Measurement of gravity at sea and in the air

Abstract

General problems of gravity measurement at sea are discussed. A treatment of the effects of vertical accelerations shows that gravity meter nonlinearities cause errors that ordinarily are proportional to the square of the vertical acceleration. In a treatment of horizontal accelerations, similarities and differences that exist between gimbal supported and stabilized platform gravity meters are pointed out. It is shown that optimization of the parameters of a stabilized reference can reduce gravity meter errors by two or more orders of magnitude at long periods. A method for correcting for inadequate period of a stabilized reference is given. The Schuler‐tuned stabilized platform is briefly described. The theory of inherent type cross coupling and examples of imperfection type cross coupling are given. Theory and significant details of construction are given for the LaCoste and Romberg (L&R) gravity meter and stabilized platform. Tests on L&R air‐Sea gravity meters made during the last decade are discussed. The largest error in earlier work is shown to have been due to vertical accelerations. A method of correcting for these errors is described. Tests indicate that presently attainable accuracy of L&R gravity meters is appreciably better than 1 mgal.