International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 3

Number 4

December 2009

415

1 ICE CONDITIONS IN THE BALTIC SEA

Baltic Sea is a semi-closed, tide less and compara-

tively dismembered sea. Its low salinity varies from

about 20 %

in the Belts waters to about 1%

in the north-eastern basins. The differentiation

of salinity, bathymetry, the latitudinal and continen-

tal (climatic) influences generates significant inho-

mogeneity of freezing conditions in different basins

of the sea. Some of the basins freeze each winter, the

other only rarely, during exceptionally severe win-

ters. In order to be able to compare the winter condi-

tions in different years or in different basins of the

sea, some scales of winter severity are in use. Ac-

cording to one of them (sea ice severity index S

reg

after Sztobryn et al.,2008) three types of winters

were distinguished (mild, normal and severe) and a

classification of winters between 1955 and 2005 in

the Baltic Sea was made, as in Table 1.

Highest values of sea ice index S

reg

were charac-

teristic for the Bay of Bothnia, where they oscillated

between 9,32 in 1980/81 and 5,34 in 1991/92. The

lowest values of S

reg

were gained in the Western

Baltic, with the minimum equal to 0,0, what oc-

curred for eight times in the investigated 50 winter

seasons, while the maximum value there was as high

as S

reg

5,72 in 1995/96. Quite close to the values

representative for the Western Baltic were the ex-

treme conditions in the Aland Sea and the Archipel-

ago: maximum value of S

reg

reached there 5,89 in

1969/70 and the minimum value was 0,0 (for four

times).

The values of basic S

reg

statistics, when com-

pared, allowed to distinguish three groups of regions

considered here, which were similar to each other

with regard to the sea ice conditions.

Table 1. Number of winters of given severity in particular basins of the Baltic Sea in the winter seasons 1955/56 – 2004/05 (Szt-

obryn et.al.2008)

__________________________________________________________________________________________________________

type of sea ice severity Baltic Western Southern Gulf Aland Sea Norra Bay

Baltic Baltic of Finland & Arch of Bothnia Kvarken of Bothnia

__________________________________________________________________________________________________________

mild 17 43 36 16 33 14 2 0

normal 17 1 8 11 9 11 4 0

severe 16 6 6 23 8 25 44 50

__________________________________________________________________________________________________________

Sea Ice Services in the Baltic Sea

M. Sztobryn

Institute of Meteorology and Water Management, Maritime Branch, Gdynia, Poland

ABSTRACT: The Baltic winter navigation depended always very much on the ice conditions in the sea. The

sea ice occurs different in form and amount, depending on the sea area and the winter season. As the maritime

traffic on the Baltic Sea constitutes a substantial amount in the whole of the Baltic countries transport, Sea Ice

Services (SISs) have come into being. They constituted the Baltic Sea Ice Meeting (BSIM) – a body, which

assembles the parties, which are interested in warnings against bad ice conditions, and in protection of naviga-

tion in ice in the Baltic Sea. An indispensable co-operator to this body was always the company “Baltic Ice-

breakers”. To-day within the BSIM operate by the SISs of Denmark, Sweden, Finland, Russia, Estonia, Lat-

via, Lithuania, Poland and Germany, Netherlands, Norway and the Baltic Icebreakers. The main statutory

duties of the SISs is the acquisition, processing and dissemination of actual information on sea ice conditions

and on obstructions to navigation due to sea ice. This is done by maintaining observing posts along the coast

of those countries, in their ports and approaches to them, by gathering information from ships, from ice beak-

ers, if possible – from reconnaissance flights or satellite images. Routine products of SISs are the ice reports,

ice bulletins, ice charts, forecasts and warnings and other information broadcast by mass media, e.g. radio,

internet, Navtex and on the national and Baltic SISs’ web sites etc.

