An investigation of the internal structure of the thunderstorm outflow with particular attention to multiple surges

Diana Lynn Klingle, Purdue University

Abstract

Thunderstorm outflows and gust fronts have been the focus of much recent research. The motivation for this prior research was to investigate the role of the gust front in maintaining the parent storm or to identify gust front signatures in Doppler radar data for use in automatic detection algorithms. This study focuses on the features within the outflow known as multiple surges. Concise definitions of multiple and secondary surges are formulated. Data from previously published outflow cases are compiled and some simple statistics are applied in an attempt to characterize multiple surges. Proposed causative mechanisms of multiple surges are also discussed. Three case studies are presented to investigate the causes of multiple surges. The first case study deals with a pulsating downdraft. The second case considers undulations along the top of the outflow boundary and a conceptual model is developed. The growth and dissipation of many cells within a single thunderstorm and the manner in which multiple surges are produced by this mechanism are examined in the third case. This work clearly shows that a variety of mechanisms can produce multiple surges. Some mechanisms are related to the parent storm (such as the pulsating downdraft) and some are related to processes, such as turbulent mixing, that affect the outflow.

Degree

Ph.D.

Advisors

Snow, Purdue University.

Subject Area

Atmosphere

Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server
.

Share

COinS