The Potential Role of Anomalous Geothermal Flux for Enhanced Basal Melting and Suppressed Ice Velocity at Haynes Glacier, West Antarctica

In NASA’s MEaSUREs Ice Velocity Data, a distinctive 8.5km diameter patch of slow-moving to stationary ice (0-15m/year) can be observed near the grounding line of Haynes Glacier, amidst much faster-flowing ice (300-1300 m/year). Additionally, a number of anomalously drawn-down englacial radar reflections are observed in multiple aerogeophysical surveys with the McCORDs (Multichannel Coherent Radar Depth Sounder) Instrument upstream of this ice velocity anomaly. 

The potential source of this velocity anomaly is hypothesized to be either anomalous geothermal flux or high frictional heat upstream, coupled to a thinning of the ice column as it nears the grounding line. These factors, taken together, imply a scenario where the warmer ice at the base of the ice column melts away while colder ice enters from above at the accumulation rate along the flowline. Upstream, with the ice column's relatively high thickness (~1000m), the basal ice experiences sufficient pressure to induce significant down draw of layers from substantial melting that is consistent with basal friction and/or a source of anomalous geothermal flux; the result is significant thermal advection of the much colder surface accumulation deep into the ice column. Downstream, where the ice thins, the  reduced pressure results in freezing of the anomalously cold ice to the bed, leading to the observed velocity anomaly.The testing of this hypothesis requires reconciling of the vertical velocity profile necessary to produce the down draw with either expected frictional melt or anomalous geothermal flux along the flowline (given the accumulation gradient). We present here this coupled thermal and kinematic modeling of Haynes Glacier from the site of the down draw to the sticky spot near the grounding line. With our models of temperature variations and ice flow characteristics within the Haynes Glacier system, we can further refine our understanding of the importance of heterogeneous geothermal flux for cryosphere evolution  - which may prove to be vitally important to fully understand fast-flowing and vulnerable ice streams in the Amundsen Embayment of West Antarctica. This, in turn, may have further implications for the study of heterogeneous heat flux and volcanic activity within the broader context of West Antarctica.