Earths variable rotation is mainly produced by the variability of the AAM(atmospheric angular momentum). In particular, the axial AAM component X_3, which undergoes especially strong variations,induce
Based on the observations of 36 gPhone gravimeters in 2015, the background noise levels in the seismic frequency band(200-600 s) and sub-seismic band(1-6 h) are calculated. The differences in the PSD(