For G05: 


Reference frame induced noise in CGPS coordinate time series.

Kierulf, H. P. and Plag, H.-P. 

Global scale studies of changes in the Earth's geometry due to
geodynamics and surface loading, including problems related 
to global change (such as sea level changes) require access to a highly accurate
global reference frame with spatially homogeneous accuracy. Today, such access 
is only available through GPS, which allows to determine point coordinates
relative to the International Terrestrial Reference Frame (ITRF). 
The International GPS Service (IGS) provides global products 
(satellite orbits and clocks, SOC) as well as time series of the 
reference coordinates for the IGS tracking stations that can be used to 
determine coordinates of new points either through single point positioning relative
to the SOC or by using additional information from nearby reference sites.
We will study the quality of the IGS products in terms of long-term stability
and accuracy relative to ITRF and discuss potential noise introduced by these products 
into coordinate time series determined from Continuous GPS (CGPS) observations.
Through comprison to homogeneous SOC provided by the Jet Propulsion 
Laboratory (JPL), we will assess the noise due to IGS products and also 
quantify the noise introduced by inconsistencies between the processing used 
to generate the global products and the single point positioning processing.