Paleointensity Estimates from the Pleistocene of Northern Israel:
Implications for hemispheric asymmetry in the time averaged field
Abstract
Twenty-two sites, subjected to an IZZI-modified Thellier-Thellier
experiment and strict selection criteria, recover a paleomagnetic axial
dipole moment (PADM) of 62.2$\pm$ 30.6 ZAm$^2$ in
Northern Israel over the Pleistocene (0.012 - 2.58 Ma). Pleistocene data
from comparable studies from Antarctica, Iceland, and Hawaii,
re-analyzed %\cite{cromwell15b,asefaw21}
using the same criteria and age range, show that the Northern Israeli
data are on average slightly higher than those from Iceland (PADM = 53.8
$\pm$ 23 ZAm$^2$, n = 51 sites) and even higher
than the Antarctica average %\cite{asefaw21}
(PADM = 40.3 $\pm$ 17.3 ZAm$^2$, n = 42 sites).
Also, the data from HSDP2 spanning the last half million years (PADM =
76.7 $\pm$ 21.3 ZAm$^2$, n = 59 sites) are higher
than those from Northern Israel. These results, when compared to
Pleistocene results filtered from the PINT database (www.pintdb.org)
suggest that data from the Northern hemisphere mid-latitudes are on
average higher than those from the southern hemisphere and those from
latitudes higher than 60$^{\circ}$N.
The weaker intensities found at high (northern and southern) latitudes
therefore, cannot be attributed to inadequate spatio-temporal sampling
of a time-varying dipole moment or low quality data. The high fields in
mid-latitude Northern hemisphere could result from long-lived non-axial
dipole terms in the geomagnetic field with episodes of high field
intensities occurring at different times in different longitudes. This
hypothesis is supported by an asymmetry predicted from the Holocene, 100
kyr, and five million year time averaged geomagnetic field models.