Accuracy assessment of available airborne gravity data in the central western desert of Egypt

Abstract

Abstract In the current study, the accuracy of airborne gravity data is evaluated based on the most recent Global Geopotential Models (GGM) and terrestrial gravity data to find out to what extent these data are acceptable to be used in multi-applications (e. g., geodesy and geophysics). To achieve this goal, the remove-compute-restore (RCR) scheme, upward, and downward continuation operational methods (least square collocation and fast Fourier transform procedures) are applied. The airborne gravity data had been acquired by the Egyptian Nuclear Material Authority (ENMA) in the central-western desert for geological applications. Firstly, three GGMs models (EGM2008, EIGEN-6C4 and XGM2019e up to various degrees) are used to compare with the free-air airborne gravity anomaly, The EGM2008 model up to degree 720 produces the smallest mean and STD difference values with 2.59 and 3.07 mGal, respectively. The terrestrial gravity data are compared with the airborne gravity anomaly at both flight and ground levels. In-flight level, the terrestrial gravity data are upward continued to the flight level and compared with the airborne gravity anomaly. The statistical results show that the mean and STD differences are about 4.2 and 0.75 mGal, respectively. While in-ground level evaluation, two operational techniques are used to downward continue the airborne gravity data (Fast Fourier Transform (FFT) and Least Squares Collocation (LSC)). The combined Satellite model EGM2008 up to degree 720 and SRTM 30 m are used to remove and restore the long and short-wavelength information. It is observed that the collocation gives better statistical results than FFT with mean and STD difference values are about 3.13 and 1.13 and mGal, respectively.