2.6 Old ice: Sea ice that has survived at least one
has been deposited on the shore by retreating
summer's melt. Most topographic features are
high water.
smoother than on first-year ice. May be subdi-
3.4.2 GROUNDED HUMMOCK: Hummocked grounded ice
vided into second-year ice and multi-year ice.
formation. There are single grounded hummocks
2.6.1 SECOND-YEAR ICE: Old ice which has survived
and lines (or chains) of hummocks.
only one summer's melt. Because it is thicker
STAMUKHA*: A hummock or ridge of grounded
and less dense than first-year ice, it stands higher
ice, typically on an isolated shoal, formed by
out of the water. In contrast to multi-year ice,
heaping up of ice blocks.
summer melting produces a regular pattern of
numerous small puddles. Bare patches and
puddles are usually greenish-blue.
4. PACK ICE: Term used in a wide sense to include
2.6.2 MULTI-YEAR ICE: Old ice up to 3 m thick or more
any area of sea ice, other than fast ice, no matter
which has survived at least two summers' melt.
what form it takes or how it is disposed.
Hummocks even smoother than in second-year
ice, and the ice is almost salt-free. Colour, where
4.1 Ice cover: The ratio of an area of ice of any con-
bare, is usually blue. Melt pattern consists of
centration to the total area of sea surface within
large interconnecting irregular puddles and a
some large geographic locale; this locale may be
well-developed drainage system.
global, hemispheric, or prescribed by a specific
oceanographic entity such as Baffin Bay or the
3. FORMS OF FAST ICE
Barents Sea.
3.1 Fast ice: Sea ice which forms and remains fast
4.2 Concentration: The ratio expressed in tenths or
along the coast, where it is attached to the shore,
oktas describing the mean areal density of ice in a
to an ice wall, to an ice front, between shoals or
given area.
grounded icebergs. Vertical fluctuations may be
4.2.1 COMPACT PACK ICE: Pack ice in which the con-
observed during changes of sea-level. Fast ice may
centration is 10/10 (8/8) and no water is vis-
be formed in situ from sea water or by freezing of
ible.
pack ice of any age to the shore, and it may ex-
tend a few metres or several hundred kilometres
4.2.1.1 Consolidated pack ice: Pack ice in which the
from the coast. Fast ice may be more than one
concentration is 10/10 (8/8) and the floes are
year old and may then be prefixed with the ap-
frozen together.
propriate age category (old, second-year, or multi-
year). If it is thicker than about 2 m above sea
4.2.2 VERY CLOSE PACK ICE: Pack ice in which the con-
level it is called an ice shelf.
centration is 9/10 to less than 10/10 (7/8 to less
3.1.1 YOUNG COASTAL ICE: The initial stage of fast ice
than 8/8).
formation consisting of nilas or young ice, its
4.2.3 CLOSE PACK ICE: Pack ice in which the concen-
width varying from a few metres up to l00200
tration is 7/10 to 8/10 (6/8 to less than 7/8), com-
m from the shoreline.
posed of floes mostly in contact.
3.2 Icefoot: A narrow fringe of ice attached to the
4.2.4 OPEN PACK ICE: Pack ice in which the ice con-
coast, unmoved by tides and remaining after the
centration is 4/10 to 6/10 (3/8 to less than 6/8),
fast ice has moved away.
with many leads and polynyas, and the floes
are generally not in contact with one another.
3.3 Anchor ice: Submerged ice attached or anchored
to the bottom, irrespective of the nature of its for-
mation.
3.4 Grounded ice: Floating ice that is aground in
*This term does not appear in the WMO from Sea Ice No-
shoal water (cf. stranded ice).
menclature. The definition was instead taken from The Glos-
sary of Geology (1980). Bates, R.L. and J.A. Jackson (Ed.),
3.4.1 STRANDED ICE: Ice which has been floating and
American Geological Institute, Falls Church, VA, p. 607.
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