GOCE data product verification in the Mediterranean Sea

ESA's General Ocean Circulation Experiment (GOCE) mission is anticipated to generate Level 2 data products such as global geopotential model with geoid undulation accuracy of 1 cm RMS with a spatial resolution of 130 km or longer. We propose a calibration and validation effort to verify GOCE measurements and data products including the Level 2 geopotential model in the Mediterranean Sea, a water body of 4000 km by 1000 km area. This study used the POCM_4B ocean dynamic topography and the dynamic topography computed using XBT data from NOAA/NODC WOA 2001 data to aid the evaluations of recent geoid models from CHAMP and GRACE. Altimetric mean sea surfaces (ERS-2 and TOPEX) are also used globally and regionally (in the Mediterranean Sea) to assess accuracy of current geoid models. Preliminary monthly comparisons of the GRACE geoid for 7 months using the WOA01 data show good agreement globally and reasonable agreement in the Mediterranean Sea. To validate the GOCE gravity tensor data, accurate knowledge of geoid undulation over Mediterranean Sea, is needed via an appropriate upward continuation to the GOCE altitude. The inaccurate in situ regional geoid could present a problem for calibration and validation of gravity mapping sensors such as GOCE.