2 research outputs found
The future sea-level rise contribution of Greenland’s glaciers and ice caps
We calculate the future sea-level rise contribution from the surface mass balance of all of Greenland's glaciers and ice caps (GICs, ~90 000 km2) using a simplified energy balance model which is driven by three future climate scenarios from the regional climate models HIRHAM5, RACMO2 and MAR. Glacier extent and surface elevation are modified during the mass balance model runs according to a glacier retreat parameterization. Mass balance and glacier surface change are both calculated on a 250 m resolution digital elevation model yielding a high level of detail and ensuring that important feedback mechanisms are considered. The mass loss of all GICs by 2098 is calculated to be 2016 ± 129 Gt (HIRHAM5 forcing), 2584 ± 109 Gt (RACMO2) and 3907 ± 108 Gt (MAR). This corresponds to a total contribution to sea-level rise of 5.8 ± 0.4, 7.4 ± 0.3 and 11.2 ± 0.3 mm, respectively. Sensitivity experiments suggest that mass loss could be higher by 20–30% if a strong lowering of the surface albedo were to take place in the future. It is shown that the sea-level rise contribution from the north-easterly regions of Greenland is reduced by increasing precipitation while mass loss in the southern half of Greenland is dominated by steadily decreasing summer mass balances. In addition we observe glaciers in the north-eastern part of Greenland changing their characteristics towards greater activity and mass turnover
Seasonal velocities of eight major marine-terminating outlet glaciers of the Greenland ice sheet from continuous in situ GPS instruments
We present 17 velocity records derived from in situ stand-alone
single-frequency Global Positioning System (GPS) receivers placed on eight
marine-terminating ice sheet outlet glaciers in South, West and North
Greenland, covering varying parts of the period summer 2009 to summer 2012.
Common to all the observed glacier velocity records is a pronounced seasonal
variation, with an early melt season maximum generally followed by a rapid
mid-melt season deceleration. The GPS-derived velocities are compared to
velocities derived from radar satellite imagery over six of the glaciers to
illustrate the potential of the GPS data for validation purposes. Three
different velocity map products are evaluated, based on ALOS/PALSAR data,
TerraSAR-X/Tandem-X data and an aggregate winter TerraSAR-X data set. The
velocity maps derived from TerraSAR-X/Tandem-X data have a mean difference
of 1.5% compared to the mean GPS velocity over the corresponding period,
while velocity maps derived from ALOS/PALSAR data have a mean difference of
9.7%. The velocity maps derived from the aggregate winter TerraSAR-X data
set have a mean difference of 9.5% to the corresponding GPS velocities.
The data are available from the GEUS repository at doi:10.5280/GEUS000001