416

The first group, the “mild winters zone”, consisted

of the Western Baltic Sea, Southern Baltic Sea and

the Aland Sea; the second group, the “normal win-

ters zone” made the western Gulf of Finland and the

Sea of Bothnia. Into the third group, the “severe

winters zone”, were included the Norra Kvarken and

the Bay of Bothnia, where the statistical parameters

of S

reg

were positively higher, than in the remaining

considered regions of the Baltic Sea. It must be

stressed that though very characteristic, the above

cited indices did not involve all areas of the Baltic

Sea, as for instance, the south-eastern coasts of the

central sea parts.

There exists a high proportionality between the

values of the indices S

reg

and the number of ice-

breaker assistances, requested by all kind of vessels

plying between the coasts of the Baltic Sea. The ice-

breakers are ready to assist any ship on the ice ob-

structed routes of the Baltic Sea, from the Belts to

the farthest ends of the Bothnia Bay or the Gulf of

Finland. Varied ice conditions in the Baltic Sea

cause much greater navigational difficulties in the

northern and eastern parts of the sea. One of the in-

dicators of those difficulties is the number of cases,

in which the assistance of icebreakers is indispensa-

ble. For instance, in the 50 years considered here,

the number of assistances of only the Swedish and

Finnish icebreakers varied from 121 in the winter

season 1991/92 to as many as 4107 during the winter

1986/87 (Grafstrom & Kiggren, 2007). The relation-

ship between the ice severity (by the severity indices

for Baltic Sea and Aland Sea) and icebreakers activ-

ities (number of cases, in which the Swedish and

Finnish icebreakers assisted the ships) is presented

by the comparison, of how these two winter features

varied during the 50 winters of 1956 – 2005 (Figure

1).

Figure 1. Long term icebreakers activity variation (in annual

number of assistance cases) compared to winter severity (rep-

resented by the sea ice severity indices) during the winters

1955/56 – 2004/2005.

The seasonal sea ice severity is presented by the

ice severity index S averaged over the whole Baltic

Sea and regional, and the ice breakers activity is

shown in number of cases, in which icebreakers as-

sisted the ships. It must be stressed here that the

BSIS are always supported by both the icebreakers

and the ship masters in gaining actual information

on ice conditions on their sea routes.

2 THE SCOPE OF ACTIVITIES AND

ORGANISATION OF THE BALTIC SEA ICE

SERVICES

The Baltic winter navigation depended always very

much on the ice conditions in the sea. The sea ice

occurs different in form and amount, depending on

the sea area and the winter season. As the maritime

traffic on the Baltic Sea constitutes a substantial

amount in the whole of the Baltic countries

transport, Sea Ice Services (SISs) have come into be-

ing. They constituted the Baltic Sea Ice Meeting

(BSIM) – a body, which assembles the parties,

which are interested in warnings against bad ice

conditions, and in protection of navigation in ice in

the Baltic Sea. An indispensable co-operator to this

body was always the company “Baltic Icebreakers”.

To-day within the BSIM operate by the SISs of

Denmark, Sweden, Finland, Russia, Estonia, Latvia,

Lithuania, Poland and Germany, Netherlands, Nor-

way and the Baltic Icebreakers (Fig.2). The main

statutory duties of the SISs is the acquisition, pro-

cessing and dissemination of actual information on

sea ice conditions and on obstructions to navigation

due to sea ice. The existence of BSIM and coopera-

tion between SISs guarantees the use of standard-

ised ice messages, codes, graphic symbols, formats,

etc in the ice data exchange not only between all

these countries but also for navigators.

Figure 2. Sea Ice Services in the Baltic Sea Ice Meeting.

BSIM as well as SISs is working on two levels –

the national one and the international.

