We compare passive microwave-derived sea ice concentrations with ship-based observations of sea ice concentration (OBS). We focus on different retrieval algorithms that are based on Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) measurements. OBS are collected according to the Antarctic Sea Ice Processes and Climate (ASPeCt) program. We assess the quality of the satellite data by calculating correlation coefficient, root-mean-square-deviation (RMSD) and bias with respect to ASPeCt observations of sea ice concentration. All retrieval algorithms compared in this study, Comiso Bootstrap (BST), NASA-Team 2 (NT2) and Artist Sea Ice (ASI), show correlation coefficients above 0.8 for all dates considered (N = 313). BST and ASI do not have a significant bias, but NT2 has a bias of 8 \%. RMSD values are different for different seasons, but generally, Comiso BST has the lowest RMSD (< 13 \%).