Reference : Nontidal ocean loading: amplitudes and potential effects in GPS height time series
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
Nontidal ocean loading: amplitudes and potential effects in GPS height time series
van Dam, Tonie mailto [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Engineering Research Unit >]
Collilieux, X. [> >]
Wuite, J. [> >]
Altamimi, Z. [> >]
Ray, J. [> >]
Journal of Geodesy
Yes (verified by ORBilu)
[en] Loading effects pressure Height coordinate time series; Annual signals ; Ocean bottom pressure ; Annual signals
[en] Ocean bottom pressure (OBP) changes are caused
by a redistribution of the ocean’s internal mass that are driven
by atmospheric circulation, a change in the mass entering or
leaving the ocean, and/or a change in the integrated atmospheric
mass over the ocean areas. The only previous global
analysis investigating the magnitude of OBP surface displacements
used older OBP data sets (van Dam et al. in
J Geophys Res 129:507–517, 1997). Since then significant
improvements in meteorological forcing models used to predict
OBP have been made, augmented by observations from
satellite altimetry and expendable bathythermograph profiles.
Using more recent OBP estimates from the Estimating
the Circulation and Climate of the Ocean (ECCO) project,
we reassess the amplitude of the predicted effect of OBP on
the height coordinate time series from a global distribution
of GPS stations. OBP-predicted loading effects display an
RMS scatter in the height of between 0.2 and 3.7 mm, larger
than previously reported but still much smaller (by a factor
of 2) than the scatter observed due to atmospheric pressure
loading. Given the improvement in GPS hardware and data
analysis techniques, the OBP signal is similar to the precision
of weekly GPS height coordinates. We estimate the effect of OBP on GPS height coordinate time series using
the MIT reprocessed solution, mi1. When we compare the
predicted OBP height time series with mi1, we find that the
scatter is reduced over all stations by 0.1 mm on average
with reductions as high as 0.7 mm at some stations. More
importantly we are able to reduce the scatter on 65 % of
the stations investigated. The annual component of the OBP
signal is responsible for 80 % of the reduction in scatter on
average.We find that stations located close to semi-enclosed
bays or seas are affected by OBP loading to a greater extent
than other stations.

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