A

F

G

N

E

B

P

D

L

I

H

K

F

G

G

O

J F

C

F

M

IF E

Q Q

R

R

S

S

S

S

T

U

V

W

X

X

Y

155°W 150°W 145°W

160°W

160°W

165°W

165°W

170°W

170°W

175°W

175°W

180°

170°E 175°E 180°

75°N

75°N

70°N

70°N

65°N

65°N

14

14

16

19

 ́

17

U/I

ICE EDGE

COLOR CODES BASED ON TOTAL CONCENTRATION

1-3 TENTHS

LESS THEN

1 TENTH

ICE FREE

9-10 TENTHS

7-8 TENTHS

4-6 TENTHS

UNDEFINED

ICE

ICE SHELF

FAST ICE

(TEN TENTHS)

ICE ANALYSIS

Chukchi Sea

NATIONAL/NAVAL ICE CENTER

Analysis Week 24 Oct 2008

Data Sources Date

RADARSAT...........24 Oct

ENVISAT/GMM...23 - 24 Oct

Analysts: Pacheco Vega, Christian AG3

Szorc, Chris (NAVY CIV)

UNCLASSIFIED

CM = THEORETICAL ICE THICKNESS IN CENTIMETERS

 ́

NM = 168HR ANAL DRIFT VECTORS IN NAUTICAL MILES

IF = ICE FREE

A 2

1

X

B 3

1 2

3 1

3 X

C 3

1

X

D 5

3 2

3 1

3 X

E 6

2 4

3 1

3 X

F 6

3 3

3 1

3 X

G 7

3 4

3 1

3 X

H 7

4 3

3 1

3 X

I 7

5 2

3 1

3 X

J 7-9

3 5

3 1

K 7-9

5 3

3 1

L 7-9

7 1

3 1

M 8

2 6

3 1

3 X

N 8

4 4

3 1

3 X

O 8

5 3

3 1

3 X

P 8

6 2

3 1

3 X

Q 8-10

7 2

3 1

R 9

4 5

3 1

3 X

S 9

6 3

3 1

3 X

T 9

7 2

3 1

3 X

U 9+

1 6 2

7 3 1

V 9+

3 1 5

8● 7 3

W 9+

6 3

3 1

3 X

X 9+

8 1

3 1

3 X

Y 9+

8 1

3 1
IF

A A

B

B

C

C

C

D

D

E

F

G

H

H I

J

J

K

K

K

K

K L

L

M

N

O

P

Q

R

R

S

T

U

ICE EDGE

155°W 150°W 145°W

160°W

160°W

165°W

165°W

170°W

170°W

175°W

175°W

180°

170°E 175°E 180°

75°N

75°N

70°N

70°N

65°N

65°N

16

14

20

21

10 17

10

 ́

 ́

 ́

COLOR CODES BASED ON TOTAL CONCENTRATION

1-3 TENTHS

LESS THEN

1 TENTH

ICE FREE

9-10 TENTHS

7-8 TENTHS

4-6 TENTHS

UNDEFINED

ICE

ICE SHELF

FAST ICE

(TEN TENTHS)

ICE ANALYSIS

Chukchi Sea

NATIONAL/NAVAL ICE CENTER

Analysis Week 27 - 31 Oct 2008

Data Sources Date

RADARSAT......25 - 27 Oct

ENVISAT/GMM...26 - 27 Oct

QUIKSCAT...........26 Oct

Analysts: Miller, Josh MST1

Szorc, Chris (NAVY CIV)

