Abstract:

Several independent time series of variations J2 in Earth’s gravity field are compared from GRACE, geophysical model and satellite laser ranging (SLR) for the period April 2002 to October 2010. We compute the atmospheric induced J2 variations for both inverted (IB) and non-inverted-barometer (NIB) response of the oceans. The results of the comparison show that the annual term amplitude of J2 in NIB case is bigger by a 3 factor than that in IB case, the difference of the both phase is 47°; At the annual frequency, atmospheric pressure and surface ground water effects are the dominate contributors; For the semi-annual term, the amplitudes and phases of the atmospheric pressure, ocean and surface ground water do not agree very well, especially for the results of the atmospheric pressure in IB case; GRACE, geophysical model and SLR annual J2 estimates agree well. The amplitude from GRACE is bigger about 50 percent. The annual amplitude from SLR is between that from the geophysical model in IB case and in NIB case. The semi-annual amplitude estimated from GRACE and SLR is the same. The difference of the semi-annual variations between geophysical model (IB) and SLR is the biggest.

Key words: geophysical model, SLR, GRACE, gravity