(a) Surface elevation change between 2002 and 2009 as measured by ATM laser altimetry on the across-flow Smith Glacier (SG) transect delimited by S-S′ shown in Fig. 1a. (b) The 2002 and 2009 ice surface and bottom MCoRDS profiles of SG along the transect delimited by S-S′ in Fig. 1a. The hydrostatic floatation levels were found by taking freeboard elevation to be 0.12 of ice thickness, which was inferred from floating ice in Figs 3b and 4b; and taking sea surface to be at −33.9 m relative to the WGS84 ellipsoid, which was found from ATM 2009 measurements of ocean surface height in front of the Dotson Ice Shelf. The 2002 ice bottom appears partially dotted at some locations due to the lower density of available measurements there. (c) Ice surface and bottom along-flow profiles following the entire 2004 AGASEA trajectory shown in Fig. 1b. In this and subsequent figures the vertical grey lines mark grounding line locations. The 1996 grounding line location is taken as the origin of the x axis representing the distance along the flight path, and is indicated by a shorter grey line when bed topography is not available at its location.