UNCLASSIFIED

CM = THEORETICAL ICE THICKNESS IN CENTIMETERS

 ́

NM = 168HR ANAL DRIFT VECTORS IN NAUTICAL MILES

IF = ICE FREE

A 3

1 2

3 1

3 X

B 5

2 3

3 1

3 X

C 6

3 3

3 1

3 X

D 7

3 4

3 1

3 X

E 7

4 3

3 1

3 X

F 8

3 5

3 1

2 X

G 8

3 5

3 1

3 X

H 8

5 3

3 1

3 X

I 8

6 2

3 1

3 X

J 9

3 6

3 1

3 X

K 9

6 3

3 1

3 X

L 9

7 2

3 1

3 X

M 9

8 1

3 1

3 X

N 9+

1 5 3

7 3 1

O 9+

1 6 2

7 3 1

P 9+

3 1 5

8● 7 3

Q 9+

5 4

3 1

R 9+

6 3

3 1

S 9+

7 2

3 1

T 9+

8 1

3 1

U 10

8 2

3 1

3 X
J

A

T

U

W

X

Y

Z

BB

AA

L Q

I

DD

L

S

DD

DD

DD

R

D

H

K

E

N

DD

CC

CC

P

M

C

DD

B

G

V

F

O

Q

S

IF

J

155°W 150°W 145°W

160°W

160°W

165°W

165°W

170°W

170°W

175°W

175°W

180°

170°E 175°E 180°

75°N

75°N

70°N

70°N

65°N

65°N

Ice Edge

36

32

32

25

 ́

 ́

 ́

 ́

 ́

13 33

17

49

31

 ́

7

COLOR CODES BASED ON TOTAL CONCENTRATION

1-3 TENTHS

LESS THEN

1 TENTH

ICE FREE

9-10 TENTHS

7-8 TENTHS

4-6 TENTHS

UNDEFINED

ICE

ICE SHELF

FAST ICE

(TEN TENTHS)

ICE ANALYSIS

Chukchi Sea

NATIONAL/NAVAL ICE CENTER

Analysis Week 10 - 14 Nov 2008

Data Sources Date

ENVISAT/GMM........10 Nov

Analysts: Szorc, Chris (NAVY CIV)

UNCLASSIFIED

CM = THEORETICAL ICE THICKNESS IN CENTIMETERS

 ́

NM = 168HR ANAL DRIFT VECTORS IN NAUTICAL MILES

IF = ICE FREE

A 0-1

1

B 2

1

X

C 2-4

1 2

3 1

D 4

2 2

3 1

3 X

E 4

1

X

F 5

2 3

3 1

3 X

G 5

1

X

H 6

4 2

3 1

3 X

I 7

2 5

3 1

3 X

J 7

4 3

3 1

3 X

K 7

6 1

3 1

3 X

L 7

1

X

M 7-9

4 4

3 1

N 8

2 6

3 1

3 X

O 8

6 2

3 1

3 X

P 8-10

5 4

3 1

Q 9

5 4

3 1

3 X

R 9

8 1

3 1

3 X

S 9

1

X

T 9+

1 7 1

7 3 1

U 9+

2 1 6

8● 7 3

V 9+

3 5 1

7 3 1

W 9+

3 3 3

8● 7 3

X 9+

4 5

3 1

3 X

Y 9+

6 3

3 1

3 X

Z 9+

7 2

3 1

3 X

AA 9+

8 1

3 1

3 X

BB 9+

3

3

CC 10

8 2

3 1

3 X

DD 10

3

8
G

J

K

M

N

P

R S

V

X

O

U

L

E

T

B

G

D

D

X

F

Q

C

W

W

B

A

I

H

E

IF

B

B

X

X

X

X

155°W 150°W 145°W

160°W

160°W

165°W

165°W

170°W

170°W

175°W

175°W

180°

170°E 175°E 180°

75°N

75°N

70°N

70°N

65°N

65°N

Ice Edge

40

34

27

34

18

 ́

 ́

 ́

 ́

 ́

 ́

32 10

20

5

7 51

COLOR CODES BASED ON TOTAL CONCENTRATION

1-3 TENTHS

LESS THEN

1 TENTH

ICE FREE

9-10 TENTHS

7-8 TENTHS

4-6 TENTHS

UNDEFINED

ICE

ICE SHELF

FAST ICE

(TEN TENTHS)

ICE ANALYSIS

Chukchi Sea

NATIONAL/NAVAL ICE CENTER

Analysis Week 14 Nov 2008

Data Sources Date

ENVISAT/GMM...13 - 14 Nov

Analysts: Szorc, Chris (NAVY CIV)

