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

Lookup NU author(s): Professor Matt King, Dr Christopher Watson, Dr Nigel Penna, Professor Peter ClarkeORCiD

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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. Copyright 2008 by the American Geophysical Union.

Publication metadata

Author(s): King MA, Watson CS, Penna NT, Clarke PJ

Publication type: Article

Publication status: Published

Journal: Geophysical Research Letters

Year: 2008

Volume: 35

Issue: 3

ISSN (print): 0094-8276

ISSN (electronic): 1944-8007

Publisher: American Geophysical Union

URL: http://dx.doi.org/10.1029/2007GL032252

DOI: 10.1029/2007GL032252

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