Jökull - 01.12.1973, Page 3

JOKULL
Á R S R I T
JÖKLARAN NSÓKNAFÉLAGS ÍSLANDS
23. ÁR REYKJAVÍK 1973
ERTS-1 Image of the Vatnajökull Area: Generaí Comments1
RICHARD S. WILLÍ'AMS, JR.
U. S. GEOLOGICAL SURVEY, RESTON, VIRGINIA
SIGURDUR THORARI NSSON
SCIENCE INSTITUTE, UNIVERSITY OF ICELAND
ABSTRACT
The image of Vatnajökull represents the new
type of high resolution satellite imagery which
is being used to study Iceland’s dynamic natural
environment. During each 18-day cycle, the
ERTS-1 satellite makes 10 passes over Iceland,
from east to west, and if the tape recorder is
on, acquires 3 to 5 images, each 180 km X 180
km square, on each pass. Four spectral bands
are imaged, one each in the green and the red,
two in the near-infrared. Under conditions of
low solar illumination the geologic structure
and glacial and terrain morpliology are en-
hanced. The snowline on the sandur and the
snout of Skeiðarárjökull and the frozen and
snow-covered lakes of Thórisvatn, Langisjór,
and Grœnalón, can be clearly seen. Prominent
glaciological features include the recessional
moraines in front of the snouts of several out-
let glaciers of Vatnajökull and Hofsjökull, the
medial moraines at Dyngjujökull and Veðurár-
rönd, and the prominent surface expression of
subglacial volcanic features.
INTRODUCTION
Tlie extraordinary view of the Vatnajökull
area, wliich appears on this year’s cover of
Jökull, is one of many images of Iceland which
have been acquired by the first Earth Resources
Technology Satellite, ERTS-1, since its launch
on 23 July 1972. This image, and others of
different parts of Iceland represent the first
time that high resolution satellite imagery has
been used to study environmental phenomena
in Iceland (Williams and others, 1973, Pálma-
dóttir, 1973a). Previous studies of sea ice around
Iceland and of thermal emission from volcanic
eruptions of Surtsey and Elekla have been
carried out using the poorer resolution of
weather satellite imagery. It is anticipated that
many future scientific articles will result from
the study of the ERTS-1 satellite images of Ice-
land. It is also expected that many of these
1) Publication authorized by the Director, U. S.
Geological Survey.
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JÖKULL 23. ÁR 1