Downscaled surface mass balance in Antarctica: impacts of subsurface processes and large-scale atmospheric circulation
Nicolaj Hansen,Peter L. Langen,Fredrik Boberg,René Forsberg,Sebastian B. Simonsen,Peter Thejll,Baptiste Vandecrux,Ruth Mottram +7 more
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In this paper, the authors examine factors that influence Antarctic surface mass balance and attempt to reconcile the outcome with estimates for total mass balance determined from the GRACE satellites, by having the regional climate model HIRHAM5 forcing two versions of an offline subsurface model to estimate Antarctic ice sheet (AIS) from 1980 to 2017.Abstract:
. Antarctic surface mass balance (SMB) is largely determined by precipitation over the continent and subject to regional climate variability related to the Southern Annular Mode (SAM) and other climatic drivers at the large scale. Locally however, firn and snowpack processes are important in determining SMB and the total mass balance of Antarctica and global sea level. Here, we examine factors that influence Antarctic SMB and attempt to reconcile the outcome with estimates for total mass balance determined from the GRACE satellites. This is done by having the regional climate model HIRHAM5 forcing two versions of an offline subsurface model, to estimate Antarctic ice sheet (AIS) SMB from 1980 to 2017. The Lagrangian subsurface model estimates Antarctic SMB of 2473.5±114.4 Gt yr −1 , while the Eulerian subsurface model variant results in slightly higher modelled SMB of 2564.8±113.7 Gt yr −1 . The majority of this difference in modelled SMB is due to melt and refreezing over ice shelves and demonstrates the importance of firn modelling in areas with substantial melt. Both the Eulerian and the Lagrangian SMB estimates are within uncertainty ranges of each other and within the range of other SMB studies. However, the Lagrangian version has better statistics when modelling the densities. Further, analysis of the relationship between SMB in individual drainage basins and the SAM is carried out using a bootstrapping approach. This shows a robust relationship between SAM and SMB in half of the basins (13 out of 27). In general, when SAM is positive there is a lower SMB over the plateau and a higher SMB on the westerly side of the Antarctic Peninsula, and vice versa when the SAM is negative. Finally, we compare the modelled SMB to GRACE data by subtracting the solid ice discharge, and we find that there is a good agreement in East Antarctica but large disagreements over the Antarctic Peninsula. There is a large difference between published estimates of discharge that make it challenging to use mass reconciliation in evaluating SMB models on the basin scale.read more
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Interpretation of recent Southern Hemisphere climate change
TL;DR: In this paper, it is argued that the largest and most significant tropospheric trends can be traced to recent trends in the lower stratospheric polar vortex, which are due largely to photochemical ozone losses, and the trend toward stronger circumpolar flow has contributed substantially to the observed warming over the Antarctic Peninsula and Patagonia and to the cooling over eastern Antarctica and the Antarctic plateau.
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Variability in Antarctic surface climatology across regional climate models and reanalysis datasets
TL;DR: In this article , the authors examined variability in snowfall, near-surface air temperature and melt across products from the Met Office Unified Model (MetUM), Regional Atmospheric Climate Model (RACMO) and Modèle Atmosphérique Régional (MAR) RCMs, as well as the ERA-Interim and ERA5 reanalysis datasets.
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Brief communication: Impact of common ice mask in surface mass balance estimates over the Antarctic ice sheet
Ruth Mottram,Niels Souverijns,Sebastian B. Simonsen,Nicolaj Hansen,Farhanahani Mahmud,ewennactxp +5 more
TL;DR: In this article , the authors proposed a common ice mask protocol to harmonize regional climate models and found that the common mask in areas outside coastal and high-precipitation regions can change integrated SMB by between 40.5 and 140.6 Gt yr−1 (1.8 % to 6.0 % of ensemble mean SMB).
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A closed-form equation for predicting the hydraulic conductivity of unsaturated soils
van Genuchten,M. Th. +1 more
TL;DR: Van Genuchten et al. as mentioned in this paper proposed a closed-form analytical expression for predicting the hydraulic conductivity of unsaturated soils based on the Mualem theory, which can be used to predict the unsaturated hydraulic flow and mass transport in unsaturated zone.
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The ERA-Interim reanalysis: configuration and performance of the data assimilation system
Dick Dee,S. Uppala,Adrian Simmons,Paul Berrisford,Paul Poli,Shinya Kobayashi,Ulf Andrae,Magdalena Balmaseda,Gianpaolo Balsamo,Peter Bauer,Peter Bechtold,Anton Beljaars,L. van de Berg,Jean Bidlot,Niels Bormann,C. Delsol,Rossana Dragani,Manuel Fuentes,Alan J. Geer,Leopold Haimberger,Sean Healy,Hans Hersbach,Elías Hólm,Lars Isaksen,P. Kallberg,Martin Köhler,Marco Matricardi,A. P. McNally,B. M. Monge-Sanz,Jean-Jacques Morcrette,B.-K. Park,Carole Peubey,P. de Rosnay,Christina Tavolato,Jean-Noël Thépaut,Frederic Vitart +35 more
TL;DR: ERA-Interim as discussed by the authors is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), which will extend back to the early part of the twentieth century.
Journal ArticleDOI
Interpretation of recent Southern Hemisphere climate change
TL;DR: In this article, it is argued that the largest and most significant tropospheric trends can be traced to recent trends in the lower stratospheric polar vortex, which are due largely to photochemical ozone losses, and the trend toward stronger circumpolar flow has contributed substantially to the observed warming over the Antarctic Peninsula and Patagonia and to the cooling over eastern Antarctica and the Antarctic plateau.
Journal ArticleDOI
Bedmap2: improved ice bed, surface and thickness datasets for Antarctica
Peter T. Fretwell,Hamish D. Pritchard,David G. Vaughan,Jonathan L. Bamber,Nicholas E. Barrand,Ruth Bell,Cesidio Bianchi,Robert Bingham,Donald D. Blankenship,Gino Casassa,Ginny A. Catania,Denis Callens,Howard Conway,Alison J. Cook,Hugh F. J. Corr,Detlef Damaske,Volkmar Damm,Fausto Ferraccioli,René Forsberg,Shuji Fujita,Y. Gim,Prasad Gogineni,J. A. Griggs,Richard C. A. Hindmarsh,Per Holmlund,John W. Holt,Robert W. Jacobel,Adrian Jenkins,Wilfried Jokat,Tom A. Jordan,Edward C. King,Jack Kohler,William B. Krabill,M. Riger-Kusk,Kirsty Langley,German Leitchenkov,Carl Leuschen,Bruce P. Luyendyk,Kenichi Matsuoka,Jeremie Mouginot,F. O. Nitsche,Yoshifumi Nogi,Ole Anders Nøst,S. V. Popov,Eric Rignot,David M. Rippin,Andrés Rivera,Jason L. Roberts,Neil Ross,Martin J. Siegert,Andrew Smith,Daniel Steinhage,Michael Studinger,Bo Sun,B. K. Tinto,Brian C. Welch,Douglas S. Wilson,Duncan A. Young,Cui Xiangbin,Achille Zirizzotti +59 more
TL;DR: Bedmap2 as discussed by the authors is a suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60° S. In particular, the Bedmap2 ice thickness grid is made from 25 million measurements, over two orders of magnitude more than were used in Bedmap1.