Research On Sea Area Airborne Gravity Survey Technology And Geoid Rapid Construction Method

Airborne gravity measurement is not restricted by the survey area conditions,and able to obtain uniformly distributed high-precision gravity field data efficiently.It is widely used in geological research,exploration of petroleum,natural gas,mineral resources,and geoid survey.The geoid is the gravitational equipotential surface that coincides with the global average sea level without tide and extends to the interior of the continent.It is the datum level of space elevation.The high-precision local geoid provide important basic spatial information for the research and application of oceanography,geomatics,seismology,geophysics and other related earth sciences.The geoid is closely related to the earth's gravity field model.The determination of geoid is based on the potential theory of earth's gravity field.Large scale airborne gravity survey of sea area has carried out in China,and provids important basic data for the survey of geology,petroleum and gas resources.The use of existing airborne gravity data to construct geoid in the jurisdictional sea area has practical significance and can expand application direction of airborne gravity exploration.This thesis systematically summarizes the sea area airborne gravity measurement and data processing technology,discusses the sea area airborne gravity measurement aircraft selection and modification technology,carries out a comparative study on the calculation methods of ground GNSS base station,and summarizes the technical points and requirements of the sea area airborne gravity measurement system integration,testing,flight measurement,data processing and quality evaluation,which provide reference for airborne gravity measurement in the South China Sea and other seas.This thesis presents a fast approach for determining geoid using airborne gravity survey data of sea area.Based on the idea of removal-recovery method,using the minimum curvature method of the potential field to perform high precision downward continuation of the airborne gravity data,and obtain the corresponding disturbance potential field,which can be converted into geoid by the Brun formula.Compared with the Stokes integral,the transform in frequency domain provides higher processing efficiency and accuracy,which solves the problem of data missing and edge expansion in both downward continuation and vertical integration.EGM2008 model was used for simulating airborne gravity data,and the calculation results are equivalent to the accuracy of geoid derived from EGM2008.At the same time,airborne gravity data of GRAV-D plan is also selected for physical verification,and the calculation results are basically consistent with the accuracy of x GEOID18 B model,compared with EGM2008,the accuracy of calculated geoid is improved by about 4cm.Model verification and practical application verified the practicability of the method.Using this method and the measured airborne gravity data to construct geoid of certain sea area.The calculation results show that the maximum refined amount of geoid by the actual airborne gravity data is up to 17 cm.