Surface mass balance contributions to acceleration of Antarctic ice mass loss during 2003–2013

Abstract

Recent observations from satellite gravimetry (the Gravity Recovery and Climate Experiment (GRACE) mission) suggest an acceleration of ice mass loss from the Antarctic Ice Sheet (AIS). The contribution of surface mass balance changes (due to variable precipitation) is compared with GRACE‐derived mass loss acceleration by assessing the estimated contribution of snow mass from meteorological reanalysis data. We find that over much of the continent, the acceleration can be explained by precipitation anomalies. However, on the Antarctic Peninsula and other parts of West Antarctica, mass changes are not explained by precipitation and are likely associated with ice discharge rate increases. The total apparent GRACE acceleration over all of the AIS between 2003 and 2013 is −13.6 ± 7.2 Gt/yr2. Of this total, we find that the surface mass balance component is −8.2 ± 2.0 Gt/yr2. However, the GRACE estimate appears to contain errors arising from the atmospheric pressure fields used to remove air mass effects. The estimated acceleration error from this effect is about 9.8 ± 5.8 Gt/yr2. Correcting for this yields an ice discharge acceleration of −15.1 ± 6.5 Gt/yr2.

A global assessment of accelerations in surface mass transport

“…The sum over the globe is nearly zero when atmospheric mass is included. Nonatmospheric accelerations are also shown after atmospheric mass is removed using European Centre for Medium‐Range Weather Forecasts ERA‐Interim model and thus subject to possible errors in the model [e.g., Seo et al ., ]. The a posteriori chi‐square calibrated uncertainties include the effects of irregular variations in addition to those of data errors and thus should also serve as indications of such irregular and interannual variations.…”

“…Only since the launch of the Gravity Recovery and Climate Experiment (GRACE) mission in 2002 has this phenomenon been monitored globally with unprecedented resolution and accuracy [ Tapley et al ., ]. Greenland and West Antarctica have lost significant mass at accelerated rates recently [e.g., Chen et al ., ; Velicogna , ; Rignot et al ., ; Luthcke et al ., ; Seo et al ., ]. These accelerated mass losses have sometimes been translated to an equivalent sea level rise and projected to the future for a 56 cm sea level rise by 2100 [ Rignot et al ., ].…”

Mass balance of the Antarctic Ice Sheet from 1992 to 2017

“…We distinguish the later methods, referring to them as 'post-spherical-harmonic mascons' . Eleven contributions are derived from monthly spherical-harmonic solutions of the global gravity field using different approaches 55,56,[61][62][63][64][65][66] , which can be loosely classified as (i) region-integration approaches 55,65,66 , (ii) post-spherical-harmonic mascon approaches 56,[61][62][63] , (iii) forward-modelling approaches 62,64 , which essentially involve modelling of mass change with iterative comparison to the GRACE-derived signal, and (iv) approaches that use Slepian functions 67 . One final estimate 68 made use of satellite altimetry data; although this estimate was excluded from our gravity ensemble average because it is a hybrid solution, it is presented alongside the gravimetry-only results for comparison.…”

Which Extratropical Cyclones Contribute Most to the Transport of Moisture in the Southern Hemisphere?

“…The Antarctic ice sheet is the largest potential source of future sea level rise due to its large mass (Schoen et al, 2015). Variability in Antarctic ice mass is determined by the balance between precipitation accumulation over the continent and mass loss due to melting, sublimation, and ice calving (Bromwich, 1990;Davis et al, 2005;Roberts et al, 2015;Seo et al, 2015). Since a large fraction of the precipitation in Antarctica is associated with ETCs, changes in ETC number and moisture transport that result in a changed distribution of precipitation will be important for future Antarctic ice mass (Altnau et al, 2015;Noone et al, 1999;Papritz et al, 2014).…”