The national level involves :

0,00

1,00

2,00

3,00

4,00

5,00

6,00

7,00

1955/56

1956/57

1957/58

1958/59

1959/60

1960/61

1961/62

1962/63

1963/64

1964/65

1965/66

1966/67

1967/68

1968/69

1969/70

1970/71

1971/72

1972/73

1973/74

1974/75

1975/76

1976/77

1977/78

1978/79

1979/80

1980/81

1981/82

1982/83

1983/84

1984/85

1985/86

1986/87

1987/88

1988/89

1989/90

1990/91

1991/92

1992/93

1993/94

1994/95

1995/96

1996/97

1997/98

1998/99

1999/00

2000/01

2001/02

2002/03

2003/04

2004/05

Sea ice severity index

500

1000

1500

2000

2500

3000

3500

4000

4500

icebreakers activity

Baltic Sea

Aland Sea and Archipelago

icebreakers activity

417

− network of coastal observing posts,

− data collecting centre,

− Sea Ice Service National Centre

The Sea Ice Service National Centre is responsi-

ble for :

− acquisition of all possible ice information (from

beyond the routine ice observing network data) as

icebreaker data, satellite data, air reconnaissance

data etc,

− data control and interpretation,

− edition and dissemination of ice information in

form of ice reports, ice bulletins, ice charts etc,

− forecasts of ice conditions development,

− exchange of ice information - locally, and in the

region - internationally,

− co-operation with icebreakers.

The international level demands for:

− daily routine exchange of ice information prod-

ucts between the Sea Ice Services,

− international co-operation with Ice Breaker Ser-

vice,

− participation in BSIM conferences in order to

asses the activities of the National Sea Ice Ser-

vices, to implement the developing technologies

into these activities and to adapt these activities

to changing economic and political conditions,

− co-operation with the WMO, JCCOM as well as

with International Ice Charting Working Group

(IICWG).

Between the BSIM conferences, the activities of

the Sea Ice Services are co-ordinated by the repre-

sentatives of the National SISs, under the leadership

of the acting BSIM Chairman.

3 SHORT HISTORY OF THE BALTIC SEA ICE

SERVICES

Importance of the winter navigation in the Baltic Sea

on one side and on the other – serious sea-ice borne

difficulties, forced in the regions of severe winters

regular sea ice observations already in the middle of

19-th century. This, however, was initiated by indi-

vidual countries (the economy of which mostly de-

pended on sea traffic, also in winter). Therefore the

first observations were carried out only in those

countries, with no integration on larger scale.

The tragedy of “Titanic” powered to create the

first in the world, a completely organised, world

wide sea ice service (International Ice Patrol). In this

time Europe began also to develop the protection of

winter traffic in sea ice conditions. However the

World War 1 and the following formation of new

political systems on the continent did not allow to

meet the Baltic ice experts earlier than in 1925

(Strubing 2003). That ensemble of experts on pro-

tection against sea ice discussed the in that time

available instruments of information exchange;

among others they proposed the use of the Baltic Sea

Ice Code (BSIC). Already in 1926, on the 1st Con-

ference of the Baltic Hydrographers (CBO) in Riga

the frames of data exchange standardisation had

been settled, and one year later, on the 2nd CBO, the

first BSIC was accepted. The recommendations of

this Conference were implemented very soon, and

already in the severe winter 1928/29 the majority of

information, among them the ice charts, was used

according to the uniform BSIC rules. In the year

1936, on the 5th CBO in Helsinki the status quo of

the SISs was discussed, including reports on their

organisation and activities. Also the sea ice termi-

nology was completed and accepted, together with

the multilingual terminology of the BSIC.

The World War 2 interrupted the co-operation

within the BSIM. The National SISs, however, re-

sumed their ice information exchange by the same

rules as before, straight away after the war ended.

