Dual-Doppler analysis of the 17 June 1997 bow echo over southeast Texas

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references (leaves 64-69).Issued also on microfiche from Lange Micrographics.Eight volumes of radar data were used for the dual-Doppler analysis of a bow echo that occurred over southeast Texas on 17 June 1997 during the Texas A&M University Convection and Lightning experiment (TEXACAL). The bow echo formed along a stationary cold front and progressed quickly eastward through the dual-Doppler network. The storm system portrayed many features similar to conceptual models of bow echoes, such as a strong rear inflow jet which forms early and strengthens and extends rearward throughout the lifecycle of the bow echo. Distinct cyclonic and anticyclonic mesoscale vortices form along the northern and southern portions of the bow echo, respectively, in association with the strengthening rear inflow jet. One feature not shown in conceptual models of bow echoes however is a distinct, smaller-scale, cyclonic vortex present along the northern front edge of the bow echo. This vortex seems to have formed from the tilting and subsequent stretching of vorticity generated along an outflow boundary, associated with previous convection, which is intersecting the northern portion of the bow echo. This vortex is present before the mesoscale vortices become noticeable and seems to be driving the nearby flow field, particularly the rear inflow jet, associated with the bow echo. The fact that this vortex tends to be the reason for the bowing of this particular storm system and dominates its overall evolution highlights the importance of boundaries on bow echoes. This feature has yet to be reproduced by numerical models because of the homogeneous environment assumption which eliminates any kind of boundary in the environment around the bow echo. To Gary, Linda, Janice and Amber Moncla and Gail Brady ACKNOWLEDGMENTS Many thanks to my committee members in particular my committee chair and academic advisor Michael Biggerstaff whose financial support and scientific guidance helped make this research possible. I am also grateful for the many helpful discussions and comments from Josh Santarpia and Dan Jamieson. Much appreciation is given to the rest of the Mesoscale Research Group at Texas A&M University in particular Gordon Carrie for his help with data processing. I would also like to thank my girlfriend Gail Brady for her emotional and financial support as well. This research was supported by the National Aeronautical and Space Administration under grants NAG5-4776 and NAG5-9697