The backscatter coefficient, sigma naught, is computed from the power of the return pulse of the altimeter. It can be related to wind speed. Empirical models establish a relation between the wind speed, and the sea surface backscatter coefficient and significant wave height. It can also provide information about the surface upon which the radar wave reflected (e.g. snow or bare earth, even the kind if ice, the fact there are crevasses in ice shelves,…)

 

ku_ocean_bscat_coeff_ocean_sm s_ocean_bscat_coeff_ocean_sm
ku_ocean_bscat_coeff_land_sm s_ocean_bscat_coeff_land_sm
fig 1. Sigma0 in Ku and S band (from Envisat GDR cycle 40) measurements (top over ocean, bottom over lands). Water, ices and lands give very different values of these backscatter coefficients, since those surfaces have different reflexivity. These maps are drawn using the BRAT.