Presentation on theme: "Ice Chart Colour Standard Proposal Approved by the JCOMM Sea Ice Expert Team October 21-25, 2002 John Falkingham on behalf of the IICWG Colour Code Working."— Presentation transcript:
Ice Chart Colour Standard Proposal Approved by the JCOMM Sea Ice Expert Team October 21-25, 2002 John Falkingham on behalf of the IICWG Colour Code Working Sub-Group
Ice Chart Colour Standard IICWG-2 (Oct 2000) started with initial ideas and principles IICWG-3 (Nov 2001) drafted the basis for this agreement refinements based on comments from Ice Services who tested the original proposal during the first half of 2002
Ice Chart Colour Standard Two separate colour codes for use on ice charts –one based on total concentration intended for use when the stage of development is relatively uniform but concentration is highly variable arctic summer navigation –one based on stage of development intended for use when the concentration is relatively uniform (high) but the stage of development is variable arctic winter navigation
Concentration Colour Standard Colour is based on Total Ice Concentration 7-10 tenths New Ice 255-175-255 9+-10 tenths Nilas, Grey Ice (mainly on leads) 255-100-255 Optional Areas of No Information are annotated accordingly <1 tenth ice 150-200-255 1-3 tenths ice 140-255-160 4-6 tenths ice 255-255-000 7-8 tenths ice 255-125-007 Shelf Ice 210-210-210 9-10 tenths ice 255-000-000 Ice Free 000-100-255 or Fast Ice 150-150-150 000-000-000 Undefined Ice ? ?
Stage of Development Colour Standard Areas of No Information are annotated accordingly Colour is based on Stage of Development of Predominant Ice Fast ice 150-150-150 220-080-235 170-040-240 New Ice Dark Nilas Light nilas Young ice Grey ice Grey-white ice FY thin ice FY thin ice (30 -50 cm) FY thin ice (50-70 cm) FY medium ice FY thick ice Old ice Second-year ice Multi-year ice Ice Free (amend: Free of Sea Ice) 150-200-255 * 000-000-255 255-175-255 * 255-100-255 * 135-060-215 155-210-000 215-250-130 175-250-000 000-200-020 000-120-000 180-100-050 * 255-120-010 200-000-000 or Shelf ice 210-210-210 000-000-000 Undefined Ice ? ?
Ice Chart Colour Code - Notes The two separate colour codes are mutually exclusive - only one or the other should be used on a single chart A legend depicting the colour code used should be included on every chart The optional colour indicating 9+-10 tenths of nilas or grey ice should only be used to indicate level ice, mainly on leads; it should not be used for ice broken into brash or ice cakes or for concentrations less than 9+ tenths Undefined ice is used when it is known that ice is in an area but its characteristics are not known - this is different from No Information which indicates that nothing at all is known about the area No specific colour is assigned to areas of “No Information”; such areas should be clearly indicated on ice charts - text annotation may be used where appropriate; an assigned colour within the code should not be used to indicate “No Information” Colour codes do not preclude use of black and white hatching patterns or egg codes; egg codes may be used along with with colours Other symbols may be used in addition to the standard colours to depict special ice conditions under national practice