Nontidal Oceanic Effects on Temporal Variations in the Earth's Gravitational Field

Based on the global numerical ocean models,the contributions of nontidal oceanic mass change to the seasonal variations in the low-degree Earth's gravitational field are estimated.The combined effects of the atmosphere,surface water and ocean on the gravitational field predicted by the models are used to compare the values determined by satellite laser ranging(SLR) observations.The results show that the effect of mass conservation correction due to volume conservation approximation used in the numerical ocean models on ΔJ₂ is obvious on the seasonal timescales,but negligible for ΔJ₃.The annual and semiannual amplitudes of the SLR-determined ΔJ₂ are in between the combined values of ocean,surface water and atmosphere with(IB) and(NIB).