Jökull - 01.01.2004, Side 18

Eyjólfur Magnússon et al.
Figure 1. The area surveyed with the airborne EMISAR system in August 1998. Rectangles delineate swaths
of individual flight-lines. – Svæðið sem var mælt með EMISAR radarnum í ágúst 1998.
Satellite and airborne remote sensing methods
have facilitated detailed mapping of large areas, in-
cluding glaciers. High resolution radar images can
be acquired with synthetic aperture radar (SAR) inde-
pendent of weather conditions. The problem of neg-
ligible contrast in the visible range of light, present
in DEMs derived from aerial photographs of glaciers,
is irrelevant for this new technique. One applica-
tion of SAR is interferometric SAR (InSAR), which
in the recent years has been successfully used in Ice-
land for studying crustal deformation ( e.g. Vadon and
Sigmundsson, 1997) as well as glacier surface move-
ments (Jónsson et al., 1998; Alsdorf and Smith 1999;
Björnsson et al., 2001; Guðmundsson et al., 2002;
Fischer et al., 2003) with data from the ERS-1/-2
satellites. InSAR can also be applied to topographi-
cal mapping (e.g. Rosen et al., 2000) but its usage in
Iceland for that purpose has been very limited (Als-
dorf and Smith 1999; Hall et al., 2000; Haack et al.,
2000).
SAR data covering around 1/10 of Iceland was
acquired in August 1998, using an airborne EMI-
SAR system from the former Electromagnetic In-
stitute (EMI, now Electromagnetic Systems) of the
Technical University of Denmark. The EMISAR sys-
tem consists of fully polarimetric SAR (PolSAR) at L-
and C-band (24 cm and 5.6 cm, respectively) (Chris-
tensen et al., 1998) and a single-pass, cross-track In-
SAR at C-band (Madsen et al., 1996). The InSAR
consists of two antennae, which were mounted on the
side of a Gulfstream jet from the Royal Danish Air-
force with 1.14 m separation. The measured data,
which consist of both PolSAR and InSAR data, cover
most of the Eastern Volcanic Zone, including western
18 JÖKULL No. 54