Ice-sheet Temperature Around Subglacial Lake Vostok Constrained by New Flowband Modeling
Abstract
Previous attenuation modeling has suggested that the englacial depth averaged attenuation rate of radio-wave energy changes significantly as ice flows across Subglacial Lake Vostok (SLV) in East Antarctica. The englacial attenuation rate is dependent predominately on ice temperature, implying that the attenuation of the radar signal can be used to constrain the basal ice temperature over SLV, and this can be used to estimate the basal melt rate (or accretion rate). We use a 1-D model to calculate ice-temperature profiles over SLV to relate the basal melt rate to the depth averaged attenuation rate. Our 1-D model can be tuned to match the measured temperature profile at the Vostok ice-core site, but this requires a higher surface accumulation rate than what has been measured. In order to address this discrepancy and reliably be able to apply the 1-D model across the entirety of the lake we use a flowband (2.5-D) shallow-ice approximation model coupled to a thermodynamic model to map the discrepancy across SLV. In this model we need to estimate the length of the transition from grounded to floating ice at SLV and we use output from an idealized full-stress model (Elmer/Ice). The flowband model is matched to the measured temperature profile at the ice-core site by tuning the geothermal heat flux, and then applied the entirety of the lake. Our new flowband modeling will determine where the temperature field is not significantly affected by the basal melting or accretion at the ice water interface, most likely around the border of SLV. This work will help to constrain the basal melt and accretion rates over SLV, an important factor in understanding the flux of biologically available oxidants.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.C21B0688K
- Keywords:
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- 0720 Glaciers;
- CRYOSPHEREDE: 0726 Ice sheets;
- CRYOSPHEREDE: 0774 Dynamics;
- CRYOSPHEREDE: 0798 Modeling;
- CRYOSPHERE