INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Seasonal effects in the weekly realization of the SIRGAS reference frame
C. BRUNINI; H. DREWES; L. SÁNCHEZ,; V. MACKERN,; L. MATEO
Congreso; EGU General Assembly 2010.; 2010
European Geosciences Union
Usually, epoch solutions (daily, weekly, multi-year) of regional reference networks are aligned to the global reference frame (ITRF) using a set of fiducial stations with known positions and constant velocities. However, GNSS stations show significant seasonal position variations (mainly in the up component) resulting from a combination of geophysical loading and systematic errors. Ignoring these seasonal variations at reference stations can cause systematic errors in the datum realization, and the reference networks can significantly be deformed. These effects are larger in regional networks than in global ones, especially in zones with strong seasonal variations like the SIRGAS region (Fig. 1). To evaluate the impact of seasonal variations in the weekly realization of the SIRGAS frame, free normal equations are solved applying two different sets of reference coordinates for the datum realization: the first set corresponds to the IGS05 positions at epoch 2000.0 extrapolated to the observation epoch using the ITRF2005 velocities (IGS05@2000 + VEL). The second set corresponds to the weekly positions determined for the IGS05 reference stations within the IGS weekly combination (igsyyPwwww.snx).