CaVaMuMi: Calibration and Validation of altimeter observations and models by means of global multi-mission crossover analysis
- (Deutsches Geodätisches Forschungsinstitut der Technischen Universität München (DGFI-TUM))
The project will conduct inter-calibrations of contemporaneous altimeter systems based on extended crossover analyses on a global scale. For the period from 1992 up to the present, the study performs calibration and validation of all available altimeter missions. The focus is set to Jason-3 and Jason-2. However, all other missions will also be included: past missions (TOPEX, Jason-1), as well as external missions (ERS-1/2, Envisat, Saral, GFO, IceSat, HY-2A, Cryosat-2, Sentinel-3) and future missions (i.e., Jason-CS, as soon as they are available).
The study will use an extended multi-mission crossover analysis approach in order to assess the performance of each mission. The cross-calibration is realized globally by adjusting an extremely large set of single- and dual-satellite sea surface height (SSH) crossover differences performed between all contemporaneous altimeter systems. The total set of crossover differences creates a highly redundant network and enables a robust estimate of radial errors with a dense and rather complete sampling for all altimeter systems analyzed. Iterative variance component estimation is applied to obtain an objective relative weighting between altimeter systems with different performance.
The analysis yields time series of radial errors of each mission and can be used to derive inter-mission biases, to identify potential altimeter drifts, as well as to extract information on the quality of precise orbit determination (POD) and geophysical corrections (e.g., wet tropospheric errors). In addition, a long-term data record will be constructed allowing for precise sea level monitoring on different temporal and spatial scales.