• Barnett, T. P., 1984: The estimation of “global” sea level change: A problem of uniqueness. J. Geophys. Res.,89 (C5), 7980–7988.

  • Bloomfield, P., 1976: Fourier Analysis of Time Series: An Introduction. Wiley, 258 pp.

  • Chelton, D. B., and M. G. Schlax, 1996: Global observations of oceanic Rossby waves. Science,272, 234–238.

  • Douglas, B. C., 1992: Global sea level acceleration. J. Geophys. Res.,97 (C8), 12 699–12 706.

  • Hicks, S. D., and J. E. Crosby, 1974: Trends and variability of yearly mean sea level 1893–1972. U.S. Dept. Commerce, NOAA, National Ocean Service, 14 pp. [Available from National Ocean Service/NOAA, 1315 East–West Highway, Silver Spring, MD 20910.].

  • Jin, F., 1997: A theory of interdecadal climate variability of the North Pacific ocean–atmosphere system. J. Phys. Oceanogr.,27, 1821–1835.

  • Joyce, T. M., and P. Robbins, 1996: The long-term hydrographic record at Bermuda. J. Climate,9, 3121–3131.

  • Kessler, W. S., 1990: Observations of long Rossby waves in the northern tropical Pacific. J. Geophys. Res.,95 (C4), 5183–5217.

  • Leaman, K. D., E. Johns, and T. Rossby, 1989: The average distribution of volume transport and potential vorticity with temperature at three sections across the Gulf Stream. J. Phys. Oceanogr.,19, 36–51.

  • Lozier, M. S., W. B. Owens, and R. G. Curry, 1995: The climatology of the North Atlantic. Progress in Oceanography, Vol. 36, Pergamon, 1–44.

  • Qiu, B., W. Miar, and P. Müller, 1997: Propagation and decay of forced and free baroclinic Rossby waves in off-equatorial oceans. J. Phys. Oceanogr.,27, 2405–2417.

  • Richardson, W. S., W. J. Schmitz Jr., and P. P. Niiler, 1969: The velocity structure of the Florida Current from the Straits of Florida to Cape Fear. Deep-Sea Res.,16 (Suppl.), 225–231.

  • Slutz, R. J., S. D. Woodruff, R. L. Jenne, and P. M. Steurer, 1987: A Comprehensive Ocean–Atmosphere Data Set. Bull. Amer. Meteor. Soc.,68, 1239–1250.

  • Sturges, W., and B. G. Hong, 1995: Wind forcing of the Atlantic thermocline along 32°N at low frequencies. J. Phys. Oceanogr.,25, 1706–1715.

  • ——, ——, and A. J. Clarke, 1998: Decadal wind forcing of the North Atlantic subtropical gyre. J. Phys. Oceanogr.,28, 659–668.

  • Woodworth, P. L., 1990: A search for accelerations in records of European mean sea level. Int. J. Climatol.,10, 129–143.

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Sea Level on the U.S. East Coast: Decadal Variability Caused by Open Ocean Wind-Curl Forcing

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  • 1 Department of Oceanography, The Florida State University, Tallahassee, Florida
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Abstract

One of the puzzling features of sea level on the east coast of the United States is the decedal-scale variability;the fluctuations are 10–15 cm, peak to peak, at periods longer than a few years. The authors find that this variability, in the frequency band treated with the model, is largely caused by a deep-sea signal generated by the wind stress curl over the North Atlantic. A simple forced long Rossby wave model of the response of the thermocline to wind forcing is used, computing long-wave speeds from observed hydrographic data. The authors model the response of the ocean at periods longer than 3 years for the full width of the Atlantic and for the north–south extent of the main anticyclonic gyre, 18°–38°N. The model output in deep water shows remarkably good agreement with tide gauges, both at Bermuda (32°N) and Puerto Rico (18°N), as well as with dynamic height fluctuations of ∼20 cm peak to peak.

Once these fluctuations reach the western side of the ocean, the authors estimate coastal sea level by constructing a complementary coastal model. The coastal model is geostrophic and conserves mass within a nearshore region that encompasses the Gulf Stream. By extending this nearshore region as far south as 14°–18°N and using only the oceanic fluctuations to force the variability in the stream, between 80% and 90% of the variance of sea level at coastal tide gauges can be explained. Sea level along the coast is used to test the model assumptions. The basic results, however, seem important because they are constrained only by open ocean wind forcing and not by input boundary conditions.

Corresponding author address: Dr. B. G. Hong, Department of Oceanography, The Florida State University, Tallahassee, FL 32306-4320.

Email: bg@ocean.fsu.edu

Abstract

One of the puzzling features of sea level on the east coast of the United States is the decedal-scale variability;the fluctuations are 10–15 cm, peak to peak, at periods longer than a few years. The authors find that this variability, in the frequency band treated with the model, is largely caused by a deep-sea signal generated by the wind stress curl over the North Atlantic. A simple forced long Rossby wave model of the response of the thermocline to wind forcing is used, computing long-wave speeds from observed hydrographic data. The authors model the response of the ocean at periods longer than 3 years for the full width of the Atlantic and for the north–south extent of the main anticyclonic gyre, 18°–38°N. The model output in deep water shows remarkably good agreement with tide gauges, both at Bermuda (32°N) and Puerto Rico (18°N), as well as with dynamic height fluctuations of ∼20 cm peak to peak.

Once these fluctuations reach the western side of the ocean, the authors estimate coastal sea level by constructing a complementary coastal model. The coastal model is geostrophic and conserves mass within a nearshore region that encompasses the Gulf Stream. By extending this nearshore region as far south as 14°–18°N and using only the oceanic fluctuations to force the variability in the stream, between 80% and 90% of the variance of sea level at coastal tide gauges can be explained. Sea level along the coast is used to test the model assumptions. The basic results, however, seem important because they are constrained only by open ocean wind forcing and not by input boundary conditions.

Corresponding author address: Dr. B. G. Hong, Department of Oceanography, The Florida State University, Tallahassee, FL 32306-4320.

Email: bg@ocean.fsu.edu

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