THE EFFECT OF COASTLINE CURVATURE ON THE WEAKENING OF ATLANTIC TROPICAL CYCLONES

This study attempts to determine the relationship between the curvatur e of the coastline and the filling (increase n centra pressure) of hur ricanes and tropical storms by comparing both the rate of filling and the total filling for storms striking convex, concave, and linear coas tlines. The USA and Mexican coastline was approximated by a subjective smoothing procedure, and the coastal curvature corresponding to each landfalling Atlantic tropical cyclone from 1900 to 1979 was measured a nd grouped into one of the three curvature categories. Storm-filling r ates and total amounts of filling were determined before and after lan dfall by computing the change in wind speed for various Saffir-Simpson hurricane intensity categories. The averages of these variables withi n each strength and curvature grouping were compared in order to deter mine if they were statistically different. Storms were also compared i n order to determine if stronger storms fill a greater total amount th an weaker storms, regardless of the coastline's curvature. Concave coa sts were found to be associated with storms filling both more rapidly and by a greater amount than convex coasts for weak hurricanes and str ong tropical storms, and they were associated with storms that filled by a greater amount for hurricanes of moderate strength. This most lik ely results from the lower water-to-land ratios associated with storms striking concave coasts and the reduction in latent and sensible heat fluxes from the surface. Also, stronger storms were found to fill mor e rapidly and by a greater total amount than weaker storms, and storms striking the East Coast generally filled more rapidly and by a greate r total amount than storms striking the Gulf Coast or Florida.