Not earlier, however, than in the year 1954 the ice

experts of Denmark, Finland, Federal Republic of

Germany, the Netherlands and Sweden activated the

BSIM to compile the International Sea Ice Termi-

nology and to actualise the BSIC by enriching its

content. Short after 1956 also the former German

Democratic Republic, Poland and the former USSR

sent their representatives to resume the co-operation

within the BSIM. Further meetings of this body con-

sisted in improving the information exchange tech-

nologies, in the revision and actualisation of BSIC

and ice chart (among them the Sea Ice Egg Code), in

completing the multilingual vocabulary of sea ice

terminology, digitalisation of ice charts by introduc-

ing the SIGRID code and last, but not least, in im-

plementing the mathematical prognostic models of

ice conditions development into the operational rou-

tine. Successive years brought enormous develop-

ment in both observation technologies (remote sens-

ing, aircraft reconnaissance, radar and satellite

imagery) and in data transmission (internet, Navtex,

other mass etc). Successive BSIMs had to cope with

that abundance of potentiality to be implemented in-

to the Sea Ice Service observing practices, into data

transmission and forecasting. Sea ice codes had to be

repeatedly revised and completed, also due to politi-

cal changes in the last decade of the 20

century. In

the year 2005, on 21

BSIM in Riga the Memoran-

dum of Understanding of the Sea Ice Services has

been signed by the majority of the national services.

4 BALTIC SEA ICE CODE

This code is a set of conventional numeral symbols

used in transmitting messages on ice conditions and

obstruction to navigation due to sea ice in particular

418

areas of the Baltic Sea, in ports and approaches to

them and on other sea router (about 500 observa-

tional posts). After having collected all the ice mes-

sages from its region of responsibility, each individ-

ual SISs prepares national ice report/ice bulletins

(Fig.3) and transmits it to be broadcast by the Global

Telecommunication System (GTS). The first edition

(used as national code from 1920/21) of Baltic Sea

Ice Code (from 1928/29) contained only two groups,

specified as “j” and “k”. Under “j” described were

the ice conditions, under “k” – the obstruction to

navigation due to the ice. The second BSIC estab-

lished in 1954/55 (used in Poland from1963) and re-

vised in 1969, was modified by adding another

group on ice development. Now by “i” were meant

the ice conditions, by “j” – ice development, and by

“k” – impact on navigation by ice. The third BSIC

has been introduced in 1981 and is till to-day in use.

It described the ice conditions in ports, fairways and

significant navigation channels. BSIC (in ice bulle-

tins and reports) with ice charts give the detailed in-

formation for ships’ officers of actual ice and navi-

gation conditions. The sea and navigation areas of

each country are designated by capital letters AA,

BB, CC ets. Each area is subdivided into parts num-

bered from1 to 9. Baltic Sea Ice Code (Figure 3)

consists of four groups:

– amount and arrangements of sea ice,

– stage of ice development,

– topography or form of ice,

– navigation conditions in ice

Figure 3. An example of Polish Sea Ice Report from 12 of

Feb.2001

where CC18353 after decoding:

CC “1” = observational post; here Swinoujscie,

Pomerania Bay,

“8” – fast ice,

“3”- grey-white ice,

”5”-rafted ice,

”3”-navigation without icebreaker assistance

possible only highpowered vessels of strong

construction and suitable for navigation in ice.

The receivers of the ice reports from the whole

sea region use them, after having decoded them, to

compile their routine products: ice bulletins, ice

charts and other information, e.g. the forecasts. Ice

report/ ice bulletin is edited daily or weekly, depend-

ing on the severity of sea ice situation. Also ice bul-

letins, which give detailed ice situation in the whole

Baltic Sea area are issued routinely, in national lan-

guages and additionally in English. Bulletins can be

mailed in paper form or e-mailed to the users.

5 ICE CHARTS

Ice charts were one of the oldest methods to distrib-

ute the information on sea ice conditions and on the

obstructions, which the ice could be to navigation.

The first ice charts, which now are stored in ar-

chived form, were drawn already in the end of 19

century. As a routine product of the SISs, however,

they were issued not earlier than about the nineteen

thirties. The main aim of an Ice Chart is to project

on a map the actual ice conditions in the given sea

basin or route.

Figure 4. Polish Ice Chart from 8

of March 1929, issued by the

Maritime Branch of the Państwowy Instytut Meteorologiczny

in Gdynia.

Thus, an ice chart is a graphic supplement of the

ice information contained in the Ice Report/Ice Bul-

419

letin and is issued daily, when ice conditions are se-

vere, or twice a week, when the winter is calm.

