Vincent Marieu (EPOC-OASU, France); Stéphane Calmant (LEGOS-OMP, France); Frédérique Seyler (ESPACE-DEV, France)

The definition of altimetry virtual stations over inland water bodies requires a very specific processing composed of a refined selection of valid data for estimating water levels and eventually the correction of hooking effect. The Multi-mission Altimetry Processing Software (MAPS) offers the opportunity to end-user to define their own virtual stations using the altimetry data contained in the Geophysical Data Records (GDRs) of most of nadir-looking radar altimetry missions (i.e., Envisat, Jason-1, Jason-2, Saral, and Jason-3), the recently reprocessed ones as ERS-2 (both REAPER and CTOH reprocessing), and the new SAR altimetry missions (CryoSat-2 and Sentinel-3). It also allows the reading of IceSAT laser data (hdf format). Once achieved a coarse selection of the altimetry measurements present in the sudy zone using a kml file defined with Google Earth, altimetry heights are computed using the geophysical and environmental corrections for different type of surface (rivers and small lakes, great lakes, ocean, and coastal areas). A graphical user interface allows to visualize not only the altimetry heights derived from the different retracked ranges available for each mission (e.g., Ocean, Ice-1, Ice-2, Sea Ice, MLE-3) inside the study area, but also any corrections used and other parameters (e.g., backscattering coefficients) that can be useful for selecting the valid altimeter heights. Correction of the hooking effects can be performed on the selected or a part of the selected data at any cycle. The selection of the valid data can be saved at any time and reloaded. Time-series of altimeter heights are then computed based on the user's selection of the valid data and can be exported. This software, developed as a collaboration between LEGOS-OMP, GET-OMP, and EPOC-OASU will be son available on the CTOH website: htpp://ctoh.legos.obs-mip.fr.