POSSIBLE EFFECTS OF SOLAR-INDUCED AND INTERNAL CLIMATE VARIABILITY ON THE THERMOHALINE CIRCULATION

Due to its nonlinear dynamics and involvement in abrupt climate changes, the thermohaline circulation is a key component of the climate system. Numerical studies have shown that it is sensitive to the sea-ice export from the Arctic in the North Atlantic, through Fram Strait. Here we applied the Singular Spectrum Analysis method to identify quasi-periodic modes/components in a reconstruction of Fram Strait Sea Ice Export for the 1820-2000 periods. Several decadal and multidecadal modes are identified. Based on composite sea surface temperature and sea level pressure maps it is argued that a decadal and multidecadal mode are associated to solar forcing, while another decadal mode is of internal origin. The results may be useful in identifying the mechanisms of solar influence on the thermohaline circulation and have implications for the understanding of past climate changes.