UNCLASSIFIED

CM = THEORETICAL ICE THICKNESS IN CENTIMETERS

 ́

NM = 168HR ANAL DRIFT VECTORS IN NAUTICAL MILES

IF = ICE FREE

A 1-3

1 1

3 1

B 2

1

X

C 3-5

3 1

3 1

D 4

1

X

E 5

3 2

3 1

3 X

F 7

4 3

3 1

3 X

G 7

1

X

H 8

4 4

3 1

3 X

I 8

6 2

3 1

3 X

J 8

7 1

3 1

3 X

K 8

1

X

L 9+

1 7 1

7 3 1

M 9+

2 1 6

8● 7 3

N 9+

3 5 1

7 3 1

O 9+

3 3 3

8● 7 3

P 9+

5 4

3 1

3 X

Q 9+

6 3

3 1

3 X

R 9+

6 3

3 1

S 9+

7 2

3 1

3 X

T 9+

8 1

3 1

3 X

U 9+

8 1

3 1

V 9+

3

3

W 10

8 2

3 1

3 X

X 10

3

8
A

C

IF

IF

I

E

D F

G

J

O

B

H

E

K

K

H

M

N

L

J

Q

R

T

U

V

W

Y

X

V

P

S

Y

Y

Y

Y

Y

Z Z

AA

AA

AA

155°W 150°W 145°W

160°W

160°W

165°W

165°W

170°W

170°W

175°W

175°W

180°

170°E 175°E 180°

75°N

75°N

70°N

70°N

65°N

65°N

Ic e E

d

g

31 e

47

39

37

22

 ́

 ́

 ́

 ́

 ́

 ́

21 42

35

49

20

41

COLOR CODES BASED ON TOTAL CONCENTRATION

1-3 TENTHS

LESS THEN

1 TENTH

ICE FREE

9-10 TENTHS

7-8 TENTHS

4-6 TENTHS

UNDEFINED

ICE

ICE SHELF

FAST ICE

(TEN TENTHS)

ICE ANALYSIS

Chukchi Sea

NATIONAL/NAVAL ICE CENTER

Analysis Week 17 - 21 Nov 2008

Data Sources Date

RADARSAT...........18 Nov

OLS................17 Nov

ENVISAT/GMM...16 - 17 Nov

Analysts: Szorc, Chris (NAVY CIV)

