Cryosphere
One of the key questions in understanding the consequences of our changing climate is determining how the contribution to sea-level rise of the mass lost from ice sheets will evolve over the 21st century. Current estimates of Antarctica’s future contribution to sea level rise vary widely, from 0.1 m annually to more than 1 m by the year 2100. The main source of uncertainty in these projections is the difficulty of modeling the evolution of ice-sheet dynamics (Figure 1) due to poorly constrained oceanic and atmospheric forcings, or to the lack of boundary conditions such as bedrock topography (Figure 2) and ocean bathymetry. We combine remote sensing observations of the ice sheets with numerical modeling to fill these important gaps in our knowledge.
Ice sheets get “out of balance” when mass loss exceeds accumulation. As the climate warms, Antarctica’s grounding lines (boundaries between grounded and floating ice) have been retreating, resulting in increased ice discharge to the ocean when the retreat is on bedrock that deepens farther inland. The (currently poorly unknown) bedrock topography plays a crucial role in modulating the ice-sheet motion.
We are exploring the use of prospective simulations to plan airborne radar-sounding campaigns and to design a spaceborne radar sounding mission to fill the most important gaps in our knowledge. A VHF radar would detect the ice sheet bedrock and surface, along with large interglacial layers marked by discontinuities in dielectric properties. Such a radar can also measure extensive thinning of floating ice shelves due to enhanced ocean-induced submarine melting as water temperatures rise or warm waters intrude the cavities under the floating shelves.
Ala Khazhendar
Received a Ph.D. in geophysical sciences from the Université Libre de Bruxelles, Belgium. After a postdoc at the University of Cambridge, U.K., he joined JPL as a scientist.
His research combines remote sensing observations with numerical modeling to understand processes of ice-ocean interactions in Antarctica and Greenland that affect the stability of ice shelves and marine-terminating glaciers.
CL#24-5887