The Laboratory » Team » Dr. Xavier FETTWEIS » The 2018 melt season over Greenland as simulated by MARv3.9

The 2018 melt season over Greenland as simulated by MARv3.9

7-day forecast of 
the 2018 Greenland ice sheet SMB
simulated by MARv3.9 forced by GFS

 (automatic updated every day around 8h TU)

Fig 1: a) Time series of the cumulated Greenland ice sheet (GrIS) Surface Mass Balance (SMB) in GT simulated by the regional climate model MAR (version 3.9.3, run at a resolution of 15km) forced by the ERA-Interim reanalysis (1979-Mar 2018) and by the Global Forecast System (GFS) model (Apr 2018-the today's date +7 days in forecast mode) since 1 Sep 2011 (in green), and 1 Sep 2018 (in red). The 1981-2010 mean simulated by MARv3.9 forced by ERA-Interim 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 ERA-Interim (March 2018) to now. b) Same as a) but for the daily SMB in GT/day.  The absolute maximum/minimum SMB rate of each day is plotted in blue. c) Daily mean GrIS near-surface temperature (TAS) simulated by MAR. The absolute maximum temperature of each day is plotted in blue. d) Time series of the North Atlantic Oscillation (NAO) index from Climate Prediction Center (CPC).

 


Fig 2a: Left) Cumulated SMB (in mm) from the 1 Sep 2017 to the today's date. Right) Same as Left) but in respect to the 1981-2010 ERA-Interim forced average from the 1 Sep 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 run-off.

 


Fig 3: Time series of a) the daily mean GrIS Run-off (in GT/day), b) production of meltwater (in GT/day), c) daily mean GrIS incomming long/shortwave radiation (in W/m²)), d) bare ice extent (i.e. area where the surface density is > 900 kg/m^3 in % of the ice sheet surface) and e) daily mean GrIS surface albedo simulated by MARv3.9 forced by ERA-Interim (1981-2018).

 
 
 
Fig 4: Left) Number of melt days ( (i.e. when the daily meltwater production > 5 mmWE/day) from the 1 May 2018 to the today's date. Right) Same as Left) but in respect to the 1981-2010 average from 1 May to 31 Aug.
 
 
Fig 5: Left) Melt extent as derived from satellite data (Credit: NSIDC/Thomas Mote). Right) Same as a) but as simulated by MARv3.9 forced by ERA-Interim and forecasted forced by GFS. Daily meltwater production > 5 mmWE/day is used here as melt threshold in MARv3.9. This melt threshold has been chosen independently of the NSIDC data and mainly explains why both estimations do not generally compare.
 
 
 
Fig 6: Greenland bloking index (GBI) from NCEP-NCARv1 in red and from the Global Forecast System (GFS) based forcasting in dashed red. According to Hanna et al. (2013), the GBI is defined as the 500hPa geopotential height (Z500) area averaged over 60-80°N, 280-340°E.  
 
 
 
Fig 7: Idem as Fig. 6 but for 700hPa temperature (T700) averaged over 60-80°N, 280-340°E.  
 
 
 
Fig 8: Left) Anomaly of surface albedo in respect to the 1981-2010 average over the same day (today's date). Righ) Anomaly of the JJA mean surface albedo in respect to the 1981-2010 average from 1 May to the today's date. 
 
 
Fig 9: Same as Fig. 8 but for the near-surface temperature (~2m) as simulated by MARv3.9 forced by ERA-Interim. 
 
 
Fig 10: Same as Fig. 9 but for the incoming shortwave radiation (in W/m²) as simulated by MARv3.9 forced by ERA-Interim. 
 
 
Interesting links:
 

(c) Xavier FettweisUniversity of Liège (ULiège), Belgium

 

These forecasts are only provided for information in the aim of following the 2018 melting season over Greenland in real time; ULiège can not be held responsible for any use beyond this scope.