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.  Click on portions of the egg for additional information.

S_o

S_d

C_t  -  Total concentration of ice in area, reported in tenths.
Concentration may be expressed as a single number or as a range, not to exceed two tenths (3-5, 5-7 etc.)

C_a C_b C_c  -  Partial concentration (C_a, C_b, C_c) are reported in tenths, but must be reported as a single digit.  These are reported in order of decreasing thickness.  C_a is the concentration of the thickest ice and C_c is the concentration of the thinnest ice.

S_a S_b S_c  -  Stages of development ( S_a, S_b, S_c) are listed using the following code in decreasing order of thickness.  (NOTE: If there is a dot (.), all stage of development codes to the left of the dot (.) are assumed to carry the dot (.)) These codes are directly correlated with the partial concentrations above.  C_a is the concentration of stage S_a, C_b is the concentration of stage S_b, and C_c is the concentration of S_c.   (Table 1)

F_a F_b F_c  -  Predominant form of ice (floe size) corresponding to S_a, S_b and S_c respectively.  (Table 2)

S_o S_d  -  Development stage (age) of remaining ice types.  So if reported is a trace of ice type thicker/older than S_a.  S_d is a thinner ice type which is reported when there are four or more ice thickness types.