Climate-ocean Variability and Sea Level In The Northwest Atlantic Region: A Sea-salinity-sea Level Linkage?
Abstract
Correlation of a 3000-yr-long record of small amplitude (cm-dm), low-frequency (10- 100yr) sea-level variations from a salt marsh in Connecticut, USA, with proxy record of past solar variability (14C) shows, for much of the record, a rather consistent phase shift of ca. 125 years. This result suggests that sea level in the Northwest Atlantic is linked to solar variations by a process with a comparable response time. Independently of this finding, a coupled General Circulation Model of intermediate complexity (EC- Bilt) was used to assess the impact of solar irradiance changes on steric sea-level variability. The model shows that northern North Atlantic steric sea level is strongly related to overturning, which, in turn, is strongly anti-correlated with irradiance. The mechanism is that irradiance changes create surface-temperature anomalies that influ- ence the rate of overturning. Variations in the overturning rate create surface salinity anomalies which, once advected to the deep ocean, results in steric sea-level change. In the model it takes some 100 years for the deep ocean salinity anomaly to arrive in the Gulf Stream region, where it continues to dominate multi-decadal/centennial North Atlantic sea level. Comparison of the modeled solar-forced steric sea level vari- ations in the Gulf Stream area for the past millenium with the corresponding part of the sea-level curve from Connecticut shows a satisfactory agreement. This result in- dicates that deep ocean salinity anomalies in the northern North Atlantic, induced by changes in irradiance, largely explains the timing of sea-level variations as recorded in the studied saltmarsh.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.3994V