Variability of the Gulf Stream path observed from satellite infrared images

Tong Lee, University of Rhode Island

Abstract

Variability of the Gulf Stream path is studied using satellite infrared images for the period of April 1982 to December 1989. Issues addressed include propagation and growth of meanders, effects of the New England Seamounts on meanders, and temporal variation of meandering intensity and lateral oscillations of the entire stream.^ Progressive and retrogressive meanders co-exist at periods longer than several months; they are delimited in wavelength by stationary meanders. The empirical dispersion relation for the region of 74$\sp\circ$ to 70$\sp\circ$W is in good agreement with Inverted Echo Sounder measurements for short-period ($<$80 days) progressive meanders. The dispersion relation for a larger region, 75$\sp\circ$ to 60$\sp\circ$W, is different from that for 74$\sp\circ$ to 70$\sp\circ$W, primarily due to the downstream increase of meander amplitude and the corresponding decrease in phase speed, a consequence of the finite-amplitude effect. The $\beta$ effect is found to be important in controlling meander propagation. Topographic $\beta$ may play a more significant role than planetary $\beta$. It is argued that the presence of long-period standing meanders is a consequence of the combined effect of finite amplitude and $\beta$.^ The fastest-growing meanders have a period of 40 days and a wavelength of 350 km. The most-energetic meanders have a period of 46 days and a wavelength of 427 km. The spatial and temporal growth rates may be related by the group velocity.^ New England Seamounts do not have a significant effect on meanders having the most energetic period. However, the seamounts do affect meanders with periods shorter and longer than the most energetic period. It is argued that the mechanisms in which the seamounts affect short- and long-period meanders are different.^ Meandering intensity displays a dominant 9-month fluctuation which may excite transient Rossby waves near the Gulf Stream. Over 20% of the total space-time variance results from domain-wide lateral oscillations of the stream rather than from meandering. The domain-wide lateral oscillations have a strong seasonal cycle, with the stream being more northerly in the fall and southerly in the spring. The correlation between meandering intensity and domain-wide lateral oscillations is weak. ^

Subject Area

Physical Oceanography|Agriculture, Fisheries and Aquaculture|Remote Sensing

Recommended Citation

Tong Lee, "Variability of the Gulf Stream path observed from satellite infrared images" (1994). Dissertations and Master's Theses (Campus Access). Paper AAI9507078.
http://digitalcommons.uri.edu/dissertations/AAI9507078

Share

COinS