and Doswell 2000; Boruff et al. 2003; Brooks and Dotzek 2008). In recent years, significant advances have been made toward understanding and measuring the atmospheric factors influencing tornado genesis (Brooks et al. 2003), which can assist in disseminating warning information to reduce risk. Yet despite now having a better understanding of tornado formation and the conditions needed for genesis, it remains extremely difficult to predict exactly where …show more content…
All other links are zero. In the standardized version of the statistic used here, the target region i is included in the computation of the statistic. Therefore,
??? ? 0. The variables ?? and s are the sample mean and standard deviation of the observed set of xi, respectively. Gi* will produce high values along with a high positive z-score when there is a dominant pattern of high values near other high values and will produce low values when there is clustering of low values (Rogerson and Yamada 2008). The benefit of the Gi* statistic over other commonly used measures of global spatial association, such as Moran?s I (Moran 1948) is that it can find both ?hot? and ?cold? spots.
The hot spot results (Fig. 2) show several interesting patterns of touchdown occurrence.
First, a large, prominent cluster stretches from Denver across eastern Colorado, Nebraska, Kansas, Oklahoma, Arkansas, and North Texas. This ?Tornado Alley? cluster does not approach the Appalachian region. While the mean center of tornado activity is located in Missouri …show more content…
These biases were reduced by ensuring that every county was analyzed with at least one neighbor, and larger counties primarily occur in western states where tornado activity is reduced. Edge effects can also occur for areas that do not have physical neighbors (e.g., counties along the coast), but since most of the tornado activity in the United States occurs inland (Goliger and Milford 1998), edge effects are limited.
Lastly, the Fujita and Enhanced Fujita scales used to assign magnitude values to tornadoes are damage-rating systems, not intensity-rating systems (Farney and Dixon 2015). While damage and intensity are highly correlated, there can be differences in magnitude depending on the environment through which the tornado passed. For example, tornadoes in urban areas are more likely to obtain higher F-scale (or EF-scale) ratings than rural areas because the potential for damage is greater (Doswell and Burgess 1988). Aside from the lowest magnitude tornadoes, we did not find significant differences between different magnitudes for the environmental and land cover variables, so this discrepancy is not likely impacting our analysis