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Subdaily signals in GPS observations and their effect at semiannual and annual periods
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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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.
|Keywords:||GPS; sub-daily signals; geophysical loading|
|Journal or Publication Title:||Geophysical Research Letters|
|Page Range:||pp. 1-5|
|Identification Number - DOI:||10.1029/2007GL032252|
Copyright 2008 by the American Geophysical Union.
|Date Deposited:||25 Jul 2008 03:23|
|Last Modified:||18 Nov 2014 03:45|
|Item Statistics:||View statistics for this item|
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