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Subdaily signals in GPS observations and their effect at semiannual and annual periods

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King, MA and Watson, CS and Penna, NT and Clarke, PJ (2008) Subdaily signals in GPS observations and their effect at semiannual and annual periods. Geophysical Research Letters, 35 (L03302). pp. 1-5. ISSN 0094-8276

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Abstract

Estimates of seasonal geophysical loading from GPS may be biased by propagated unmodeled subdaily signals. Although the major geophysical signals at semidiurnal and diurnal frequencies are now routinely modeled in GPS analyses, the characteristics of unmodeled or mismodeled subdaily signals are not well known. Here, using site coordinates estimated every 5 minutes, we examine the subdaily coordinate spectral characteristics for ~90 global GPS sites. Unmodeled signals with amplitudes at the 10 mm level are present at frequencies between ~1/day and the Nyquist frequency. These are shown to propagate into 24 h solutions with (among other frequencies) annual and semiannual periods with amplitudes up to 5 mm, with a median amplitude in the height component of 0.8 mm (annual) and 0.6 mm (semiannual). They are shown to bias low-degree spherical harmonics estimates of geophysical loading at the level of 5–10%, although the exact effect will be network dependent.

Item Type: Article
Keywords: GPS; sub-daily signals; geophysical loading
Journal or Publication Title: Geophysical Research Letters
Page Range: pp. 1-5
ISSN: 0094-8276
Identification Number - DOI: 10.1029/2007GL032252
Additional Information: Copyright 2008 by the American Geophysical Union.
Date Deposited: 25 Jul 2008 03:23
Last Modified: 18 Nov 2014 03:45
URI: http://eprints.utas.edu.au/id/eprint/6993
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