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Subdaily signals in GPS observations and their effect at semiannual and annual periods
journal contribution
posted on 2023-05-16, 22:47 authored by Matt KingMatt King, Christopher WatsonChristopher Watson, Penna, NT, Clarke, PJEstimates 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.
History
Publication title
Geophysical Research LettersVolume
35Article number
L03302Number
L03302Pagination
1-5ISSN
0094-8276Department/School
School of Geography, Planning and Spatial SciencesPublisher
American Geophysical UnionPlace of publication
United States of AmericaRepository Status
- Restricted