Estimation of Short-Wavelength Gravity on a Dense Grid Using Digital Terrain Elevation Data

摘要

The precise determination of the gravity field at or near the earth's surface is required for compensating navigation/guidance systems and for testing gravity gradiometers. With conventional gravimeters it is usually impractical to measure the gravity field over an extended area at very short wavelengths(e.g., wavelengths less than 10 km). Since very short-wavelength gravitational perturbations at the surface are caused largely by near-surface mass variations in the local area, and since digital terrain elevation data(DTED)are available on dense grids(e.g. three arc second spacing)for selected regions, the very short-wavelength components of gravity can be estimated without a gravity survey by using the DTED and the assumption of constant mass density. This report presents an approach to computing the short-wavelength, terrain-induced gravity field at a prescribed rms accuracy. For a relatively flat test area in Oklahoma, the rms effect of terrain elevation on the gravity field at mean elevation for wavelengths shorter than 10 km varies between 0.6 mgal and 2.2 mgal. The largest point value of the high-frequency terrain effect is 18.0 mgal. (jhd)