EXAMINATION OF MESOSCALE FORCING OF A SWASH-ALIGNED, GRAVEL BARRIER FROM NOVA-SCOTIA

The possibility by which the retreat of a swash-aligned, gravel barrie r on Nova Scotia's Atlantic coast may be influenced by varying mesosca le time domains of differential process conditions is examined. Tide g auge data are used to generate definition of mesoscale process domains regarded as influential in barrier behaviour. Semi-diurnal, high-wate r tidal residuals from Halifax (Nova Scotia) tide gauge (1920-1990) ar e characterised for both surge magnitude and frequency on an annual ba sis. These two variables are combined to define three event types of a nnual surge histories. First-order, nth-step Markov analyses show that significant memory exists in 6-year and 22-year transitions between s urge event types. The longer transition sequence mirrors a major decad al mesoscale domain change in surge generation which is suggested to b e associated with phases of barrier crest reworking that enhance barri er retreat when the domain change occurs. The shorter transition seque nce may reflect cyclonic activity cycles on the Scotian Shelf superimp osed on the longer-term transition.