JSG T.28

Introduction

he geometrical definition of the shape and numerical evaluation of the corresponding gravity signal of any given mass distribution express a central theme in gravity field modelling. Involving different theoretical and computational aspects of the potential field theory and including the element of interpreting the computed signal by comparing it with the observed gravity field, the specific research topic determines a characteristic interface between geodesy and geophysics.

Theoretical and methodological aspects of mass modelling concern a wide range of applications, from computing gravity anomalies and geoid to reducing satellite gradiometry data or solving an extended family of integral equations of the potential theory. Directly linked to real mass density distributions in the Earth’s interior, the problem of computing the potential function of given mass density distributions and its spatial derivatives up to higher orders defines the core of forward gravity field modelling, while also constituting an integral part of an inverse modelling flowchart in geophysics.

The availability of an abundance of terrestrial and satellite data of global coverage and increasing spatial resolution provides a challenging framework for revisiting known theoretical aspects and especially investigating computational limits and possibilities of forward gravity modelling induced by known mass distributions. Satellite observations provide global grids of gravity related quantities at satellite altitudes, global crustal databases offer detailed layered information of the shape and consistency of the Earth’s crust, while satellite methods produce digital elevation models that represent a continental part of the topographic surface with unprecedented resolution.

The current datasets enable the consideration of several theoretical, methodological and computational aspects of forward gravity field modelling. For instance, dense digital elevation models provide a unique input dataset that challenges the evaluation of precise terrain effects, especially in areas of very steep terrain. At the same time and due to the availability of new data, the complete theoretical framework that evaluates the gravity effect of a given distribution using analytical, numerical or spectral techniques emerges again at the forefront of research, examining both ideal bodies and real distributions. Finally, the existence of detailed information of the structure in the Earth’s interior provides an opportunity to revisit synthetic Earth reference models by computing the actual gravity effect induced by these distributions and validate it against the observed gravity signal obtained by the available gravity field models.

Objectives

• Examine new theoretical developments (numerical, analytical or spectral) in expressing the gravity signal of ideal geometric distributions.
• Perform validation studies of precise terrain effects over rugged mountainous topography.
• Compute the gravity effect of structures in the Earth’s interior and embed this effort in the frame of a synthetic reference Earth model.

Program of activities

• Participation in forthcoming IAG conferences with splinter meetings and proposed sessions.
• Preparation of joint publications with JSG members.
• Organization of a session at the Hotine-Marussi Symposium 2022.

Members

Dimitrios Tsoulis (Greece), chair
Carla Braitenberg (Italy)
Christian Gerlach (Germany)
Ropesh Goyal (India)
Olivier Jamet (France)
Michael Kuhn (Australia)
Pavel Novák (Czech Republic)
Konstantinos Patlakis (Greece)
Daniele Sampietro (Italy)
Matej Varga (Croatia)
Jérôme Verdun (France)