**2.5 The operation ice bridge data**

The Operation IceBridge (OIB) science data are used to validate the results of the sea ice thickness inversion process. IceBridge L4 sea ice freeboard height, snow depth, and ice thickness data (IDCSI4, IceBridge L4 Sea Ice Freeboard, Snow Depth, and Ice Thickness) are used to validate the sea ice freeboard and thickness inversion results of this study [21, 22]. The March 2013 OIB flight path is shown in **Figure 4**.