UNCLASSIFIED

CM = THEORETICAL ICE THICKNESS IN CENTIMETERS

 ́

NM = 168HR ANAL DRIFT VECTORS IN NAUTICAL MILES

IF = ICE FREE

A 0-1

1

B 2

1 1

3 1

3 X

C 3

1

X

D 3-5

1 3

3 1

E 4

3 1

3 1

3 X

F 5

2 3

3 1

3 X

G 6

2 4

3 1

3 X

H 6

4 2

3 1

3 X

I 7

1 6

3 1

3 X

J 7

5 2

3 1

3 X

K 8

2 6

3 1

3 X

L 8

3 5

3 1

3 X

M 8

5 3

3 1

3 X

N 9

5 4

3 1

3 X

O 9+

2 7

7 3

P 9+

2 1 6

9● 7 3

5 3 3

Q 9+

3 4 2

8● 7 3

R 9+

4 5

7 3

S 9+

4 1 4

9● 7 3

5 3 3

T 9+

5 4

3 1

3 X

U 9+

7 2

3 1

3 X

V 9+

7 2

3 1

W 9+

8 1

3 1

3 X

X 9+

3

Y 10

1 9

7 3

8

Z 10

7 3

9 8●

5 5

AA 10

3

8
IF

A

A

B C

C

D

D

E

E

F

F

G

G

G

H

I

J

K

L

M

N

O

P

Q

Q

Q

Q

Q

Q

Q

Q

Q

Q

R

S

S

S

155°W 150°W 145°W

160°W

160°W

165°W

165°W

170°W

170°W

175°W

175°W

180°

170°E 175°E 180°

75°N

75°N

70°N

70°N

65°N

65°N

 ́

 ́

 ́

35

17

17

17

41

56 24

ICE EDGE A 1-3

1 1

3 1

3 X

B 1-3

1 1

3 1

C 3-5

3 1

3 1

3 X

D 5-7

3 3

3 1

3 X

E 5-7

1

X

F 7-9

4 4

3 1

3 X

G 7-9

5 3

3 1

3 X

H 7-9

5 3

3 1

I 9+

2 6 1

7 3 1

3 3 X

J 9+

2 7

7 3

K 9+

2 4 3

9● 7 3

L 9+

3 6

3 1

3 X

M 9+

4 5

3 1

3 X

N 9+

4 5

7 3

O 9+

6 3

3 1

3 X

P 9+

7 2

3 1

3 X

Q 9+

8 1

3 1

3 X

R 9+

3

S 10

3

8

COLOR CODES BASED ON TOTAL CONCENTRATION

1-3 TENTHS

LESS THEN

1 TENTH

ICE FREE

9-10 TENTHS

7-8 TENTHS

4-6 TENTHS

UNDEFINED

ICE

ICE SHELF

FAST ICE

(TEN TENTHS)

ICE ANALYSIS

Chukchi Sea

NATIONAL/NAVAL ICE CENTER

Analysis Week 04 Nov 2010

Data Sources Date

RADARSAT...........04 Nov

ALOS...............04 Nov

ENVISAT/GMM........04 Nov

Analysts: Szorc, Chris (NAVY CIV)

UNCLASSIFIED

CM = THEORETICAL ICE THICKNESS IN CENTIMETERS

 ́

NM = 168HR ANAL DRIFT VECTORS IN NAUTICAL MILES

IF = ICE FREE
I

K

L

J

G

B

L

K

C

K

H

A

K

M

A

D

M

L

G

C

K

F

G

C

G

E

IF

C

N O

P

Q

R

S

S

T

T

T

U

U

V

W

X

X

X

X

X

X

X

X

X

X

X

155°W 150°W 145°W

160°W

160°W

165°W

165°W

170°W

170°W

175°W

175°W

180°

170°E 175°E 180°

75°N

75°N

70°N

70°N

65°N

65°N

ICE EDGE

41

21

20

20

 ́

 ́

 ́

 ́

21

18

52

36

COLOR CODES BASED ON TOTAL CONCENTRATION

1-3 TENTHS

LESS THEN

1 TENTH

ICE FREE

9-10 TENTHS

7-8 TENTHS

4-6 TENTHS

UNDEFINED

ICE

ICE SHELF

FAST ICE

(TEN TENTHS)

ICE ANALYSIS

Chukchi Sea

NATIONAL/NAVAL ICE CENTER

Analysis Week 08 - 12 Nov 2010

Data Sources Date

RADARSAT...........08 Nov

OLS................08 Nov

ENVISAT/GMM........08 Nov

Analysts: Szorc, Chris (NAVY CIV)

