Motion of major ice-shelf fronts in Antarctica from slant-range analysis of radar altimeter data, 1978-98

Abstract

Slant-range analysis of radar altimeter data from the Seasat, Geosat and European Remote-sensing Satellite (ERS-1 and -2) databases is used to determine barrier location at particular times, and estimate barrier motion (km a 1) for major Antarctic ice shelves. The analysis covers various multi-year intervals from 1978 to 1998, supplemented by barrier location maps produced elsewhere for 1977 and 1986. Barrier motion is estimated as the ratio between mean annual ice-shelf area change for a particular interval, and the length of the discharge periphery. This value is positive if the barrier location progresses seaward, or negative if the barrier location regresses (break-back). Either positive or negative values are lower-limit estimates because the method does not detect relatively small area changes due to calving or surge events. The findings are discussed in the context of the three ice shelves that lie in large embayments (the Filchner-Ronne, Amery and Ross Ice Shelves), and marginal ice shelves characterized by relatively short distances between main segments of grounding line and barrier (those in the Dronning Maud Land sector between 010.1 ° W and 032.5° E, and the West and Shackleton Ice Shelves). The ice shelves included in the study account for approximately three-quarters of the total ice-shelf area of Antarctica, and discharge approximately two-thirds of the total grounded ice area.