Mapping Basal Melt Under the Shackleton Ice Shelf, East Antarctica, From CryoSat-2 Radar Altimetry

Ice shelvesbuttress the fast-flowing glaciers draining ice sheets, so changes in the ice shelves may alter the buttressing effect and the discharge of grounded ice, therefore influencing sea level. Basal melting of the ice shelves would reduce their ability to restrain the discharge of grounded ice into the ocean. However, estimating the basal melt rate is challenging due to the large uncertainty in the calculation. In this study, we use a Lagrangian framework to improve the basal melt rate derivation and apply the method to the Shackleton ice shelf as a case study. We use the CryoSat-2 data to characterize the spatial distribution patterns of ice shelf surface elevation changes between 2010 and 2018. Combining these results with the ice surface velocity and output from the regional climate model, we obtain a map of the basal melt rate and calculate the total and average basal mass balance. The total basal meltwater production for the Shackleton ice shelf is 54.6 ± 7.2 Gt/yr. The highest melt rates, which exceed 50 m/yr, are found close to the grounding line and the main trunk of Denman glacier. Based on the analysis, we show that the Lagrangian method can provide more spatially coherent patterns of ice shelf surface elevation changes and reduce the uncertainty in basal melt rate calculation.

[1]  Lei Zheng,et al.  Comparisons of snowmelt detected by microwave sensors on the Shackleton Ice Shelf, East Antarctica , 2020, International Journal of Remote Sensing.

[2]  P. Heimbach,et al.  Satellite-derived submarine melt rates and mass balance (2011–2015) for Greenland's largest remaining ice tongues , 2017 .

[3]  Donald D. Blankenship,et al.  Antarctic Mapping Tools for Matlab , 2017, Comput. Geosci..

[4]  Fengming Hui,et al.  Ocean-driven thinning enhances iceberg calving and retreat of Antarctic ice shelves , 2015, Proceedings of the National Academy of Sciences.

[5]  A. Shepherd,et al.  Assessment of CryoSat-2 interferometric and non-interferometric SAR altimetry over ice sheets , 2017, Advances in Space Research.

[6]  Stephen D. McPhail,et al.  Observations beneath Pine Island Glacier in West Antarctica and implications for its retreat , 2010 .

[7]  T. Neumann,et al.  Assessment of ICESat‐2 Ice Sheet Surface Heights, Based on Comparisons Over the Interior of the Antarctic Ice Sheet , 2019, Geophysical Research Letters.

[8]  G. Williams,et al.  Circulation of modified Circumpolar Deep Water and basal melt beneath the Amery Ice Shelf, East Antarctica , 2015 .

[9]  M. R. van den Broeke,et al.  Calving fluxes and basal melt rates of Antarctic ice shelves , 2013, Nature.

[10]  Rolf König,et al.  EIGEN-6C4 - The latest combined global gravity field model including GOCE data up to degree and order 1949 of GFZ Potsdam and GRGS Toulouse , 2011 .

[11]  Angelika Humbert,et al.  Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2 , 2014 .

[12]  はやのん,et al.  What are the polar regions , 2008 .

[13]  A. Muir,et al.  CryoSat-2 swath interferometric altimetry for mapping ice elevation and elevation change , 2017, Advances in Space Research.

[14]  Fernando S. Paolo,et al.  Volume loss from Antarctic ice shelves is accelerating , 2015, Science.

[15]  Frank Kauker,et al.  Twenty-first-century warming of a large Antarctic ice-shelf cavity by a redirected coastal current , 2012, Nature.

[16]  B. Scheuchl,et al.  Ice Flow of the Antarctic Ice Sheet , 2011, Science.

[17]  R. Armstrong,et al.  The Physics of Glaciers , 1981 .

[18]  S. Tulaczyk,et al.  A decade of West Antarctic subglacial lake interactions from combined ICESat and CryoSat‐2 altimetry , 2014 .

[19]  Maik Thomas,et al.  Melting and freezing under Antarctic ice shelves from a combination of ice-sheet modelling and observations , 2017, Journal of Glaciology.

[20]  D. Menemenlis,et al.  Ice shelf basal melt rates around Antarctica from simulations and observations , 2016 .

[21]  A. Leeson,et al.  Distribution and seasonal evolution of supraglacial lakes on Shackleton Ice Shelf, East Antarctica , 2020 .

[22]  Eric Rignot,et al.  Basal terraces on melting ice shelves , 2014 .

[23]  A. Passerini,et al.  Refined broad-scale sub-glacial morphology of Aurora Subglacial Basin, East Antarctica derived by an ice-dynamics-based interpolation scheme , 2011 .

[24]  Jonathan L. Bamber,et al.  Antarctic ice shelf thickness from CryoSat‐2 radar altimetry , 2015 .

[25]  Won Sang Lee,et al.  Deep glacial troughs and stabilizing ridges unveiled beneath the margins of the Antarctic ice sheet , 2019, Nature Geoscience.

[26]  Duncan J. Wingham,et al.  Increased ice losses from Antarctica detected by CryoSat‐2 , 2014 .

[27]  S. Jacobs,et al.  Rapid Bottom Melting Widespread near Antarctic Ice Sheet Grounding Lines , 2002, Science.

