Summary

Using both a GIS and literature-based analyses of current conditions we developed a model of current TC activity for the NA basin, in which TCs are latitudinally "fixed" between the ITCZ to the south and the BH to the north, with changes in the general atmospheric circulation, as proxied by the NAO Index values, resulting in the smearing of track location and landfall across the NA.

Evidence suggests that the coordinated movement of the ITCZ and the BH has existed through the Holocene, controlled primarily by the pole-equator temperature gradient. Changes in that gradient, ultimately driven by orbital factors, have resulted in latitudinal movement of this integrated atmospheric structure on a number of time scales. As part of this structure the TC zone has migrated north and south over the Holocene in rough parallel with the ITCZ. From — 8000 BP on, sedimentary evidence for the migration of the zone of maximum hurricane landfall has potentially been preserved. Hindcasts, based on the proxy migration record of the ITCZ, the southern edge of the structure, suggest that the zone of maximum TC activity moved significantly to the

1. north from -8000-4000 BP and 1100-600 BP

2. south from -4000-2400 and 400-200 BP.

By providing proxy paleo-strike records, paleotempestology studies in the northern and southern edges of the TC zone provide a method of evaluating the validity of the model.

Acknowledgments This research was funded by National Science Foundation Graduate Research Fellowship, LSU Board of Regents Fellowship, (TAM), and National Science Foundation Doctoral Dissertation Research Improvement Grant (TAM and JTK). We thank Kam-biu Liu for his guidance and advice. The work was improved due to the comments of an anonymous reviewer.

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