Jökull - 01.01.2016, Page 3

The subglacial topography of Drangajökull ice cap, NW-Iceland
Figure 1. Location of the study area. The contour map (50 m elevation interval) shows Drangajökull ice cap
and vicinity as mapped with airborne laser scanning (Lidar) 20 July 2011 (Jóhannesson et al., 2013). – Hæðar-
línukort (50 m milli hæðarlína) af Drangajökli og næsta nágrenni skv. mælingum sem gerðar voru með leysi-
skanna úr flugvél, 20. júlí, 2011 (Tómas Jóhannesson og fl., 2013).
Drangajökull mass balance, using geodetic methods
has revealed that the decline of Drangajökull since the
mid-20th century is much slower than for most other
glaciers in Iceland; the average mass balance rate in
1946–2011 was -0.26±0.04 m a−1 water equivalent
(Magnússon et al., 2016). Only two outlet glaciers in
Iceland (both from S-Vatnajökull) have been reported
with rates of mass loss as close to equilibrium during
a similar time period (Hannesdóttir et al., 2015). This
study was aimed to provide fundamental data, i.e.
the subglacial topography of Drangajökull, to ongo-
ing studies within the frame of the ANATILS project
(http://www.anatils.com/), in order to understand and
constrain better the evolution of Drangajökull during
the Holocene.
DATA AND METHODS
Acquisition and Processing of the RES data
The RES data used in this study was obtained in five
survey days from 25 to 31 March, 2014, and spans
∼590 km (Figure 2). The separation between the pro-
files, which are usually driven in roughly down or up
slope direction, was typically 200–300 m but reaches
up to 650 m on the steep slopes of SE-Drangajökull.
JÖKULL No. 66, 2016 3