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Impacts of the cryosphere and atmosphere on observed microseisms generated in the Southern Ocean


Turner, RJ and Gal, M and Hemer, MA and Reading, AM, Impacts of the cryosphere and atmosphere on observed microseisms generated in the Southern Ocean, Journal of Geophysical Research: Earth Surface, 125, (2) Article e2019JF005354. ISSN 2169-9003 (2020) [Refereed Article]


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Copyright 2020 American Geophysical Union

DOI: doi:10.1029/2019JF005354


The Southern Ocean (in the region 60-180 E) south of the Indian Ocean, Australia, and the West Pacific is noted for the frequent occurrence and severity of its storms. These storms give rise to high-amplitude secondary microseisms from sources, including the deep ocean regions, and primary microseisms where the swells impinge on submarine topographic features. A better understanding of the varying microseism wavefield enables improvements to seismic imaging and development of proxy observables to complement sparse in situ wave observations and hindcast models of the global ocean wave climate. We analyze 12-26 years of seismic data from 11 seismic stations either on the East Antarctic coast or sited in the Indian Ocean, Australia, and New Zealand. The power spectral density of the seismic wavefield is calculated to explore how the time-changing microseism intensity varies with (i) sea ice coverage surrounding Antarctica and (ii) the Southern Annular Mode (SAM) climate index. Variations in sea ice extent are found to be the dominant control on the microseism intensity at Antarctic stations, which exhibit a seasonal pattern phase-shifted by 4-5 months compared to stations in other continents. Peaks in extremal intensity at East Antarctic stations occur in March-April, with the highest peaks for secondary microseisms occurring during negative SAM events. This relationship between microseism intensity and the SAM index is opposite to that observed on the Antarctic Peninsula. This work informs the complexity of microseism amplitudes in the Southern Hemisphere and assists ongoing interdisciplinary investigations of interannual variability and long-term trends.

Item Details

Item Type:Refereed Article
Keywords:microseisms, southern ocean, sea ice, southern annular mode (SAM)
Research Division:Earth Sciences
Research Group:Geophysics
Research Field:Seismology and seismic exploration
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the environmental sciences
UTAS Author:Turner, RJ (Dr Ross Turner)
UTAS Author:Gal, M (Mr Martin Gal)
UTAS Author:Reading, AM (Professor Anya Reading)
ID Code:139131
Year Published:2020
Funding Support:Australian Research Council (DP150101005)
Web of Science® Times Cited:1
Deposited By:Physics
Deposited On:2020-05-27
Last Modified:2020-06-17
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