Abstract
Antarctic basal water storage variations (BWSV) refer to the mass variations of liquid water beneath Antarctic ice sheet. Identifying these variations is critical to understand the behaviour of ice sheet, yet it is rarely accessible to direct observation. We presented a layered gravity density forward/inversion method for estimating Antarctic BWSV from multi- source satellite observation data, and relevant models. Results reveal spatial variability of BWSV with the mean rate of 43 ± 13 Gt/yr during 2003–2009, which is 21 Gt/yr lower than basal melting rate. This indicates that the basal meltwater beneath Antarctic ice sheet is decreasing with the rate of −21 ± 13 Gt/yr, accounting for 28 % of the mass balance rate (−76 Gt/yr, Shepherd et al. (2018)), and the basal water migrations between basal drainage systems and oceans is non-ignorable in estimating basal mass balance of Antarctic ice sheet. Similar spatial distribution of basal water increases regions and locations of active subglacial lakes indicates that basal water storage in most active subglacial lakes is increasing. In most region of Antarctic ice sheet except Amundsen Sea coast region, the comparison of spatial BWSV and ice velocity displays a positive correlation between considerable basal water increases and rapid/accelerated ice flows, which indicates that BWSV appear to have an important effect on ice flows. Accordingly, we infer that further enhanced flow velocities are expected if basal water continues to increase in these regions.
Highlights
Antarctic basal water is widely generated by geothermal heating, basal pressure melting and frictional heating
The associated standard deviations (STD) (Figure 10d-10f) shows consistent spatial distributions: the largest STD (≥15 mm/yr) are in APIS and WAIS, which mainly comes from the STD of Gravity Recovery and Climate Experiment (GRACE), ICESat (25%, mainly from inter-campaign biases (ICB)), firn densification model (FDM) (20%) and GPS (20%); the medium STD (10-15 mm/yr) are in the marginal region of EAIS, mainly coming from GRACE (40%), ICESat (30%) and FDM (20%); the low STD (
We presented a layered gravity density forward/inversion method for estimating basal mass balance (BMB) and basal water storage variations (BWSV) rates beneath Antarctic ice sheet (AIS) during 2003-2009, by a combination of multi-source satellite observation data including satellite gravity, altimetry and GPS data, and relevant models including firn densification model 385 (FDM), glacial isostatic adjustment and basal melting rate
Summary
Antarctic basal water is widely generated by geothermal heating, basal pressure melting and frictional heating. The basal liquid water converge on subglacial lakes or spread over ice-bed interface, and connected to each other (Wingham et al, 2006;Fricker et al, 2016), which forms basal drainage systems with complex basal water migrations (Pattyn, 2008;Carter et al, 2015). 25 Temporal mass variations in Antarctic basal liquid water storage are called basal water storage variations (BWSV), it influences basal effective pressure and trigger changing ice sheet velocities (Bell and Robin, 2008;Fricker et al, 2007;Alley, 1992). BWSV are mainly controlled by basal melting rate and basal water migrations.
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