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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:07 |
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Conference: Bucharest University Faculty of Physics 2006 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Conceptual and physical mechanisms
for Dansgaard-Oeschger and Heinrich events
Authors:
Mihai Dima(1)(2), Gerrit Lohmann(2)
Affiliation:
(1)University of Bucharest, Faculty of Physics, Dept. of Atmospheric Physics, P.O.BOX MG-11, Bucharest
(2) Alfred Wegener Institute for Polar and Marine Research, Bremen, Germany
E-mail
mdima@rdslink.ro
Keywords:
abrupt climate change, solar forcing, termohaline circulation
Abstract:
Dansgaard-Oeschger and Heinrich events are probably the most pronounced climate changes over the last 120 000 years. Although many of their properties were derived from climate reconstructions, the associated physical mechanisms are not yet fully understood. They are paced by a cycle with a ~1500 years period whose origin remains unclear. We show that this millennial mode results from the rectification of the solar forcing, through threshold response of the thermohaline circulation. It is argued that the ~1500 years cycle is a derived mode of no specific physical relevance, in the sense that there are no physical processes with this characteristic timescale. The cycle results from the linear representation in the Fourier space of nonlinearly transformed fundamental modes, of solar origin.
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