Antarctica

5-day forecast of the 2025-2026 Antarctic ice sheet SMB
simulated by MARv3.14 forced by GFS

Fig 0: Time series of the anomaly of cumulated Antarctic ice sheet (AIS) Surface Mass Balance (SMB) in GT simulated by the regional climate model MAR (version 3.14, run at a resolution of 27.5km) forced by the ERA5 reanalysis (1979- 15 Dec 2025) and by the Global Forecast System (GFS) model (Dec 2025-the today's date +5 days in forecast mode). The gray shading area represents the 1981-2010 standard deviation around the 1981-2010 average. The ERA5 based climatology has been built by Christoph Kittel using the same MAR version and set-up. Only the lateral boundary forcing (GFS) is different. 

Be careful that the time series is not homogeneous as we compare here MAR-GFS over 2025-2026 to the climatology MAR-ERA5.

Fig 1: a) Time series of the cumulated Antarctic ice sheet (AIS) Surface Mass Balance (SMB) in GT simulated by the regional climate model MAR (version 3.14, run at a resolution of 27.5km) forced by the ERA5 reanalysis (1979-Dec 2025) and by the Global Forecast System (GFS) model (Dec 2025-the today's date +5 days in forecast mode). The 1981-2010 mean simulated by MARv3.14 forced by ERA5 is also plotted in black. The 0-24h forecast of each day from the GFS run of 00hTU has been used to build the time series from the end of ERA5 (Nov 2025) to now. Finally, the gray shading area represents the standard deviation around the 1981-2010 average (in black). Same as b) but for the cumulated meltwater and runoff in dash (most of the meltwater is retained by the snowpack and does not runoff to the ocean) c) Same as a) but for the daily SMB in GT/day.  The absolute maximum/minimum SMB rate of each day is plotted in blue. d) Daily mean AIS near-surface temperature (TAS) simulated by MAR. The absolute maximum temperature of each day is plotted in blue. e) Time series of the Antarctica oscillation index from Climate Prediction Center (CPC).

Fig 2a: Left) Cumulated SMB (in mm) from the 1 Mar 2025 to the today's date. Right) Same as Left) but in respect to the 1981-2010 ERA5 forced average from the 1 Mar to the today's date. The anomalies lower than the 1981-2010 interannual variability are hatched.

Fig 2b: Same as Fig 2a but for snowfall.

Fig 2c: Same as Fig 2a but for meltwater. Be carefull that most of this meltwater is retained by the snowpack and does not runoff to the ocean.

Fig 3: Time series of a) the daily mean AIS production of meltwater (in GT/day), b) daily mean AIS incomming long/shortwave radiation (in W/m²)), c) daily mean AIS surface albedo simulated by MARv3.12.

Fig 4: Left) Number of melt days ( (i.e. when the daily meltwater production > 1 mmWE/day) from the 1 Mar 2025 to the today's date. Right) Same as Left) but in respect to the 1981-2010 average from 1 Nov 2025.

Fig 5: Melt extent as derived simulated by MARv3.12 forced by ERA5 and forecasted forced by GFS. Daily meltwater production > 1 mmWE/day is used here as melt threshold. As the ice sheet mask, resolution and melt threshold is not the same than those ones used for MAR, the comparison with this satellite based product is just given as information...  

Fig 6: Left) Near-surface temperature anomaly (in °C) of the today's date in respect to the 1981-2010 average. Right) Same as Left) but from 1 Nov 2025.

(c) Xavier Fettweis, University of Liège (ULiège), Belgium

Interesting link:
- Current status of surface melt in Antarctica from Ghislain Picard.
- MARv3.14 daily outputs on 1979-2026.