UNCLASSIFIED

CM = THEORETICAL ICE THICKNESS IN CENTIMETERS

 ́

NM = 168HR ANAL DRIFT VECTORS IN NAUTICAL MILES

IF = ICE FREE

A 1-3

1 1

3 1

3 X

B 3-5

1 3

3 1

3 X

C 3-5

3 1

3 1

3 X

D 3-5

3 1

3 1

E 3-5

1

X

F 5-7

3 3

3 1

3 X

G 5-7

4 2

3 1

3 X

H 7-9

1 7

3 1

3 X

I 7-9

1 7

7 3

3 3

J 7-9

3 5

3 1

3 X

K 7-9

5 3

3 1

3 X

L 7-9

6 2

3 1

3 X

M 7-9

6 2

3 1

N 9+

1 6 2

9● 7 3

O 9+

2 4 3

9● 7 3

P 9+

3 6

7 3

Q 9+

5 4

3 1

3 X

R 9+

5 4

7 3

S 9+

6 3

3 1

T 9+

7 2

3 1

3 X

U 9+

3

3

V 10

1 9

7 3

8

W 10

2 8

7 3

8

X 10

3

8
H

E

J

L

I T

S

S

R

I

A

W

Q

W

E

F

A

A

D

B

H

C

W

W

H A

H

W

W

U

W

V

P

M N

K

O

W

B

IF

W

G

F

E

Q

A

ICE EDGE

155°W 150°W 145°W

160°W

160°W

165°W

165°W

170°W

170°W

175°W

175°W

180°

170°E 175°E 180°

75°N

75°N

70°N

70°N

65°N

65°N

22

44

22

23

 ́

 ́

 ́

15  ́

15 52

31

COLOR CODES BASED ON TOTAL CONCENTRATION

1-3 TENTHS

LESS THEN

1 TENTH

ICE FREE

9-10 TENTHS

7-8 TENTHS

4-6 TENTHS

UNDEFINED

ICE

ICE SHELF

FAST ICE

(TEN TENTHS)

ICE ANALYSIS

Chukchi Sea

NATIONAL/NAVAL ICE CENTER

Analysis Week 11 Nov 2010

Data Sources Date

RADARSAT...........10 Nov

ENVISAT/GMM........10 Nov

Analysts: Szorc, Chris (NAVY CIV)

UNCLASSIFIED

CM = THEORETICAL ICE THICKNESS IN CENTIMETERS

 ́

NM = 168HR ANAL DRIFT VECTORS IN NAUTICAL MILES

IF = ICE FREE

A 1-3

1 1

3 1

3 X

B 3-5

3 1

3 1

3 X

C 3-5

1

X

D 5-7

2 4

3 1

3 X

E 5-7

4 2

3 1

3 X

F 5-7

1

X

G 7-9

3 5

3 1

3 X

H 7-9

5 3

3 1

3 X

I 7-9

6 2

3 1

3 X

J 7-9

6 2

3 1

K 7-9

3

3

L 9+

1 8

7 3

3 3

M 9+

1 6 2

9● 7 3

N 9+

2 4 3

9● 7 3

O 9+

3 6

7 3

P 9+

5 4

7 3

Q 9+

6 3

3 1

3 X

R 9+

6 3

3 1

S 9+

7 2

3 1

3 X

T 9+

3

3

U 10

1 9

7 3

8

V 10

2 8

7 3

8

W 10

3

8
A

C

D

E

F

G

H

I

I

I

M

N

Q

Q

R

T

T

T

T

T

T

T

T

T

T

V

T

U

S

O

L

J

D

I C

I G

K

B

T

D

P

O

IF

C

C

155°W 150°W 145°W

160°W

160°W

165°W

165°W

170°W

170°W

175°W

175°W

180°

170°E 175°E 180°

75°N

75°N

70°N

70°N

65°N

65°N

 ́

 ́

 ́

 ́

 ́

50

28

27

27

18

09

22

30

14

ICE

EDGE

COLOR CODES BASED ON TOTAL CONCENTRATION

1-3 TENTHS

LESS THEN

1 TENTH

ICE FREE

9-10 TENTHS

7-8 TENTHS

4-6 TENTHS

UNDEFINED

ICE

ICE SHELF

FAST ICE

(TEN TENTHS)

ICE ANALYSIS

Chukchi Sea

NATIONAL/NAVAL ICE CENTER

Analysis Week 15 - 19 Nov 2010

Data Sources Date

ALOS...............14 Nov

RADARSAT...........15 Nov

ENVISAT............15 Nov

Analysts: Szorc, Chris (NAVY CIV)

UNCLASSIFIED

CM = THEORETICAL ICE THICKNESS IN CENTIMETERS

 ́

NM = 168HR ANAL DRIFT VECTORS IN NAUTICAL MILES

IF = ICE FREE

A 1-3

1

X

B 3-5

2 2

3 1

3 X

C 3-5

3 1

3 1

3 X

D 3-5

1

X

E 3-5

1

F 5-7

1 5

3 1

3 X

G 5-7

3 3

3 1

3 X

H 5-7

1

X

I 7-9

6 2

3 1

3 X

J 7-9

1

X

K 9+

1 8

7 3

3 3

L 9+

1 7 1

9● 7 3

M 9+

2 7

7 3

3 3

N 9+

2 5 2

9● 7 3

O 9+

4 5

7 3

3 3

P 9+

6 3

7 3

Q 9+

7 2

3 1

3 X

R 9+

7 2

3 1

S 9+

8 1

3 1

3 X

T 10

1 9

7 3

8

U 10

2 8

7 3

8

V 10

3 7

7 3

8
National Ice Center

| Home | Products | IMS | Outside Links | Special Support | Full-Featured Page | 

Announcements | 

ICE CHART SYMBOLOGY 

The World Meteorology Organization (WMO) system for sea ice symbology is more frequently 

referred to as the "Egg Code" due to the oval shape of the symbol. 

