High Level Data Processing Issues and Products

The SSALTO/DUACS system is the main multi-mission altimeter data center used today for operational oceanography. It aims to provide directly usable, high quality near real time and delayed mode (for reanalyses and research users) altimeter products to the main operational oceanography and climate centers in Europe and worldwide. Main processing steps are product homogenization, data editing, orbit error correction, reduction of long wavelength errors, production of along track and maps of sea level anomalies. Major progress has been made in higher level processing issues such as orbit error reduction (e.g. Le Traon and Ogor 1998), intercalibration and merging of altimeter missions (e.g. Le Traon et al. 1998; Ducet et al. 2000; Pascual et al. 2006). The SSALTO/DUACS weekly production moved to a daily production in 2007 to improve timeliness of data sets and products. A new real time product was also developed for specific real time mesoscale applications.

The mean dynamic topography (MDT) is an essential reference surface for altimetry. Added to the sea level anomalies, it provides the absolute sea level and ocean circulation (see previous section). After a preliminary MDT computed in 2003, a new MDT, called RIO-05, was computed in 2005. It is based on the combination of GRACE data, drifting buoy velocities, in-situ T,S profiles and altimeter measurements. The MDT was tested and is now used by several GODAE modelling and forecasting centers. It has a positive impact on the ocean analysis quality and forecast skill. An updated version was recently delivered (CNES-CLS09). Major improvement is expected soon with the use of data from the GOCE mission.

0 0

Post a comment