Sea Ice Observations during Southern Ocean GLOBEC

Sea ice observations on the Southern Ocean GLOBEC cruises were conducted according to standardized protocols developed and utilized by members of the Antarctic Sea Ice Processes and Climate working group (co-sponsored by SCAR and GlOCHANT).

Related datasets:
ice properties, ice thickness, snow pits

More details regarding methodology can be found at http://www.scar.org/GLOCHANT/ASPeCt/seaiceobs.htm or by contacting Dr. C.H. Fritsen at cfritsen@dri.edu.

OPEN WATER (OpnWtrCode):
Code --- Description
0 --- No openings
1 --- Small cracks
2 --- Very narrow breaks, <50m

3 --- Narrow breaks, 50-200 m
4 --- Wide breaks, 200-500 m
5 --- Very wide breaks, >500 m
6 --- Lead/coastal lead
7 --- Polynya/coastal polynya
8 --- Water broken only by small scattered floes
9 --- Open sea

ICE CONCn (IceCon): to be expressed in tenths.

ICE TYPE (ITypeCode):
Code --- Description
10 --- Frazil
11 --- Shuga
12 --- Grease
20 -- Nilas
30 --- Pancakes
40 --- Young grey ice, 0.1-0.15 m
50 --- Young grey-white ice, 0.15-0.3 m
60 --- First year, 0.3-0.7 m
70 --- First year, 0.7-1.2 m
80 --- First year, >1.2 m
85 --- Multiyear floes
90 --- Brash
95 --- Fast ice

SEA ICE (IThkns) AND SNOWTHICKNESS (SnoThkns): to be expressed in centimetres.

FLOE SIZE (FloSzCode):
Code --- Description
100 --- Pancakes
200 --- New sheet ice
300 --- Brash/broken ice
400 --- Cake ice, <20 m

500 --- Small floes, 20-100 m
600 --- Medium floes, 100-500 m
700 --- Large floes, 500-2000 m
800 --- Vast floes, >2000 m

SNOW TYPE (SnoTypCode):
Code --- Description
0 --- No snow observation
1 --- No snow, no ice or brash
2 --- Cold new snow, < 1 day old
3 --- Cold old snow
4 --- Cold wind-packed snow
5 --- New melting snow (wet new snow)
6 --- Old melting snow
7 --- Glaze
8 --- Melt slush
9 --- Melt puddles
10 --- Saturated snow (waves)
11 --- Sastrugi

**TOPOGRAPHY (TopoCode):**
Code	Description
100	Level ice
200	Rafted pancakes
300	Cemented pancakes
400	Finger rafting
5xy	New, unconsolidated ridges (no snow)
6xy	New ridges filled with snow or a snow cover
7xy	Consolidated ridges (no weathering)
8xy	Older, weathered ridges
x values	Areal Coverage
0	0-10%
1	10-20%
2	20-30%
3	30-40%
4	40-50%
5	50-60%
6	60-70%
7	70-80%
8	80-90%
9	90-100%
y values	Avg. Sail Height
1	0.5 m
2	1.0 m
3	1.5 m
4	2.0 m
5	3.0 m
6	4.0 m
7	5.0 m

The following weather observation codes and descriptions are from the "National Weather Service Observing Handbook No. 1", Marine Surface Weather Observations, August 1995. U.S. Department of Commerce, Silver Spring, MD.

VISIBILITY (visib):
Code --- Visibility in m/km
90 --- less than 50 m
91 --- 50 but less than 200 m
92 --- 200 but less than 500 m
93 --- 500 but less than 1000 m
94 --- > 1 but less than 2 km
95 --- > 2 but less than 4 km
96 --- > 4 but less than 10 km
97 --- > 10 but less than 20 km
98 --- > 20 but less than 50 km
99 --- > 50 km or more

TOTAL CLOUD COVER (cldcvr): to be expressed in eighths; -1 = Sky obscured by fog, snow or other met. phenom.

**PRESENT WEATHER (wx):**
Code	Description
	Change of sky during past hour
0	Cloud development not observable
1	Clouds dissolving or becoming less developed
2	State of the sky on the whole unchanged
3	Clouds generally forming or developing
	Phenomena in past hour but not at time of obs
28	Fog (in past hour, but not at time of obs.)

36	Slight or moderate drifting snow, low (below eye level)
37	Heavy drifting snow, low (below eye level)
38	Slight or moderate drifting snow, high (above eye level)
39	Heavy drifting snow, high (above eye level)
	Fog at the time of observation
41	Sky visible Fog in patches (visibility may be greater than 1/2 nm)
42	Sky visible Fog has become thinner in past hour
43	Sky invisible For has become thinner in past hour
44	Sky visible Fog, no change in past hour
45	Sky invisible Fog, no change in past hour
46	Sky visible Fog has begun or thickened in past hour
47	Sky invisible Fog has begun or thickened in past hour
	Drizzle
50	Intermittent Slight drizzle
56	Slight Freezing drizzle
	Rain (Not falling as showers)
60	Intermittent Slight rain
	Solid precipitation not falling as showers
70	Intermittent Slight snow in flakes
71	Continuous Slight snow in flakes
72	Intermittent Moderate snow in flakes
73	Continuous Moderate snow in flakes
74	Intermittent Heavy snow in flakes
75	Continuous Heavy snow in flakes
76	Diamond dust (with or without fog)
77	Snow grains (with or without fog)
	Solid precipitation in showers
85	Slight Shower of snow
86	Moderate or heavy Shower of snow