Radar altimetry measurements over antarctic ice sheet: A focus on antenna polarization and change in backscatter problems

In this paper, we investigate the impact of the error due to the penetration of the altimetric wave within the snowpack. The phenomenon has two different impacts. The first one, due to temporal change in snow characteristics, affects the ice sheet volume trend as derived from altimetric series. The second one, because of both the anisotropy of the ice sheet surface properties and of the linear antenna polarization, introduces a difference in measurements at crossover points. These two phenomena are the cause of what are probably the most critical limitations to the interpretation of long-term altimetric series in term of mass balance and to the comparison between or data fusion of different missions. Moreover, they will lead to the largest error when comparing data from EnviSat with data from CryoSat, because of the different orbits, or with data from AltiKa, because of the different radar frequencies.