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A new global mode of Earth deformation: Seasonal cycle detected

Lookup NU author(s): Professor Geoffrey Blewitt, Dr David Lavallee, Professor Peter ClarkeORCiD


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We have detected a global mode of Earth deformation that is predicted by theory. Precise positioning of Global Positioning System sites distributed worldwide reveals that during February to March, the Northern Hemisphere compresses (and the Southern Hemisphere expands), such that sites near the North Pole move downward by 3.0 millimeters, and sites near the equator are putted northward by 1.5 millimeters. The opposite pattern of deformation occurs during 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 6.9 x 10(22) kilogram meters near the North Pole in winter, indicating interhemispheric mass exchange of 1.0 x 10(16) +/- 0.2 x 10(16) kilograms.

Publication metadata

Author(s): Blewitt G, Lavallée DA, Clarke PJ, Nurutdinov K

Publication type: Article

Publication status: Published

Journal: Science

Year: 2001

Volume: 294

Issue: 5550

Pages: 2342-2345

ISSN (print): 0036-8075

ISSN (electronic): 1095-9203

Publisher: American Association for the Advancement of Science


DOI: 10.1126/science.1065328


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