Seasonal variations of sea surface height in the Gulf Stream region

Based on more than four years of altimetric sea surface height (SSH) data, the Gulf Stream shows distinct seasonal variations in surface transport and latitudinal position, with a seasonal range in the SSH difference across t he Gulf Stream of 0.14 m and a seasonal range in position of 0.42 degrees l at. The seasonal variations are most pronounced west (upstream) of about 63 degrees W, near the Gulf Stream's warm core. The changes in the SSH differ ence across the Gulf Stream are successfully modeled as a steric response t o ECMWF heat fluxes, after removing the large SSH variations due to seasona l position changes of the Gulf Stream. A phase shift between predicted and observed SSH changes in the Gulf Stream suggests that advection may be impo rtant in the seasonal heat budget. Consistent with the interpretation of SS H variations as steric, comparisons with hydrographic data suggest that the fail maximum SSH difference is from the upper 250 m of the water column. T he maximum volume transport is in the spring. Zonally averaged indices are used to quantify seasonal changes in the Gulf Stream, which are analogous t o changes in the atmospheric jet stream.