Sea Ice Symbols Fact Sheet
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Row A
Total concentration: the ice coverage of an area determined by its concentration and expressed in tenth (in this example, 9/10)
Row B
Partial concentration: the break-down of the total ice coverage expressed in tenths and graded by thickness. The thickest starting from the left and in this example, 1/10 is the thickest.
Row C
Stage of development: the type of ice in each of the grades, determined by its age, that is 1/10 is medium first-year ice (1. ), 6/10 is grey-white ice (5) and 2/10 is new ice (1). Trace of old ice is represented on the lefthand side (outside the egg) by the number 7.
Row D
Floe Size: the form of the ice determined by its floe size for each section. In this example, big floes (5) for medium first-year ice (1. ); small floes (3) for grey-white ice (5); and undetermined, unknown or no form floes (x) for new ice (1).
Note: When an ice type has a dot (.) every other value to the left of it is also considered to have a dot.
| Column | Description |
|---|---|
| E | Trace of ice thicker/older then Sa |
| F | Thickest |
| G | Second thickest |
| H | Third thickest |
| I | Additional groups |
| Symbol | Description |
|---|---|
 | Open Water |
 | Ice Free |
 | Bergy Water |
 | Fast Ice |
| Description | Thickness | Code |
|---|---|---|
| New Ice | < 10 cm | 1 |
| Nilas;Ice Rind | < 10 cm | 2 |
| Young Ice | 10-30 cm | 3 |
| Grey Ice | 10-15 cm | 4 |
| Grey-white Ice | 15-30 cm | 5 |
| First-year Ice | 30 cm | 6 |
| Thin First-year Ice | 30-70 cm | 7 |
| Medium First-year Ice | 70-120 cm | 1. |
| Thick First-year Ice | > 120 cm | 4. |
| Old Ice | 7. | |
| Second-year | 8. | |
| Multi-year | 9. | |
| Ice of Land Origin |  | |
| Undetermined/Unknown | X |
| Description | Width | Code |
|---|---|---|
| Pancake ice | 0 | |
| Small ice cake; brash ice | < 2 m | 1 |
| Ice cake | 2 - 20 m | 2 |
| Small floe | 20 – 100 m | 3 |
| Medium floe | 100 – 500 m | 4 |
| Big floe | 500 – 2000 m | 5 |
| Vast floe | 2 – 10 km | 6 |
| Giant floe | > 10 km | 7 |
| Fast Ice | 8 | |
| Icebergs* | 9 | |
| Undetermined, unknown or no form | X | |
| Strips (concentration = C) |  |
| Diagram | Concentration | Description |
|---|---|---|
 | < 1/10 | Open Water |
 | 1-3/10 | Very open drift |
 | 4-6/10 | Open drift |
 | 7-8/10 | Close pack |
 | 9/10 | Very close pack |
 | 9+/10 | Very close pack |
 | 10/10 | Compact / Consolidated ice |
| Colour* | Description |
|---|---|
 | Ice Free |
 | < 1 Tenth Ice |
 | 1-3 Tenths Ice |
 | 4-6 Tenths Ice |
 | 7-8 Tenths Ice |
 | 9-10 Tenths Ice |
 | Fast Ice |
 | Undefined Ice |
| Optional | |
 | 7 Tenths New Ice |
 | 9+-10 Tenths Nilas, Grey Ice ** |
Areas for which no information is known are identified accordingly.
* Colour is based on total ice concentration.
** The optional colour indicating 9+-10 tenths of nilas or grey ice indicates level ice, mainly on leads; it is not used for ice broken into brash or ice cakes or for concentrations less than 9+ tenths.
| Colour | Description | Thickness |
|---|---|---|
 | Ice Free | |
 | Open Water | |
 | New Ice | < 10 cm |
 | Grey Ice | 10-15 cm |
 | Grey-White Ice | 15-30 cm |
 | First-Year Ice | >= 30 cm |
 | Thin First-Year Ice | 30-70 cm |
 | Medium First-Year Ice | 70-120 cm |
 | Thick First-Year Ice | 120 cm > |
 | Old Ice | |
 | Second-Year Ice | |
 | Multi-Year Ice | |
 | Fast Ice | |
 | Undefined Ice | |
 | Icebergs |
Areas for which no information is known are identified accordingly.
Colour is based on stage of development of predominant ice.
See also: Lake Ice Symbols Fact Sheet
- Date Modified: