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Tidal gravity variations revisited at Vostok Station, Antarctica

Citation

Doi, K and Shibuya, K and Wendt, A and Dietrich, R and King, MA, Tidal gravity variations revisited at Vostok Station, Antarctica, Polar Science, 3, (1) pp. 1-12. ISSN 1873-9652 (2009) [Refereed Article]

DOI: doi:10.1016/j.polar.2008.11.001

Abstract

In 1969, prior to the discovery of the subglacial Lake Vostok, an Askania Gs-11 gravimeter was operated at Vostok Station (78.466°S, 106.832°E; 3478 m asl) to observe tidal gravity variations. To gain a better understanding of the lake's tidal dynamics, we reanalyzed these data using a Bayesian Tidal Analysis Program Grouping method (BAYTAP-G and -L programs). The obtained phase leads for the semidiurnal waves M2 (6.6 ± 2.1°) and S2 (10.1 ± 4.2°) are more pronounced than those of the diurnal waves, among which the largest phase lead (for K1) was 5.0 ± 0.5°. The obtained δ factor for M2 was 0.890 ± 0.032, significantly less than the theoretical value of 1.16. For three global ocean tide models (NAO99b, FES2004, and TPXO6.2), the estimated load tides on waves Q1, O1, P1, K1, M2, and S2 range from 0.1-0.2 μGal (Q1 and S2) to 0.6-0.7 μGal (K1). The difference in amplitude among the three models is less than 0.14 μGal (M2), and the difference in phase is generally less than 10°. In calculating the residual tide vectors using the ocean models, the TPXO6.2 model generally gave the smallest residual amplitudes. Our result for the K1 wave was anomalously large (1.36 ± 0.25 μGal), while that for the M2 wave was sufficiently small (0.37 ± 0.17 μGal). The associated uncertainty is half that reported in previous studies. It is interesting that the residual K1 tide is approximately 90° phase-leaded, while the M2 tide is approximately 180° phase-leaded (delayed). Importantly, a similar reanalysis of data collected at Asuka Station (71.5°S, 24.1°E) gave residual tides within 0.2-0.3 μGal for all major diurnal and semidiurnal waves, including the K1 wave. Therefore, the anomalous K1 residual tide observed at Vostok Station must be linked to the existence of the subglacial lake and the nature of solid-ice-water dynamics in the region. © 2009 Elsevier B.V. and NIPR.

Item Details

Item Type:Refereed Article
Keywords:Askania Gs-11 gravimeter; Ocean load tides; Subglacial Lake Vostok; Tidal gravity change; Bayesian analysis; gravimetry; gravity field; semidiurnal tide; subglacial environment; tidal modeling; Antarctica; East Antarctica; Vostok Station
Research Division:Earth Sciences
Research Group:Physical Geography and Environmental Geoscience
Research Field:Physical Geography and Environmental Geoscience not elsewhere classified
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:King, MA (Professor Matt King)
ID Code:81992
Year Published:2009
Web of Science® Times Cited:2
Deposited By:Geography and Environmental Studies
Deposited On:2013-01-14
Last Modified:2013-01-14
Downloads:0

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