Interannual coherence between North Atlantic atmospheric surface pressure and composite southern U.S.A. sea level

Abstract

Annual mean sea levels along the southern United States have been examined for interannual variability. Fifteen sea level stations from Cape Hatteras to the Rio Grande that best covered the three lunar nodal cycles from 1931–1987 were selected for analysis. Linear trends, ranging from +0.2 cm/yr to +1.4 cm/yr were subtracted from their respective series, leaving remarkably similar residuals. The composite time series of the 15 residuals was compared with time series of surface air pressure over the North Atlantic Ocean during the period 1947–1987. The best correlation is a negative relationship between composite sea level and wintertime air pressure north of 45°N, and a positive relationship from 20°–45°N. The most significant correlations (−0.73 and +0.51) were found for 60°N, 20°W and for 30°N, 25°W respectively. Wintertime meridional air pressure gradient between these two latitudes represents about 50% of the variance in composite annual mean sea level. Both the sea level and air pressure time series had significant spectral peaks at 13.3 and 4.4 years, with about 52% of the covariance coming from these two periods.