The Airborne Gravity Survey for Development of a New Precise Gravimetric Geoid Model in Japan

Abstract:

The Geospatial Information Authority of Japan (GSI) has started an airborne gravity survey since July 2019. A Micro-g LaCoste TAGS-7 Dynamic Gravity Meter on board the Cessna 208 is used for collecting airborne gravity data. By 2024, a new gravimetric geoid model for Japan will be developed by combining the airborne gravity data and the existing surface gravity such as terrestrial, marine, and satellite gravity data. The final goal is to build a geoid model accurate to 3 cm in standard deviation.

Since the existing gravity data in mountainous and coastal area is quite sparse in Japan, we expect that it can be filled with the airborne gravity data with a constant quality. In 2019, we made a study of the analysis method and quality assessment of the gravity data collected by the airborne gravimeter. From the comparison between the airborne gravity data and the upward-continued surface gravity, it found that the difference between them is large in the area less than 40 km from the coast while that became small in the area over 40 km away from the coast. It means that the sparse area of existing coastal gravity data which should be filled by the airborne gravimetry is 40 km from the coast.

The airborne gravity survey is a challenging project for us, but thanks to great supports of the colleagues of the National Geodetic Survey (NGS) in US, we managed to start the measurement and data processing. In this presentation, we will report the progress of the measurement, data processing, quality assessment, and our future vision.