CoAuthors

Matthias Raynal (CLS, France); Ghita Jettou (CLS, France); Nicolas Picot (CNES, France); Pierre Femenias (ESA, Italy)

Data quality of altimetry missions is excellent over open ocean, but sea level measurements are tricky difficult to apprehend when approaching coasts. This is partly due to heterogeneous surface reflections within the altimeter footprint (over both ocean and land surfaces), as the altimeter beam illuminates a circle of ocean or land surfaces with a 3 to 10 km radius, depending on the sea state, the wave height or the corrugated land. Radiometers are impacted from 10km (SARAL) to 40km (Jason) to coast. Geophysical corrections’ sensibility to shore distance can also impact the computed sea level.

Conventional altimetry (Jason-3 in Ku-band, SARAL in Ka-band) and Delay Doppler Mode (Sentinel-3A SARM) methods are used in altimetry with different footprint and instrumental noise. Thanks to a reduced footprint coupled with a lower instrumental noise, SARAL and Sentinel-3 should provide improved sea level observations over coastal regions compared to Jason-3. We will focus on how different sources of error () interact during SLA computations for these three missions.

This presentation aims overviewing the performances of different altimetry missions over coastal areas, through the analysis of various data from Sentinel-3A, Jason-3, and SARAL/AltiKa.