02194nas a2200265   4500008004100000022001300041245008000054210007000134300001200204490000700216520131900223653001201542653002101554653002201575653003701597653002301634100001901657700002101676700002401697700002001721700002801741700002601769700001501795856011801810       2019                        eng d  a0022143000aNon-linear glacier response to calving events, Jakobshavn Isbræ, Greenland0 aNonlinear glacier response to calving events Jakobshavn Isbræ Gr  a39–540 v653 aJakobshavn Isbræ, a tidewater glacier that produces some of Greenland's largest icebergs and highest speeds, reached record-high flow rates in 2012 (Joughin and others, 2014). We use terrestrial radar interferometric observations from August 2012 to characterize the events that led to record-high flow. We find that the highest speeds occurred in response to a small calving retreat, while several larger calving events produced negligible changes in glacier speed. This non-linear response to calving events suggests the terminus was close to flotation and therefore highly sensitive to terminus position. Our observations indicate that a glacier's response to calving is a consequence of two competing feedbacks: (1) an increase in strain rates that leads to dynamic thinning and faster flow, thereby promoting destabilization, and (2) an increase in flow rates that advects thick ice toward the terminus and promotes restabilization. The competition between these feedbacks depends on temporal and spatial variations in the glacier's proximity to flotation. This study highlights the importance of dynamic thinning and advective processes on tidewater glacier stability, and further suggests the latter may be limiting the current retreat due to the thick ice that occupies Jakobshavn Isbræ's retrograde bed.10acalving10adynamic thinning10aJakobshavn Isbræ10aterrestrial radar interferometry10atidewater glaciers1 aCassotto, Ryan1 aFahnestock, Mark1 aAmundson, Jason, M.1 aTruffer, Martin1 aBoettcher, Margaret, S.1 aDe La Peña, Santiago1 aHowat, Ian  uhttps://glaciers.gi.alaska.edu/content/non-linear-glacier-response-calving-events-jakobshavn-isbr%C3%A6-greenland01966nas a2200241   4500008004100000022001400041245010500055210006900160300001000229520113200239653001701371653002301388653004201411100002001453700002301473700002301496700001901519700001901538700002501557700002001582700002601602856009601628       2017                        eng d  a0022-143000aAcquisition of a 3 min, two-dimensional glacier velocity field with terrestrial radar interferometry0 aAcquisition of a 3 min twodimensional glacier velocity field wit  a1–83 a{\textless}p{\textgreater}Outlet glaciers undergo rapid spatial and temporal changes in flow velocity during calving events. Observing such changes requires both high temporal and high spatial resolution methods, something now possible with terrestrial radar interferometry. While a single such radar provides line-of-sight velocity, two radars define both components of the horizontal flow field. To assess the feasibility of obtaining the two-dimensional (2-D) flow field, we deployed two terrestrial radar interferometers at Jakobshavn Isbrae, a major outlet glacier on Greenland's west coast, in the summer of 2012. Here, we develop and demonstrate a method to combine the line-of-sight velocity data from two synchronized radars to produce a 2-D velocity field from a single (3 min) interferogram. Results are compared with the more traditional feature-tracking data obtained from the same radar, averaged over a longer period. We demonstrate the potential and limitations of this new dual-radar approach for obtaining high spatial and temporal resolution 2-D velocity fields at outlet glaciers.{\textless}/p{\textgreater}10aglacier flow10aglacier geophysics10aglaciological instruments and methods1 aVoytenko, Denis1 aDixon, Timothy, H.1 aHolland, David, M.1 aCassotto, Ryan1 aHowat, Ian, M.1 aFahnestock, Mark, A.1 aTruffer, Martin1 aDe La Peña, Santiago  uhttps://www.cambridge.org/core/product/identifier/S0022143017000284/type/journal{\_}article