So Sd

Ct - Total concentration of ice in area, 

reported in tenths. May be expressed as a 

single number or as a range, not to exceed 

two tenths (3-5, 5-7 etc.) 

Ca Cb Cc

 - Partial concentration (Ca, Cb, 

Cc) are reported in tenths, as a single digit. 

These are reported in order of decreasing 

thickness. Ca is the concentration of the 

thickest ice and Cc is the concentration of 

the thinnest ice. 

Sa Sb Sc - Stages of development (Sa, Sb, Sc) 

are listed using the code shown in Table 1 

below, in decreasing order of thickness. 

(NOTE: If there is a dot (.), all stages of 

development codes to the left of the dot (.) 

are assumed to carry the dot (.)) These codes 

correspond directly with the partial 

concentrations above. Ca is the concentration 

of stage Sa

, Cb is the concentration of stage 

Sb, and Cc

 is the concentration of Sc. 

So Sd - Development stage (age) of 

remaining ice types. So if reported is a trace 

of ice type thicker/older than Sa

. Sd is a 

thinner ice type which is reported when there 

are four or more ice thickness types. 

Fa Fb Fc

 - Predominant form of ice (floe 

size) corresponding to Sa

, Sb and Sc

respectively. Table 2 below shows the codes 

used to express this information. 

The Egg Code Page 1 of 3

http://www.natice.noaa.gov/products/egg_code.html 9/12/2011
Table 1. Egg Codes for Stages of Ice Development (Sx Codes)

Stage of Development 

for Sea Ice

Code

Figure

Stage of Development 

for Fresh Water Ice

New Ice-Frazil, Grease, Slush, Shuga (0-10 cm) 1 New Ice (0 - 5 cm) 

Nilas, Ice Rind (0 - 10 cm) 2 

Young (10 - 30 cm) 3 

Gray (10 - 15 cm) 4 Thin Ice (5 - 15 cm) 

Gray - White (15 - 30 cm) 5 Medium Ice (15 - 30 cm) 

First Year (30 - 200 cm) 6 

First Year Thin (30 - 70 cm) 7 Thick Ice (30 - 70 cm) 

First Year Thin - First Stage (30 - 70 cm) 8 First Stage Thick Ice (30 - 50 cm) 

First Year Thin - Second Stage (30 - 70 cm) 9 Second Stage Thick Ice (50 - 70 cm) 

Medium First Year (70 - 120 cm) 1. Very Thick Ice (70 - 120 cm) 

Thick First Year (>120 cm) 4. 

Old - Survived at least one season's melt (>2 m) 7. 

Second Year (>2 m) 8. 

Multi-Year (>2 m) 9. 

Ice of Land Origin 

Table 2. Egg Codes for Forms of Ice (Fx Codes)

Forms of Sea Ice Code 

Figure Forms of Fresh Water Ice

 ~F Belts and Strips symbol 

followed by ice concentration 

New Ice (0-10 cm) X 

Pancake Ice (30 cm - 3 m) 0 

Brash Ice (< 2m) 1 

Ice Cake (3 - 20 m) 2 

Small Ice Floe (20 - 100 m) 3 

Medium Ice Floe (100 - 500 m) 4 

Big Ice Floe (500 m - 2 km) 5 

Vast Ice Floe (2 - 10 km) 6 

Giant Ice Floe (> 10 km) 7 

Fast Ice 8 Fast Ice 

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Ice of Land Origin 9 

Undetermined or Unknown 

(Iceberg, Growlers, Bergy Bits) / 

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