| Summary: | A series of absolute gravity measurements have been made at National Geophysical Research Institute, Hyderabad and at Maitri, Indian Antarctic station to establish precise reference gravity stations and also to monitor long-term gravity changes for different geophysical studies. These precise measurements are made with an FG-5 absolute gravity meter, which measures the gravitational acceleration with an accuracy of 20 nm-s-2 (2 μGal). Non-tidal time series of measured absolute gravity values at these locations indicate systematic daily and seasonal variation of variable amplitudes. Daily changes are probably caused due to inaccurate global tidal model used in processing of data and suggest a need for better tidal model for the Indian sub-continent. Seasonal changes appear to be mainly caused due to hydrological effects, which can be modelled to derive the aquifer parameters.
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