[28]  Luis A. Hückstädt,et al.  Oceanic controls on the mass balance of Wilkins Ice Shelf, Antarctica , 2012 .

[29]  M. R. van den Broeke,et al.  An improved semi-empirical model for the densification of Antarctic firn , 2011 .

[30]  A. Jenkins,et al.  Strong Sensitivity of Pine Island Ice-Shelf Melting to Climatic Variability , 2014, Science.

[31]  B. Smith,et al.  GPS-derived estimates of surface mass balance and ocean-induced basal melt for Pine Island Glacier ice shelf, Antarctica , 2017 .

[32]  B. Scheuchl,et al.  Ice-Shelf Melting Around Antarctica , 2013, Science.

[33]  R. Bell,et al.  Antarctic surface hydrology and impacts on ice-sheet mass balance , 2018, Nature Climate Change.

[34]  David M. Holland,et al.  Novel monitoring of Antarctic ice shelf basal melting using a fiber‐optic distributed temperature sensing mooring , 2014 .

[35]  B. Smith,et al.  Ice shelf basal melt rates from a high-resolution digital elevation model (DEM) record for Pine Island Glacier, Antarctica , 2019, The Cryosphere.

[36]  A. Vieli,et al.  Rapid, climate-driven changes in outlet glaciers on the Pacific coast of East Antarctica , 2013, Nature.

[37]  Susheel Adusumilli,et al.  Variable Basal Melt Rates of Antarctic Peninsula Ice Shelves, 1994–2016 , 2018 .

[38]  Tommaso Parrinello,et al.  A new digital elevation model of Antarctica derived from CryoSat-2 altimetry , 2017 .

[39]  F. Pattyn,et al.  Detecting high spatial variability of ice shelf basal mass balance, Roi Baudouin Ice Shelf, Antarctica , 2017 .

[40]  Lei Zheng,et al.  Antarctic Snowmelt Detected by Diurnal Variations of AMSR-E Brightness Temperature , 2016, Remote. Sens..

[41]  Fang Wang,et al.  Accuracy and Performance of CryoSat-2 SARIn Mode Data Over Antarctica , 2015, IEEE Geoscience and Remote Sensing Letters.

[42]  Richard Coleman,et al.  A new tide model for the Antarctic ice shelves and seas , 2002, Annals of Glaciology.

[43]  Bernd Scheuchl,et al.  Mapping of Ice Motion in Antarctica Using Synthetic-Aperture Radar Data , 2012, Remote. Sens..

[44]  A. Shepherd,et al.  Tide model accuracy in the Amundsen Sea, Antarctica, from radar interferometry observations of ice shelf motion , 2011 .

[45]  B. Scheuchl,et al.  Rapid submarine ice melting in the grounding zones of ice shelves in West Antarctica , 2016, Nature Communications.

[46]  Eric Rignot,et al.  Global sea-level budget 1993–present , 2018, Earth System Science Data.

[47]  H. Fricker,et al.  Basal mass budget of Ross and Filchner‐Ronne ice shelves, Antarctica, derived from Lagrangian analysis of ICESat altimetry , 2014 .

[48]  B. Scheuchl,et al.  Grounding Line Retreat of Denman Glacier, East Antarctica, Measured With COSMO‐SkyMed Radar Interferometry Data , 2020, Geophysical Research Letters.

[49]  David J. Harding,et al.  The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2): Science requirements, concept, and implementation , 2017 .

[50]  B. Scheuchl,et al.  Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica , 2019, Science Advances.

[51]  P. Skvarca,et al.  Larsen Ice Shelf Has Progressively Thinned , 2003, Science.

[52]  K. Kusahara,et al.  Modeling Antarctic ice shelf responses to future climate changes and impacts on the ocean , 2013 .

[53]  Ian Joughin,et al.  Pine Island glacier ice shelf melt distributed at kilometre scales , 2013 .

[54]  L. Phalippou,et al.  CryoSat: A mission to determine the fluctuations in Earth’s land and marine ice fields ☆ , 2006 .

[55]  S. Lhermitte,et al.  Modelling the climate and surface mass balance of polar ice sheets using RACMO2 – Part 2: Antarctica (1979–2016) , 2017 .

[56]  T. Parrinello,et al.  CryoSat: ESA’s ice mission – Eight years in space , 2018, Advances in Space Research.

[57]  D. Vaughan,et al.  Antarctic ice-sheet loss driven by basal melting of ice shelves , 2012, Nature.

[58]  M. R. van den Broeke,et al.  Present and future variations in Antarctic firn air content , 2014 .

[59]  R. Gerdes,et al.  Ocean circulation beneath Filchner‐Ronne Ice Shelf from three‐dimensional model results , 1999 .

[60]  Gwyn Griffiths,et al.  Measurements beneath an Antarctic ice shelf using an autonomous underwater vehicle , 2006 .

[61]  R. Bindschadler,et al.  Channelized Ice Melting in the Ocean Boundary Layer Beneath Pine Island Glacier, Antarctica , 2013, Science.

[62]  Kate Snow,et al.  Channelized Melting Drives Thinning Under a Rapidly Melting Antarctic Ice Shelf , 2017 .