Glaciers worldwide are subject to large seasonal changes in boundary conditions. This seasonal variation provides a wonderful natural experiment to study the reaction of glaciers to external forcings. This is particularly important in the case of tidewater and outlet glaciers, where the ice discharge directly contributes to mass loss and sea level rise. Seasonality in ice flow can be driven both by seasonal changes in basal friction and large fluctuation in terminus position. We will take a closer look at Sit’ Tlein (Hubbard Glacier) in Alaska, where both drivers are in effect for the same glacier, resulting in a curious pattern with a double-peaked seasonal cycle.  

Reading:

Moon, T., I. Joughin, B. Smith, M. R. van den Broeke, W. J. van de Berg, B. Noël, and M. Usher (2014), Distinct patterns of seasonal Greenland glacier velocity, Geophys. Res. Lett., 41, 7209–7216,

doi:10.1002/2014GL061836.