GOCE data products
The objective of GOCE is the provision of a high-accuracy, high-resolution model for the static part of Earth’s gravity field. This model is basically derived from gradiometer (SGG) and GPS tracking (SST) observations.
The use of GOCE data products mainly fall in five different themes:
- Sea level change studies
For certain applications within these themes, Level-1 data products can be used directly, e.g., calibrated SGG observations in certain solid-Earth studies. However, in certain other applications, a spherical harmonic expansion or a linear function of this can be used directly, e.g., in ocean current derivation from satellite radar altimetry, and in precise orbit computations.
However, for some GOCE impact studies, especially Level-2 products, other representation forms are needed, some of which may be derived by linear transformations or derivations from a spherical harmonic expansion.
Three stages to estimate gravity and the geoid
The complex data processing from engineering numbers to a gravity product can be divided into three consecutive stages:
|Data Level||Processing Steps|
|Level 0 -> 1b||Real time orbits from GPS|
|Determination of gravity gradients, common mode accelerations and attitude information|
|(e.g. orientation and angular velocities)|
|Combined analysis of accelerometers, GPS, star sensors, attitude and drag controls|
|Level 2||Determination of the best possible set of spherical harmonic coefficients of the Earth’s gravity|
|field and precision orbits, including quality parameters for orbit and for the set of coefficients.|
|As derived products, a geoid model and a gravity anomaly model are determined|
|Level 3 and higher||The level 2 data products serve as input for the further fields of science and application|
|(e.g. solid-Earth physics, oceanography, ice research, geodesy and sea level studies)|