Coastal Water Level Measurements, Northeast Gulf of Mexico

Abstract

Eight months (April-November) of National Ocean Survey water level data from an unprotected open coast site (Gulf Shores, AL) and a protected coastal embayment site (Dauphin Island, AL), have been compared with each other and with the local winds (Dauphin Island, AL). The subtidal records have similar shape and show no statistical difference in sample variance or spectrum levels between sites. Although not statistically different, the subtidal spectrum levels are higher in the fall and spring and lower in the summer at the protected site. Cross-spectral analysis between the subtidal records and the wind stress components indicate similar response at both sites, In general, subtidal water level records are coherent over broader frequency bands with the alongshore wind stress than with the across-shore wind stress. The protected site water level is coherent with alongshore wind stress at higher subtidal frequencies in the spring and fall and lower subtidal frequencies in the summer, than the open coast water level. Neither water level is coherent with the across-shore wind stress in the spring or summer and only in a narrow band in the fall.