Improved GPS time series in Southern California through the combination of SOPAC and JPL solutions

The Southern California Integrated GPS Network (SCIGN) is now in full operation and provides valuable information on deformation due to tectonic, geomorphic and hydrologic processes. We combine the daily loosely constrained solutions from SOPAC and JPL analysis centers to derive integrated time series to enhance the signal to noise ratio and to provide versatile services to tectonic researchers. We investigate the process model and strategy of the two analyses centers first and try to correct the systematic differences between the solutions of the two centers before the formal combination. Our combination methodology, the definition of the reference frame, the quality control and the final products will be addressed. Our preliminary times series analyses reveals secular tectonic movement, seasonal mass loading caused deformation, and some short term transient variations. In particular, the vertical components of the site position time series also provide useful constraints on tectonic movement and other geophysical processes.