Methods to rank and classify severe weather outbreaks
As geographic scatter initially was accounted for by using a latitude-longitude box for the median 50% of the latitudes and longitudes of the reports, days with large geographic scatter were ranked lower than days with a large number of reports over a relatively small, single region. However, days with multiple clusters of reports were counted as one event and were penalized by the original index technique. This is not desirable if distinct synoptic-scale systems were responsible for these separate clusters. A modification to the initial technique was developed using kernel density estimation, which allows for events to be considered by clusters of reports on a given day. The new method excludes events with large geographic scatter effectively, and includes multiple clusters of reports on a given day as separate events, as desired.
A final limitation was the arbitrary designation of events as 24-h periods. A technique is proposed to follow clusters of reports in short, adjoining time periods for consideration of outbreaks as single events with no time constraints. The technique allows for identification of multi-day outbreaks associated with individual synoptic-scale systems. This work will be used in future studies to study a large number of these events.
Supplementary URL: http://www.ejssm.org/ojs/index.php/ejssm/issue/view/19