U. S. National Ice Center
WMO SIGRID

WORLD METEOROLOGICAL ORGANIZATION (WMO)
GRIDDED SIGRID FORMAT FOR SEA ICE

The following identifiers are defined: Concentration
Stage of Development
Form of Ice

According to the new international system of sea-ice symbols, seven cases need to be distinguished
CT Total concentration, CC (code table 1)
CA Partial concentration, stage of development and form of thickest ice CaCaSaSaFaFa (code tables 1, 2 and 3)
CB Partial concentration, stage of development and form of second thickest ice CbCbSbSbFbFb (code tables 1, 2 and 3)
CC Partial concentration, stage of development and form of third thickest ice CcCcScScFcFc (code tables 1, 2 and 3)
CF Predominant FpFp and secondary FsFs form of ice (code table 3)
CN Stage of development of ice thicker than reported by SaSa but with a concentration less than 1/10, SoSo (code table 2)
CD Stage of development of any remaining class of ice SdSd not reported under CA, CB or CC (code table 2) (Note that no concentration or form of ice is reported for SoSo and SdSd).


Coding CTCC CACaCaSaSaFaFa CBCbCbSbSbFbFb CCCcCcScScFcFc (CFFpFpFsFs) CNSoSo CDSdSd
Fully Utilized Egg Code 4-6/211/7./4.1.7/1/~9
CC/CaCbCc/So/SaSbSc/Sd/FpFp
Graphical Egg Code Graphical display of the egg code.
SIGRID CT46CA209399CB109199CC108799CF1999CN95CD81


LIST OF VARIABLE IDENTIFIERS AND VARIABLES
Variable
Identifier		 Variable(s) Number of
Variables		 Digits
per
Variable		 Total
Number
of Digits
CT CC 1 2 2
CA CaCaSaSaFaFa 3 2 6
CB CbCbSbSbFbFb 3 2 6
CC CcCcScScFcFc 3 2 6
CF FpFpFsFs 2 2 4
CN SoSo 1 2 2
CD SdSd 1 2 2


LIST OF SEA-ICE VARIABLES
CC Total concentration of all ice in the area, reported in tenths (code table 1)
CaCa
CbCb
CcCc		 Partial concentration of respectively thickest, second thickest and third thickest ice reported in tenths (code table 1)
FaFa
FbFb
FcFc		 Form of ice corresponding to SaSa, SbSb, and ScSc respectively (code table 3)
FpFp
FsFs		 Predominant (FpFp) and secondary (FsFs) form of ice (code table 3)
SaSa
SbSb
ScSc		 Stage of development of respectively thickest, second thickest and third thickest ice of which the concentration is reported CaCa, CbCb and CcCc respectively (code table 2)
SdSd Stage of development of any remaining class of ice not reported by SaSa, SbSb, ScSc or SoSo (code table 2)
SoSo Stage of development of ice thicker than SaSa but with a concentration less than 1/10 (code table 2)

Code Tables

Code Table 1
Concentration (CC, CaCa, CbCb, CcCc) 		Code Table 2
Thickness of Ice or Stage of Development
(SaSa, SbSb, ScSc, SdSd, SoSo) 		Code Table 3
Form of Ice (FaFa, FbFb, FcFc, FpFp, FsFs)
Definition Code
Figure		 Stage of Development Thickness Code
Figure		 Form Size or Concentration Code
Figure
Ice Free 00 Ice Free   00 Pancake Ice 30 cm – 3 m 00
Less than 1/10
(open water)		 01 No Stage of Development   80 Shuga/Small Ice Cake,
Brash Ice		 < 2 m across 01
Bergy Water 02 New Ice   81 Ice Cake < 20 m across 02
1/10 10 Nilas, Ice Rind < 10 cm 82 Small Floe 20 m – 100 m across 03
2/10 20 Young Ice 1 – 30 cm 83 Medium Floe 100 m – 500 m across 04
3/10 30 Grey Ice 10 – 15 cm 84 Big Floe 500 m – 2 km across 05
4/10 40 Grey – White Ice 15 – 30 cm 85 Vast Floe 2 km – 10 km across 06
5/10 50 First Year Ice 30 – 200 cm 86 Giant Floe > 10 km across 07
6/10 60 Thin First Year Ice 30 – 70 cm 87 Fast Ice   08
7/10 70 Thin First Year Stage 1 30 – 50 cm 88 Growlers, Floebergs, or Floebits   09
8/10 80 Thin First Year Stage 2 50 &ndash 70 cm 89 Icebergs   10
9/10 90 For Later Use   90 Strips and Patches concentrations 1/10 11
More than 9/10
Less than 10/10		 91 Medium First Year Ice 70 – 120 cm 91 Strips and Patches concentrations 2/10 12
10/10 92 For Later Use   92 Strips and Patches concentrations 3/10 13
    Thick First Year Ice > 120 cm 93 Strips and Patches concentrations 4/10 14
Concentration
Intervals		 ClCh For Later Use   94 Strips and Patches concentrations 5/10 15
(Cl = Lowest
concentration in
interval)		   Old Ice   95 Strips and Patches concentrations 6/10 16
(Ch = Highest
concentration in
interval)		   Second Year Ice   96 Strips and Patches concentrations 7/10 17
Examples   Multi-Year Ice   97 Strips and Patches concentrations 8/10 18
1/10 – 3/10 13 Glacier Ice   98 Strips and Patches concentrations 9/10 19
4/10 – 6/10 46 Undetermined/Unknown   99 Strips and Patches concentrations 10/10 20
7/10 – 9/10 79       Level Ice   21
9/10 – 10/10 91       Undetermined/Unknown   99
Unknown 99            



Back to FAQ Page