An enhancement of the NASA Team sea ice concentration algorithm overcomes the problem of a low ice concentration bias associated with surface snow effects that are particularly apparent in Southern Ocean sea ice retrievals. The algorithm has the same functional form as the NASA Team algorithm, but uses a wider range of frequencies (19-85 GHz). It accommodates ice temperature variability through the use of radiance ratios as in the original NASA Team algorithm, and has the added advantage of providing weather-corrected sea ice concentrations through the utilization of a forward atmospheric radiative transfer model. Retrievals of sea ice concentration with this new algorithm for both the Arctic and Antarctic do not reveal the deficiencies present in either the NASA Team or Bootstrap algorithms. Furthermore, quantitative comparisons with infrared AVHRR data show that the enhanced algorithm provides more accurate ice concentrations with much less bias than the other two algorithms.