Update 29 March 2019 (by Ralf Greve):

Converted to NetCDF classic format by
  nccopy -k classic dsmb_xxe3413_ISMIP6_v2.nc \
                    dsmb_xx_ISMIP6_v2_EPSG3413.nc
for resolutions of xx=20, 10 and 05 km.

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Files final version from 1 February 2016: Version 2
Description last updated
24 September 2018, Heiko Goelzer (h.goelzer@uu.nl)

*** Important note ***
For consistency with future ISMIP6 intercomparison exercises and some
observational data sets, we have re-gridded the forcing data to a new
grid following the EPSG:3413 specifications, which differs from the
grid originally used to distribute the forcing data.

The files in this directory contain the surface mass balance (SMB)
anomaly that needs to be used for initMIP-Greenland. The units are
(meter ice equivalent/year) with an assumed density of 910 kg/m^3 and
31556926 s/yr. This anomaly is schematic and should not be considered
as a realistic projection.

The core experiment duration is 100 years.

The SMB anomaly is to be implemented as a time dependent function,
that takes the form of a linear function which increases stepwise
every full year (it is therefore independent of the time step in the
model):
   SMB(t) = SMB_initialization + SMB_anomaly * (floor (t) / 40);
            for t in year from 0 to 40
   SMB(t) = SMB_initialization + SMB_anomaly * 1.0;
            for t > 40 years
where SMB_anomaly is the anomaly provided by ISMIP6 and
SMB_initialisation is the SMB used for the initialisation.

A control run of the same time duration needs to also be
submitted. The models are run forward without any anomaly forcing,
such that whatever surface mass balance (SMB_initialisation) was used
in the initialisation technique would continue unchanged:
SMB(t) = SMB_initialisation for all t.

Note that no adjustment of SMB due to geometric changes in the
experiments is allowed (i.e. no elevation – SMB feedback!), to ensure
that all models will prescribe the same anomaly.

Modelling groups should use the 1 km version of the SMB_anomaly to
conservatively interpolate to their model native grid. Files of lower
resolution (5 km, 10 km, and 20 km) are provided for groups using a
native grid based on EPSG:3413. Please see the wiki for suggestion on
how to conservatively interpolate.

SMB anomaly files on EPSG:3413:
1km: dsmb_01e3413_ISMIP6_v2.nc
5km: dsmb_05e3413_ISMIP6_v2.nc
10km: dsmb_10e3413_ISMIP6_v2.nc
20km: dsmb_20e3413_ISMIP6_v2.nc
...
