Sea Ice Observations
These are WMO physical observations made by the RA and could be subjective.
R 162
Msg# Size To From @ BBS Date Time Title
162 PN 6425 NHG ZHF44 24-Aug-91 18:25 ICE INFO
SYNOPTIC REPORT - INCLUSION OF SECTION 2
When doing an ice observation it will be necessary to find a
point where you have good all round visibility. You will also
have to make certain approximations about the conditions of the
ice.
The section commencing 222 can be added to the normal MET
coding for the weather. This should start with the figures 222//.
The first group of the section describes the sea temperature.
This is described in the form 0,sn,Tw,Tw,Tw. Where sn is the sign
for the temperature (Positive or negative) and TwTwTw is the
temperature of the sea.
The next code is, ICE ci,Si,bi,Di,zi this describes the
prevailing ice conditions.
ICE ci,Si,bi,Di,zi
Example of ice coding
89061 11462 83633 10011 21007 49922 57010 60064 76672 886//
222// 01018 ICE 44896
333 10015 20000 88710 90452 90577=
CODE TABLES RELEVANT TO SECTION 2
Concentration or arrangement of sea ice
Code
0 - No sea ice in sight.
1 - Ship in open lead > 1nm wide, or ship in fast ice with
boundary beyond limit of visibility.
2 - Sea ice present in concentrations < 3/10, open water or very
open pack ice.
3 - 4/10 to 6/10 open pack ice.
4 - 7/10 to 8/10 close pack ice.
5 - 9/10 or more, but not 10/10, very close pack ice.
6 - Strips and patches of pack with open water between.
7 - Strips or patches of close or very close pack ice with areas
of lesser concentrations between.
8 - Fast ice with open water, very open or open pack ice to
seaward of the ice boundary.
9 - Fast ice with close or very close pack ice to sea of the ice
boundary.
/ - Unable to report, due to darkness, lack of visibility, or
ship is more than 0.5 nm away from the ice edge.
Note: All codes are written with ships in mind so it is necessary
to make approximations in some cases.
Fast Ice:- Sea ice which remains fast along the coast, where
it is attached to the shore.
Open Pack Ice:- Composed of floes seldom in contact and with
many leads.
Close Pack Ice:- Composed of floes mostly in contact.
Stage of Development (Si).
Code
0 - New ice only (Frazil ice, grease ice, slush, shuga).
1 - Nilas or ice rind, less than 10cm thick.
2 - Young ice (grey ice, grey-white ice), 10-30cm thick.
3 - Predominately new and/or young ice with some first year ice.
4 - Predominately thin first year ice with some new and/or young
ice.
5 - All thin first year ice (30-70 cm thick).
6 - Predominately medium first year ice (70-120 cm thick) and
thick first year ice (>120 cm thick) with some thinner
(younger) first year ice.
7 - All medium and thick first year ice.
8 - Predominately medium and thick first year ice with some old
ice (usually more than 2 metres thick).
9 - Predominately old ice.
/ - Unable to report, because of darkness lack of visibility or
because only ice of land origin is visible or because ship
is more than 0.5nm from the ice edge.
Note:
Frazil Ice:- Fine spicules or plates of ice in suspension in the
water.
Grease Ice:- A later stage of freezing than frazil ice, when the
spicules and plates of ice have coagulated to form
a thick soupy layer on the surface of the water.
Grease ice reflects very little light giving it a
matt appearance.
Slush:- Snow which is saturated and mixed with water.
Shuga:- An accumulation of spongy white ice lumps, a few cms
across, formed from grease ice or slush.
New Ice:- A general term for floating ice recently formed. It
includes Frazil ice, grease ice, slush, shuga, ice
rind, nilas and pancake ice.
Young Ice:- Floating ice in the transition stage from new ice and
first year ice. Snow cover is mostly moist and
slushy.
First Year Ice:- Consists of pink Elephants and Golliwogs.
Old Ice:- Floating ice more than two years old, up 3 metres or
more thick.
Nilas:- A thin elastic crust of floating ice, easily bending on
waves and rafting under pressure. It has a matt surface
and is up to 10 cm thick.
Ice Rind:- A brittle shiny crust of floating ice, formed on a
quiet surface by direct freezing or from grease ice.
Ice of Land Origin(bi).
Code
0 - No ice of land origin.
1 - 1-5 icebergs, no growlers or bergy bits.
2 - 6-10 icebergs, no growlers or bergy bits.
3 - 11-20 icebergs, no growlers or bergy bits.
4 - Up to and including 10 growlers and bergy bits - no bergs.
5 - More than 10 growlers and bergy bits - no bergs.
6 - 1-5 bergs, with growlers and bergy bits.
7 - 6-10 bergs, with growlers and bergy bits.
8 - 11-20 bergs with growlers and bergy bits.
9 - More than 20 bergs, with growlers and bergy bits - a major
hazard to navigation.
/ - Unable to report, because of darkness, lack of visibility or
because only sea ice is visible.
Note:
Bergy Bit:- A piece of floating ice, generally 5 metres above sea
level and not more than 10 metres across. It is
generally of ice glacier ice.
Growlers:- A piece of ice almost awash, smaller than a bergy bit.
True Bearing of Principal Ice Edge(Di).
Code
0 - Ship in shore or flaw lead.
1 - Principal ice edge towards the NE.
2 - Principal ice edge towards E.
3 - Principal ice edge towards SE.
4 - Principal ice edge towards S.
5 - Principal ice edge towards SW.
6 - Principal ice edge towards W.
7 - Principal ice edge towards NW.
8 - Principal ice edge towards N.
9 - Not determined.
/ - Unable to report, because of darkness, lack of visibility or
because only ice of land origin is visible.
Note:
Usually we use 9 for this group as we seldom have anything that
distinct.
Present Ice Situation and Trend of Conditions Over Preceding 3
hours.
Code
0 - Ship in open water with floating ice in sight.
1 - Ship in easily penetrable ice : conditions improving.
2 - Ship in easily penetrable ice : conditions not changing.
3 - Ship in easily penetrable ice : conditions worsening.
4 - Ship in ice difficult to penetrate : conditions improving.
5 - Ship in ice difficult to penetrate : conditions not changing.
6 - Ice forming and floes freezing together.
7 - Ice under slight pressure.
8 - Ice under moderate or severe pressure.
9 - Ship beset.
/ - Unable to report, because of darkness or lack of visibility.
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