Abstract

The drift characteristics specific to an unstable gravimeter has been modeled to enhance high quality data that will be useful for gravimetric studies and to determine proper timing of field observations. A pre-field observation was carried out to monitor the tide and thus limiting the relative gravity observation to near-linear time window. Closed loop sequence technique of re-occupying a drift base compatible with the drift characteristics of the Lacoste and Romberg (model G446) and cascade model for the computation of drift were combined to obtain a more reliable data that fulfills the linear drift assumption. Subjecting the modelled drift to descriptive statistics a maximum value (1.6550mGal) and minimum value (- 0.3720mGal) of drift were obtained. This variability in drift values and the disparity between the mean (0.099mGal) and the standard deviation (0.2914mGal) is a pointer to various factors that caused the instrumental drift. Such factors could be attributed to external temperature, age and usage of the gravimeter, mechanical stress and strain in the mechanism as the gravimeter is moved and subjected to vibrations. The low standard error of the mean (0.0196mGal) is a reflection of the validity of the linear drift assumption using the cascade model and the field procedure compatible with the drift characteristics of the gravimeter.

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