Subglacial hydrological connectivity within the Byrd Glacier catchment, East Antarctica

Abstract

Ice, Cloud and land Elevation Satellite (ICESat) repeat-track laser altimetry has identified 17 sites within the Byrd Glacier catchment, East Antarctica, where rapid ice-surface height changes have occurred, which have been interpreted as evidence for 'active' subglacial lakes. Here we present evidence from a new radio-echo sounding (RES) survey at 11 of these locations to understand the bed conditions associated with the proposed hydrological activity. At none of the sites examined did we find evidence in support of substantial pooled basal water. In the majority of cases, along-track RES bed reflection amplitudes either side of the locations of surface height change are indistinguishable from those within the features. These results indicate that, in most cases, hypothesized 'active' lakes are not discrete radar targets and are therefore much smaller than the areas of surface height change. In addition, we have identified three new relatively large subglacial lakes upstream of the region where most 'active' subglacial lakes are found, in an area where the hydraulic gradient is significantly lower. Our results suggest that substantial and long-lasting basal water storage in the Byrd Glacier catchment occurs only under low hydraulic gradients, while coast-proximal sites of hydraulic activity likely involve small or temporary accumulations of basal water.

Missing Evidence of Widespread Subglacial Lakes at Recovery Glacier, Antarctica

“…However, it is inconsistent with the hydraulic potential that is based on reasonable data. Similar to the study of Wright et al (), our findings are consistent with criticism of interpreting surface lowering as a definitive indicator of lake drainage.…”

Possible groundwater dominance in the subglacial hydrology of ice sheet interiors: example at Dome C, East Antarctica

“…Forieri et al, 2004;Tikku et al, 2005;Parrenin et al, 2007;Carter et al, 2009b). Dome C is also 110 located in an area of high "radar lake" density and paucity of "active lakes" (Wright et al, 2014), which was advantageous for hypothesis testing. A critical input for the numerical model was the availability of lower-error melt rates in the study area (Carter et al, 2009b).…”

“…mountain glaciers and ice streams), relatively much less has been done to show how meltwater transports under the interiors of continental ice sheets like the East Antarctic Ice Sheet (e.g. Carter et al, 2009a;Wright et al, , 2014. Subglacial melt rates under the vast majority of the interiors of these kinds of ice sheets are estimated to be very low compared to the higher melting zones underneath ice streams (<10 mm 25 yr -1 ; Pattyn, 2010).…”

“…Boulton et al, 1995;Piotrowski, 1997;Person et al, 2007a;Lemieux et al, 2008). 35 The presence of large and small subglacial lakes underneath the East Antarctic Ice Sheet (and West Antarctic) is now well established (Siegert et al, 2005a;Smith et al, 2009;Wright and Siegert, 2014). Originally, subglacial lakes were thought of as long-lasting stable environments whose behavior impacted only the overlying ice and received their water entirely from local sources (Tikku et al, 2005).…”

“…When this same criterion is applied to radio-echo sounding data from "active lakes" (with the exception of Subglacial Lake Mercer; Carter et al, 2007;Fricker and Scambos, 2009;Fricker 55 et al, 2007Fricker 55 et al, , 2010 it often fails at least one if not multiple tests for detecting "radar lakes" such as hydraulic flatness, specularity, and brightness relative to its surroundings (e.g. Smith et al, 2009;Christianson et al, 2012;Siegert et al, 2014;Wright et al, 2014). Conversely, satellite and GPS data collected over most "radar lakes" (with the exception of the Adventure Trench lakes of Wingham et al (2006) show no detectable change.…”