Altimetry-derived Gulf Stream Property Changes: Is the Sea Level Rise Along the U.S. Eastcoast Linked to the Gulf Stream Slow Down?

The Gulf Stream (GS) properties estimated from altimetric sea surface height (SSH) measurements since late 1992 are analyzed in the region 80W to 50W, and compared with these from XBT and current meter measurements along a high-density XBT transect and Oleander section. During the altimeter period, GS experiences a strong southward shift, which is dominated by the region east of 65W after the GS passes the New England Seamount. This southward shift is accompanied by a weakening of the GS, which is largely attributed to the SSH increase to the north of the GS. However, to the west of 70W, no statistically significant weakening or southward shift was found. This is consistent with the measurements from the oleander section (crossing the Gulf Stream around 70.5W), which did not detect any significant trends in the GS transport. Also different from east of 65W where the SSH north of the GS has relatively large control of the cross-front SSH difference, west of 70W the changes of the SSH south of the GS dominates the SSH difference across the GS. Therefore, our results suggest that the sea level rise along the U.S. eastcoast is not directly linked to the GS slow down. However, it is possible that the heat transport convergence by the GS system causes the sea level rise, which is consistent with the increasing trends in the SST and air-sea heat flux into the atmosphere.