[G02-3] Regional gravity and geoid

[G02-3-01] An improved gravimetric geoid model for Japan based on the Stokes–Helmert scheme with a deterministically modified Stokes' kernel

^○Koji Matsuo¹, Takayuki Miyazaki¹, Basara Miyahara¹, Yuki Kuroishi² (1.Geospatial Information Authority of Japan, Ibaraki, Japan, 2.The University of Tokyo, Tokyo, Japan)

This study developed an improved gravimetric geoid model for Japan on a 1 * 1.5 arc-minute grid, based on the remove–compute–restore with Helmert's second method of condensation (the Stokes–Helmert scheme). A GOCE (the Gravity field and steady-state Ocean Circulation Explore)-related global geopotential model was used with 309,992 land gravity data and an updated altimetry-derived marine gravity model. To minimize the truncation error and appropriately combine each gravity data, the hybrid Meissl–Molodensky modified spheroidal kernel was employed with modification parameters regionally tuned. Thus, we created a gravimetric geoid model for Japan corresponding to GNSS/leveling geoid heights with a standard deviation of 5.91 cm, an improvement of 2.63 cm compared with the previous model (JGEOID2008). This remarkable improvement was particularly evident in the long-wavelength component of the geoid undulation. The north–south tilted trend of the difference between the gravimetric and GNSS/leveling geoid heights was reduced significantly from 0.18 to 0.06 ppm. Gravimetric geoid model improvements provide the possibility of generating a new standard and convention for the height reference system in Japan, currently realized by spirit leveling and tide-gauge observation.