For the following comparison we use two SMOS sea ice products of the University of Hamburg (UH) and University of Bremen (UB). Both products have been obtained from the respective websites, and no modifications have been applied. Thus, they represent the retrieval algorithms as described in Tian-Kunze et al. (2014) and Huntemann et al. (2014). The sea ice thickness products were derived from SMOS data based on the base line processor version 505 operational in March 2014.