Seasonal Changes in the North Atlantic Subtropical Gyre

• Published in: Journal of Geophysical Research
• Main Authors: Stramma, Lothar, Siedler, Gerold
• Format: Article in Journal/Newspaper
• Language: English
• Published: AGU (American Geophysical Union) 1988
• Subjects: North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/15384/; https://oceanrep.geomar.de/id/eprint/15384/1/JC093iC07p08111.pdf; https://doi.org/10.1029/JC093iC07p08111

The eastern part of the North Atlantic subtropical gyre is found in the region between the Azores and the Cape Verde Islands. A study of the gyre structure in the area east of 35°W between 8°N and 41°N is presented. The geostrophic flow field determined from historical temperature-salinity data sets by objective analysis indicates seasonal variations in shape but no significant changes in the magnitude of volume transports. The eastern part of the gyre has a larger east-west and smaller north-south extension in summer compared with the winter season. The center shifts by about 2° latitude to the south from winter to summer. Long-term temperature time series (6.5 years) from a mooring near the Azores are consistent with these results, showing always a consistent temperature increase at the beginning of the year which is apparently due to the displacement of the northeastern part of the gyre. A comparison between the mean flow fields and fields obtained from individual zonal sections indicates large deviations north and south of the gyre but small deviations within the gyre.