A new global mode of Earth deformation: seasonal cycle detected

We have detected a global mode of Earth deformation that is predicted by theory. Precise positioning of GPS sites distributed worldwide reveals that in February to March the northern hemisphere compresses (and the southern hemisphere expands), such that sites near the North Pole move downward by 3.0...

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Bibliographic Details
Main Authors: Blewitt, Geoffrey, Lavallee, David, Clarke, Peter, Nurutdinov, Konstantin
Format: Report
Language:unknown
Published: EarthArXiv 2017
Subjects:
Earth Sciences
Hydrology
Other Earth Sciences
FOS Earth and related environmental sciences
Other Oceanography and Atmospheric Sciences and Meteorology
Other Environmental Sciences
Geophysics and Seismology
Environmental Monitoring
Environmental Sciences
Physical Sciences and Mathematics
Oceanography and Atmospheric Sciences and Meteorology
Other Physical Sciences and Mathematics
North Pole
Online Access:https://dx.doi.org/10.17605/osf.io/yjeqv
https://eartharxiv.org/yjeqv/
Description
Summary:We have detected a global mode of Earth deformation that is predicted by theory. Precise positioning of GPS sites distributed worldwide reveals that in February to March the northern hemisphere compresses (and the southern hemisphere expands), such that sites near the North Pole move downward by 3.0 mm, and sites near the equator are pulled northwards by 1.5 mm. The opposite pattern of deformation occurs in August to September. We identify this pattern as the degree-one spherical harmonic response of an elastic Earth to increased winter loading of soil moisture, snow cover, and atmosphere. Data inversion shows the load moment’s trajectory as a great circle traversing the continents, peaking at 6.9e22 kg m near the North Pole in winter, indicating inter-hemispheric mass exchange of 1.0±0.2e16 kg.

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