Realization of WHS Based on the Static Gravity Field Observed by GOCE

The paper deals with a determination of W ₀ as well as testing of geoid candidates for a realization of the World Height System using the GOCO03S satellite-only geopotential model. The W ₀ values are estimated for two different altimetric mean sea surface models (DTU10_MSS and MSS_CNES_CLS2011) using four different global geopotential models (GGMs), namely GOCE-DIR2 or GOCO03S satellite-only GGMs, and EGM2008 or EIGEN-6C combined GGMs. In all cases the impact of including polar regions into the integration area is presented.

The second part studies how the high-degree combined GGMs or local gravimetric geoid models correspond to the static gravity field observed by GOCE. The nonlinear diffusion filtering is used to reduce the stripping noise of the geopotential evaluated from the GOCO03S model up to degree 250. On lands, the geopotential is evaluated at 3D positions of the local (national) gravimetric-only geoid models, namely USGG-2012 in USA, CGG-2010 in Canada, AGQG-2009 in Australia, and NZGeoid09 in New Zealand, otherwise at 3D positions of the EIGEN-6C or EGM-2008 geoid models. At oceans, the geopotential is filtered on the DTU10 mean sea surface whose 3D position is precisely provided by satellite altimetry. Apart from high mountainous areas, the smoothed geopotential on the considered geoid models shows good agreement with GOCO03S, i.e. with the low-frequency part of the gravity field precisely observed by GRACE/GOCE. At the same time the filtered satellite-only mean dynamic topography is provided specifying its relation to the geoid models at coastal areas.