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Fast equatorial waves propagating at the top of the Earth's core
Author(s) -
Chulliat Arnaud,
Alken Patrick,
Maus Stefan
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl064067
Subject(s) - earth's magnetic field , geophysics , geology , inner core , core (optical fiber) , observatory , geodesy , geomagnetic secular variation , stratification (seeds) , outer core , rossby wave , physics , magnetic field , atmospheric sciences , geomagnetic storm , optics , astrophysics , seed dormancy , germination , botany , quantum mechanics , dormancy , biology
Since 2000, magnetic field variations originating in the core have been dominated by several pulses in the secular acceleration, leading to sharp geomagnetic “jerks” at the Earth's surface. Using models built from (i) Defense Meteorological Satellite Program data and (ii) Ørsted and Swarm satellites and ground observatory data, we show that a new pulse occurred in 2012.5, immediately following two pulses in 2006 and 2009. The three pulses can be decomposed into several equatorially symmetric modes propagating eastward and westward at 550 to 1100 km/yr, and one equatorially antisymmetric mode propagating eastward at 1650 km/yr. The characteristics of these modes are compatible to some extent with equatorial magnetic Rossby waves propagating within a 140 km thick layer at the top of the core with a density contrast of 50 ppm. This interpretation, if confirmed, would provide a new explanation for geomagnetic jerks and pulses based on stable stratification of the core.