For the purpose of marine geoid modeling and many other
geodetic and geophysical applications, a marine gravity map
around Egypt is established by the integration of gravity datprovided by satellite altimetry and shipborne gravimetric
observations. Firstly, the collected shipborne data were compared with GO_CONS_GCF_2_TIM_R6 and XGM2019e GGMs
and with SSv29.1 and DTU17 altimetry models. Then, a prerefinement of ship marine surveys was done with a rigorous
condition, in which a number of 6525 points have beeremoved from the dataset. After that, 87709 points were
deducted from the pre-filtered shipborne dataset to fit the
study area and the cross-validation approach with the krigininterpolation algorithm were applied. A rigorous level of confidence was decided in this step where the points which havdifferences between the estimated and the observed valuemore than twice the STD of the residuals were removed until
the STD reached a value less than 1 mGal. Finally, the filtereshipborne gravity data were combined with DTU17 (the besevaluation model) using the least-squares collocation technique
(LSC). The final gravity map was tested using 8000 randomly chosen shipborne stations, which were not included
when applying LSC, revealing the significant enhancement
gained after the integration process. |
