Diurnal and Semi-Diurnal Earth Rotation Derived from 35 years of VLBI measurements.

Monday, 15 December 2014: 11:20 AM
John M Gipson, NASA Goddard Spaceflight CTR, Greenbelt, MD, United States; NVI, Inc./NASA Goddard Spaceflight Center, Greenbelt, MD, United States
I present an empirical model of diurnal and semi-diurnal Earth Rotation ('HF-EOP') derived from 35 years of VLBI data, and compare the results against other models derived from Space Geodesy (SG) using GPS and/or VLBI, as well as results derived from various satellite altimetry tidal models ('tidal models'). I discuss various alternative ways of estimating HF-EOP. Overall there is good agreement among the empirical SG HF-EOP models, as well as among the HF-EOP models derived from tidal models. The agreement between the empirical SG models and tidal models is not as good. Including the effect of libration improves the agreement, but there are still significant discrepancies. I also discuss some consequences of using the orthotide formalism as implemented in the 2010 IERS conventions, and suggest some ways to improve the IERS HF-EOP model.