The roots of the Baltic Sea Ice Meetings (BSIM) 1925-1938

BALTIC SEA ICE MEETINGS (BSIM) since 1954

Ice observations and their coding

The development of the Baltic Sea Ice Code of 1980; a code for reporting ice and navigational conditions

Overview

By the end of the 19th century, the national ice services of several countries bordering the North and Baltic Seas had introduced routine ice observing and reporting systems. The search for a suitable ice reporting code began very early because a quick and convenient way of transmitting the ice observations to a central body and making them available to users was urgently needed. Shipping traditionally has a large variety of terms designating the different ice phenomena, taking into account regional differences that are attributable to different natural environments. Although today an essential criterion in the assessment of ice conditions still is the extent to which they hinder navigation, additional features describing the ice extent had to be introduced within the framework of the international exchange of ice information required in the wake of World War I. Requests for more and better ice information on the part of industry and shipping, efforts within the World Meteorological Organization to develop a uniform terminology, the transition to a prolonged shipping season lasting throughout winter in the Gulfs of Bothnia and Finland as well as increasing activities in the coastal areas forced the ice services to continually improve the technology and contents of their information exchange.

The chronological order (of Baltic Sea Ice Code, Ice Observing Stations and WMO Sea Ice Nomenclature / Ice Symbols) can be summarized as follows:

• 1920/21 National ice code
  • 1st digit: ice conditions
  • 2nd digit: impact on navigation
• 1928/29 1st Baltic Sea Ice Code
  • 1st digit: ice conditions
  • 2nd digit: navigation
• 1952 1st WMO Sea Ice Nomenclature
• 1954/55 2nd Baltic Sea Ice Code (revised in 1969, GTS use)
  • 1st digit: (i): ice conditions
  • 2nd digit (j): stage of ice development
  • 3rd digit (k): navigational conditions
• 1968 2nd WMO Sea Ice Nomenclature
• 1980 WMO Ice Symbols
• 1981/82 3rd Baltic Sea Ice Code of 1980 (B = Baltic)
  • 1st digit (AB) = quantity and arrangement of ice
  • 2nd digit (SB) = stage of ice development
  • 3rd digit (TB) = topography and form of ice
  • 4th digit (KB) = navigational conditions
• 1955/56, 1981/82, 1993/94 Change of German station numbers

Baltic Sea Ice Code of 1980

This code is still in use nowadays and describes the ice conditions in harbours, fairways, coastal areas, and marked navigation channels. Together with the ice charts and detailed written ice reports, it informs ships' officers of current ice and navigational conditions. The sea and navigation districts of each country are designated by letters: AA, BB, CC etc. Each district is subdivided into sections numbered from 1 to 9.

The single observations for the code elements
AB, SB, TB, KB thus are compiled and distributed in the following general code format:

AA   1AB, SB, TB, KB   2AB, SB, TB, KB   3AB, SB, TB, KB....   nAB, SB, TB, KB 
BB   1AB, SB, TB, KB   2AB, SB, TB, KB   3AB, SB, TB, KB....   nAB, SB, TB, KB 

The fairway districts (AA, BB, ...) in the individual countries are sorted regionally from north to south and east to west, and the fairway sections (1,... 2,...) from onshore (harbour) to offshore (sea). The code numbers AB, SB, TB, KB define the ice conditions in the respective section according to the code.