Thursday 01 Nov 2012: Evidence for Lunar Tidal Signature in Records of Earth's Relative Paleointensity (Taylor and Francis sponsored)
Prof Kieth Aldridge - York University, Canada
Harrison 101 14:00-15:00
A search of composite stacks of relative paleointensity SINT2000 and
PISO-1500 for coherence with a simulated lunar tidal strain over the past 2
Myr shows significant coherence at periods ranging over 12,500 to 3500 years.
Tidal strains were estimated from a non-dissipative simulation of lunar range.
Our search for coherence between lunar strain and relative paleointensity is
based on a representation of long term fluctuations in geomagnetic intensity
as a sequence of growths and decays, which are due to a tidally-induced
parametric instability in Earth's fluid core. An important consequence of
this depiction is the precise temporal location of 6 reversal events over the
past 2 Myr. A parametric instability in Earth's core is consistent with both
the success in predicting reversals and the coherence between relative paleointensity
and lunar tidal strain. Indeed the periods found for coherence are
geophysically plausible for the growth of parametric instability in Earth's
core. Accordingly we conclude that these results are consistent with a
parametric instability participating in the geodynamo.