Computation demo for the terrain effect and gravity prospecting model

Demonstrates the fundamental workflow for computing unified land-sea complete Bouguer effects on gravities. Utilizing a Digital Elevation Model (DEM) and discrete gravity disturbances in near-Earth space derived from the EGM2008 geopotential model, the process employs a Remove-Restore scheme centered on Residual Terrain Effects (RTE). The target output is a grid of complete Bouguer gravity disturbances on a terrain equielevation surface, which simultaneously serves as the observation reduction surface.

Demonstrates a rapid workflow for computing classical Bouguer gravity anomalies (or disturbances) and isostatic gravity anomalies (or disturbances) for any global region. Utilizing an Earth geopotential coefficient model and a land-sea terrain mass spherical harmonic coefficient model, the process executes four key steps to synchronously generate unified land-sea anomaly models.

[Physical Definition] The Complete Bouguer Effect is defined as the variation in the Earth's gravity field resulting from:

(1) The removal of topographic masses above the geoid.

(2) The compensation of seawater density to the land topographic density.

PAGravf4.5 empowers users with high-precision analytical computation of diverse terrain effects on various gravity field elements on and outside the geoid. Concurrently, it features full-space, all-element gravity field analytical modeling capabilities that integrate multi-source, heterogeneous, varying-altitude, cross-distributed, and multi-type data encompassing terrestrial, maritime, aerial, and space-based observations. The synergy of these capabilities effectively resolves the analytical modeling challenges of geophysical gravity exploration under complex observational scenarios.

(1) Application Scenario

In any region globally, PAGravf4.5 can integrate multi-source heterogeneous data –including gravity, gravity gradients, (astronomical) vertical deflections, satellite altimetry, GNSS leveling, and satellite gravity – from spaceborne, airborne, terrestrial, and marine platforms. This facilitates the precise computation of land-sea unified Complete Bouguer gravity anomalies/disturbances, vertical deflections, and gradients, as well as unified Classical Bouguer and Isostatic anomalies/disturbances.

Gravity exploration analytical modeling using multi-source heterogeneous data can be achieved via the following four-step workflow:

(a) Define Scope and Model Type: Delineate the target region, computation surface, and exploration model type. Acquire all available gravity and other geodetic data within and surrounding the target region.

(b) Generate Target Field Grid Model: Utilize modules from the subsystem “High-Precision Gravity Field Approximation and Full-element Modeling” to compute a high-resolution grid model of the target field element on the specified computation surface.

(c) Compute Terrain Effect Grid Model: Employ modules from the subsystem “Computation of Diverse Terrain Effects on Various Gravity Field Elements” to derive a high-resolution grid model of the terrain effect consistent with the chosen exploration model.

(d) Synthesize Exploration Model: Directly subtract the terrain effect grid [Step (c)] from the gravity field element grid [Step (b)]. The result is a gravimetric exploration model that fully integrates all available gravity field data.

(2) Summary of Advantages

This scheme deeply fuses multi-source heterogeneous geodetic data within a unified mathematical framework, strictly adhering to model definitions to achieve high-precision analytical modeling. By circumventing traditional gravity reduction, continuation, and gridding operations, it effectively mitigates issues such as signal attenuation, non-analytical distortion, and error propagation inherent in conventional methods.