Spatio-temporal characteristics of secular acceleration pulses at the core surface
Abstract
In a recent study (Chulliat et al., 2010), we identified a core field acceleration pulse reaching its maximum power around 2006 at the core surface, and having its maxima under the Equatorial Atlantic Ocean and the Eastern Indian Ocean. Geomagnetic jerks were found in observatory data before (around 2003) and after (around 2007) this pulse. Here we extend this analysis to the time intervals covered by the CHAOS-4, CM4 and gufm1 models. Despite limitations in recovering the field acceleration from time-dependent core field models, we find another pulse in 2009, immediately following the 2007 jerk, and another one near 1972, between the 1969 and 1978 jerks. Other less prominent pulses are found, particularly near 1968 and 1982. We will present results of a spatio-temporal analysis of these events, as well as an assessment of their robustness based upon a direct modeling of the field acceleration at the core surface. Possible physical mechanisms leading to the formation of acceleration pulses will also be discussed.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMGP31A1088C
- Keywords:
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- 1507 GEOMAGNETISM AND PALEOMAGNETISM / Core processes;
- 1541 GEOMAGNETISM AND PALEOMAGNETISM / Satellite magnetics: main field;
- crustal field;
- external field;
- 1555 GEOMAGNETISM AND PALEOMAGNETISM / Time variations: diurnal to decadal