GTeC—A versatile MATLAB® tool for a detailed computation of the terrain correction and Bouguer gravity anomalies

• A versatile MATLAB code for gravity terrain correction is presented.
• It goes beyond the limits of other available programs for terrain correction.
• Absolute or free air data at land/sea surface are accepted using more nested DEMs.
• It exploits a formula modeling a tessellated network formed by triangular polyhedra.
• Accurate terrain correction is allowed in presence of steep topographic gradients.

Gravity Terrain Correction (GTeC) is a versatile MATLAB® code for terrain correction aimed to this purpose and capable of going beyond the limits of other public domain codes targeted to this aim.It runs with input gravity data (absolute measurements or free air anomalies) at the land/sea surface and with one or more DTMs (indifferently gridded or scattered) at different detail levels. Each of them can be used to calculate the gravity contribution of a concentric terrain zone around the point station with increasing resolution toward the center. The user can choose between two alternative algorithms for terrain modeling. The simplest one considers each grid point as the flat top of a squared prism. For areas closer to the point station a second algorithm can be chosen to better approximate the relief, with respect to others formulas, by means of a tessellation based network formed by triangular prisms. A more precise terrain correction is therefore achieved, especially in presence of high topographic gradients or just outside the sea/land boundaries. In the last case a suitable algorithm was expressly devised to fit the tessellation based network to the irregular trend of the coastline.GTeC calculates also free air anomalies and both plate and curvature corrections, providing also a complete graphic output including topography, free air anomalies, plate correction, total terrain correction, Bouguer anomalies and the terrain effect due to each computational zone.GTeC speeds up CPU times taking advantage from the parallel computing functions and from the vectorization code, both exploited in MATLAB®. Two code versions of GTeC (for normal or parallel computation), executable under MATLAB environment (pcode), are fully available as public domain software.The results of a synthetic case, of a real case at the regional scale and of a microgravity survey carried out at a short scale, are here presented.