9:00 AM - 9:15 AM
[SGD01-01] The Airborne Gravity Survey for Development of a New Precise Gravimetric Geoid Model in Japan
Keywords:Airborne gravity survey, Geoid, Gravity
The gravimetric geoid model is constructed by combining the satellite gravity data and the terrestrial gravity data (land and shipborne measurements), the altimetry-derived marine gravity data. The satellite gravity data is used to determine the long wavelength components of the geoid undulations, while the terrestrial gravity data and the altimetry-derived marine gravity data are used to determine the medium and short wavelength components. Several attempts have been made to improve the accuracy of the gravimetric geoid model in Japan, such as adding new satellite gravity data and improving the method of computing gravimetric geoid model (Kuroishi, 2009; Matsuo and Kuroishi, 2020). However, due to the lack of land gravity data in mountainous areas and the low accuracy of shipborne marine gravity data in coastal areas, large discrepancies between the gravimetric geoid models and GNSS/leveling geoid heights occur in these areas (Matsuo, 2017; Matsuo and Kuroishi, 2020). In addition, most of the land gravity data was observed more than 30 years ago, and the observation locations are often obtained from maps. This inaccuracy in location information may cause errors in the gravimetric geoid model.
Therefore, in order to solve these problems, the Geospatial Information Authority of Japan (GSI) has started airborne gravity survey since 2019. The airborne gravity survey can efficiently collect homogeneous gravity data for everywhere, even in mountainous or coastal areas. Since the aircraft is equipped with a GNSS receiver, it is possible to obtain position data with centimeter accuracy. Furthermore, the obtained data has the advantage of higher spatial resolution (spatial wavelength about 10km) than the satellite gravity data. The plan is to collect the airborne gravity data for all over Japan except for the outlying islands by 2023 and to build a precise gravimetric geoid model accurate to 3 cm by combining the airborne gravity data with existing gravity data in 2024.
As of December 2020, approx. 50% of data collection of planned survey lines are completed. Comparing the airborne gravity data with EGM2008 model gravity data, there is a tendency of large gravity difference in some mountainous and coastal areas. In particular, there are gravity differences of over 10 mGal in Kashimanada Sea, Osaka Bay, and Akaishi Mountain Range. It is assumed that the airborne gravity could detect the certain gravity which is not covered by EGM2008.
In this presentation, we will report the progress of the measurement, design of survey lines, data processing, and quality assessment.
References
1) Kuroishi, Y. (2009). Improved geoid model determination for Japan from GRACE and a regional gravity field model, Earth Planets Space 61, 807–813.
2) Matsuo, K., Kuroishi, Y. (2020). Refinement of a gravimetric geoid model for Japan using GOCE and an updated regional gravity field mode, Earth Planets Space 72, 33.
3) Matsuo, K. (2017). Development of a precise gravimetric geoid model for constructing new national height reference system, Heisei 29 nendo kokudo koutsu sho kokudo gijutsu kennkyukai ronbunshu 277 – 282. (Japanese).
Therefore, in order to solve these problems, the Geospatial Information Authority of Japan (GSI) has started airborne gravity survey since 2019. The airborne gravity survey can efficiently collect homogeneous gravity data for everywhere, even in mountainous or coastal areas. Since the aircraft is equipped with a GNSS receiver, it is possible to obtain position data with centimeter accuracy. Furthermore, the obtained data has the advantage of higher spatial resolution (spatial wavelength about 10km) than the satellite gravity data. The plan is to collect the airborne gravity data for all over Japan except for the outlying islands by 2023 and to build a precise gravimetric geoid model accurate to 3 cm by combining the airborne gravity data with existing gravity data in 2024.
As of December 2020, approx. 50% of data collection of planned survey lines are completed. Comparing the airborne gravity data with EGM2008 model gravity data, there is a tendency of large gravity difference in some mountainous and coastal areas. In particular, there are gravity differences of over 10 mGal in Kashimanada Sea, Osaka Bay, and Akaishi Mountain Range. It is assumed that the airborne gravity could detect the certain gravity which is not covered by EGM2008.
In this presentation, we will report the progress of the measurement, design of survey lines, data processing, and quality assessment.
References
1) Kuroishi, Y. (2009). Improved geoid model determination for Japan from GRACE and a regional gravity field model, Earth Planets Space 61, 807–813.
2) Matsuo, K., Kuroishi, Y. (2020). Refinement of a gravimetric geoid model for Japan using GOCE and an updated regional gravity field mode, Earth Planets Space 72, 33.
3) Matsuo, K. (2017). Development of a precise gravimetric geoid model for constructing new national height reference system, Heisei 29 nendo kokudo koutsu sho kokudo gijutsu kennkyukai ronbunshu 277 – 282. (Japanese).