Working Group No. 6 "Interpretation of Ice" was es-
tablished in 1957 and therefore is reporting for the
first time. It deals with ice of different types and
conditions in as distantly separated areas as the
Arctic and the Antarctic.
In developing a true knowledge of the ice conditons,
whether the ice is formed by the freezing of sea water
or formed on land masses, photo interpretation generally
offers the specialist an invaluable aid. Unfortunately,
this Science seems in many cases not to be known well
enough and ice photos are used merely for illustrating
purposes. Delegates and collaborators active in Work-
ing Group No. 6 and representatives from Canada, Eng-
land, Finland, Japan, Sweden and U.S.A. are, however,
reporting many interesting methods of application of
Ice-interpretation. According to published material
Ice photo reconnaissance and interpretation of Ice are
used for special purposes also of several other coun-
tries, among others Denmark and U.S.S.R. In addition
to a survey of the field, this report contains a series
of papers on ice interpretation. These papers will be
the subject of discussion at the Working Group No. 6
sessions in London in September 1960. They are:
Dr. Geza Teleki, Professor of Geology at George Wash-
ington University, and Researcher for the Artic Insti-
tute of North America:
"THE RELATION OF SEA ICE FORECAST
AND AERIAL PHOTOGRAPHS IN ARCTIC REGIONS,"
Dr. Terence Armstrong, Scott Polar Research Institute,
Cambridge, England:
"ICE ON THE NORTHERN SEA ROUTE
IN REIATION TO THE USE OF PHOTOGRAMMETRY."
Miss Moira Dunbar, Directorate of Physical Research
(Geophysics), Defense Research Board, Department of
National Defense, Ottawa, Canada:
"ICE NAVIGATION AND THE ROLE OF PHOTO-INTERPRETATION
IN THE CANADIAN ARCTIC ARCHIPELAGO."
Dr. Erkki Palosou, Institute of Marine Research,
Helsinki (Helsingfors), Finland:
"ON THE EMPLOYMENT OF AERIAL PHOTOGRAPHY
FOR ICE RESEARCH IN THE BALTIC."
Dr. Valter Schytt, Institute of Geography, Stockholm
University, Stockholm, Sweden:
"GLACIER INVENTORY FROM AIR PHOTOGRAPHS."
Some factors relative to the general native, and in-
terpretation of sea ice and land ice are discussed in
the following paragraphs.
ATR PHOTOGRAPHIC SEA ICE RECONNAISSANCE
The documentary character of the photographic pic-
ture makes photography an inestimable aid in Arctic
Research, especially in the study of Sea Ice extending
over vast areas. Regular flights over areas of topical
interest will give the photo interpreter a clear view of
the conditions therein and of the îce drift. The photos
provide information about the ice not only concerning
its concentration, size, topography, age and snow-cover-
age etc., but regarding temporary open or frozen cracks,
leads, pools and polynyas as well, and of the varying
position of the ice edge. Snow-covered and seemingly
flat ice fields, too, with a closer examination will
usually show up a characteristic pattern of pressure
ridges and frozen cracks etc., all of great importance
for the photo interpreter when identifying different
Sections of the field. On the basis of the photo inter-
preters' reports, and of meteorological data and infor -
Archives 6
mation concerning currents, etc., the specialist will be
able to forecast the probable navigability in the area in
question and to present relatively reliable long-range
ice forecasts.
To get an idea of the ice conditions in the center of
the Arctic Ocean, the author practiced air-photo recon-
naissance using a Swedish-built Hasselblad camera on a
flight with SAS Round-the-world via Bangkok and Japan.
The time was at night on May 23-24, 1958. From Alaska
the plane followed broadly speaking the 144° Meridian
(Long. West) at an altitude of 21,000 feet (6,400 m.)
straight in the direction of the geographical North Pole.
At Lat. 84° 25” North, not far from the so-called Ice-
Pole or Pole-of-Inaccessibility, in the center of the
Arctic Pack, the ice conditions could be characterized
as vast consolidated fields of North Polar Ice. Record-
ed in the photos, however, was a frozen crack serpentin-
ing along the snow-covered field of hummocked polar ice,
richly patterned by pressure ridges. The negative scale
was 1:70,000.
At 22.10 G.M.T. the Soviet Drifting Station North
Pole 7 (SP-7) was passed at a distance of only 22 nauti-
cal miles. The still heavily packed ice in this area
had at intervals a more cracked appearance with a net-
Work of pressure ridges &nd frozen, narrow cracks with
dark ice not covered in snow. The width of the cracks
varied between 15 and 50 feet or &bout 5 to 15 m. Small
pools in the pictures were measured to &bout 100 x 100
and 100 x 160 feet or 30 x 30 and 30 x 50 m. It is
worth mentioning that there was severe cracking of the
floe on which SP-7 stood in December 1958 (compere
Figure 1), and this necessitated moving some buildings,
but the station was able to continue its work (Polar Re-
cord, Vol. 9, No. 63, September 1959, p. 570).
The geographical North Pole was reached at 2300 hours
G.M.T. precisely. The event was celebrated with a North
Pole-turn. Thus the author had the opportunity of study-
ing more closely the ice conditions at the actual top of
the world. An enormous field of completely consolidated,
hummocked, snow-covered polar ice with a rich pattern of
pressure ridges extended in all directions. Thanks to
the bright rays of the midnight sun the ridges stood out
in beautiful relief.
From the Pole the plane followed the 10° Meridian
(Long. East) in the direction towards the west coast of
Spitsbergen. In this part of the Polar Basin the charac-
ter of the polar pack was different, with frozen cracks,
leads and polynyas at intervals, as an example see
Figure 2. The photo was taken at Lat. 89° North,
Long. 10° East. All cracks and other water openings
were then ice-covered. The different shades of gray in
the openings, however, proved that the freezing had not
been simultaneous, and the almost black surfaces indicat-
ed that the pack ice recently had been in heavy motion.
Between the different floes there were cracks and open
basins, frozen, but not yet snow-covered. The two lar-
ger basins, of type Polynya, in the lower part of the
picture were about 660 feet across and 1300 feet long,
or 200 x 400 m. These approximate values will also give
the reader an idea of the size of the different ice
floes. The larger floes adjacent to the basins were
about 1300 x 1800 feet or 400 x 550 m. and were all so-
called Medium Floes.
The pack ice in these regions is always moving. In
its motion the ice opens and shuts, and a certain number
of lanes are always present, sometimes of considerable
width. The wind produces rotation as well as transla-
tion, thereby causing a screwing effect with an exces-
give pressure at the jutting corners of the floes. A
hummock of loose ice blocks often will be the result.
In stormy weather, fields, floes and blocks are pressed
hard to each other, thereby forming mighty pressure
ridges.
In the western part of the Polar Basin, south and
west of a line from the New Siberian Islands to the
geographical North Pole and Ellesmero Island, the ice
drift bends in a great circle towards the Greenland Sea.
Within the eastern part of the Basin, on the other hand,
&djacent to the Cenadian arctic archipelago and Alaska,
the ice drift follows an anticyclonic pattern, i.e.
