Gravity Anomaly Assessment Using GGMS and Airborne Gravity Data Towards Bathymetry Estimation

Abstract

ABSTRACT:The Earth's potential information is important for exploration of the Earth's gravity field. The techniques of measuring the Earth's gravity using the terrestrial and ship borne technique are time consuming and have limitation on the vast area. With the space-based measuring technique, these limitations can be overcome. The satellite gravity missions such as Challenging Mini-satellite Payload (CHAMP), Gravity Recovery and Climate Experiment (GRACE), and Gravity-Field and Steady-State Ocean Circulation Explorer Mission (GOCE) has introduced a better way in providing the information on the Earth's gravity field. From these satellite gravity missions, the Global Geopotential Models (GGMs) has been produced from the spherical harmonics coefficient data type. The information of the gravity anomaly can be used to predict the bathymetry because the gravity anomaly and bathymetry have relationships between each other. There are many GGMs that have been published and each of the models gives a different value of the Earth's gravity field information. Therefore, this study is conducted to assess the most reliable GGM for the Malaysian Seas. This study covered the area of the marine area on the South China Sea at Sabah extent. Seven GGMs have been selected from the three satellite gravity missions. The gravity anomalies derived from the GGMs are compared with the airborne gravity anomaly, in order to figure out the correlation (R 2 ) and the root mean square error (RMSE) of the data. From these assessments, the most suitable GGMs for the study area is GOCE model, GO_CONS_GCF_2_TIMR4 with the R 2 and RMSE value of 0.7899 and 9.886 mGal, respectively. This selected model will be used in the estimating the bathymetry for Malaysian Seas in future.

Comparison of Gravity Anomalies from Recent Global Geopotential Models with Terrestrial Gravity and Airborne Gravity over Johor Region

“…where ggrav(ggm) is residual gravity anomaly, ggrav is free air gravity anomaly obtained from existing terrestrial observation data and gggm is gravity anomaly derived from GGM by using EGMLab software. The EGMLab software is a scientific software for determining the gravity and gradient components from the global geopotential as the model has been represented by the spherical harmonic coefficient that defines the potential of gravitational in the spectral domain [12]. The specific gravity-related information such as gravity anomaly (g) can be computed using spherical harmonic coefficients as follows [4];…”

Deriving a Geoid Undulation Network over Egypt by Merging Data of Different Global Geo-Potential Models

“…(N i ) Values can be calculated by several Global Geo-potential Models (GGMs). GGM is a model that is being represented by the spherical harmonic coefficient that defines the potential of gravitational in the spectral domain (Tugi et al, 2016). Egypt has an area of up to one million km 2 and due to the limited input data for different GGMs.…”

Correlation Relationship between Different GGMs Data over Egypt

“…Four gravity satellite missions collected data over the last two decades to develop different GGMs as following ( Tugi et al, 2016;Tarek, 2018;Tarek, 2019-b );…”

“…-CHAllenging Minisatellite Payload (CHAMP) which classified as satellite-only models. Tugi et al, (2016) explained the meaning of expressions as following;…”

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Hi = hi -Ni(1)Global Geo-potential Model (GGM) defines the potential of gravitational in the spectral domain by the spherical harmonic coefficient (Tugi et al, 2016). It is used to calculate the undulation height value (Ni).

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