The form, in which the ice conditions were pre-

sented on the ice charts, depended on the contempo-

rarily available presentation technologies and on the

accepted graphic symbols. Important also were the

ways by means of which the maps were distributed

to the users, especially ship masters, icebreakers,

port officers.

The oldest Polish archived Ice Chart is dated on

winter 1929 and is reproduced in Figure 4.

The chart was issued by the Wydział Morski in

Gdynia of the contemporary Państwowy Instytut

Meteorologiczny (Polish National Meteorological

Institute). Ice conditions were presented by numbers

of code in due chart places and the degree of ob-

structed navigation – by different colours. Beside of

the graphic presentation a general description of ice

conditions was given in plain language in Polish,

English and German. Additionally, a more detailed

description of ice situation in the Polish waters was

given, including information on air temperature and

wind. This, however, was a hand-made chart, deliv-

ered by messengers or mailed.

Figure 5. Polish Ice Chart from 13 of March 1987, edited by

Oddział Morski IMGW in Gdynia (Marine Branch of the

Institute of Meteorology and Water Management).

In the post-war decades, along with the telecom-

munication and other technical means development,

the appearance of ice charts changed. When the fac-

simile transmission got possible, ready ice charts, in

order to be transmitted to the addressees, had to be

monochrome. Therefore, since 1981, new principles

of one-colour drawing of ice charts were set. The

Polish Ice chart had a conform conic projection and

covered the area of the whole Baltic Sea, including

Kattegat. Further, it gave all indispensable infor-

mation on the ice conditions in the sea, the bays and

lagoons.

Additionally, thickness of ice was added and

names of icebreakers operating in particular sea are-

as could be inserted. However, preparation of an ice

chart in that way was laborious enough (Fig.5).

Figure 6. Ice chart of 12 of March 2004, issued by Oddział

Morski IMGW in Gdynia

Further enormous development of the telecom-

munication facilities, as satellite links, internet,

simplified both the transmission and preparation of

ice charts and allowed for a come-back of coloured

charts (Fig.6).

Similar ice charts are edited by the majority of

SISs, excluding Lithuania and Latvia. Russia reduc-

es the area of its Ice Chart to the Gulf of Finland on-

ly, Estonia to the Gulf of Finland and the Gulf of

Riga.

6 SUMMARY

The above discussed Baltic SISs’ products (ice mes-

sages, reports, bulletins, ice charts and forecasts) do

420

not involve the full list of sea ice information which

is collected, processed and disseminated by these

bodies. Merely mentioned were the ice development

and movement forecasts. Also the users were scarce-

ly mentioned, as the circle of users depends on indi-

vidual needs of given country’s national economy.

Once more the role of telecommunication must be

stressed. In previous ice seasons sea ice information

was broadcast by radio, routinely with weather fore-

casts. Since nineteen nineties it is available by

NAVTEX. Beside of this, the SISSs’ products are

published by internet – both on the web pages of the

particular SISSs’ as well as on the web of the BSISs.

The investigation was made under the IMGW pro-

jects DS-H7 and project PL0 103 “Strengthening of

the administrative capacity to improve management

of the Polish coastal zone environment”- Seaman fi-

nanced by the Norwegian Financial Mechanism.

REFERENCES

Jevrejeva S., Drabkin V.V., Kostjukov J., Lebedev A.A.,

Leppäranta M., Mironov Y.U., Schmelzer N., Sztobryn M.,

2002: Ice Time Series of the Baltic Sea, Report Series in

Geophysics No. 44, Helsinki,.

Grafstrom T.& Kiggren D.2007: A summary of the ice season

and icebreaking activieties 2006/2007, pp.54.

WMO 574, 2004: Sea-Ice Information Services in the World

Schmelzer N., Seina A., Lundqvist J.E., Sztobryn M., 2008,

Ice, in: State and Evolution of the Baltic Sea, 1952-2005,

Wiley & Sons, 199-240,

Strubing K. 2004 The roots of BSIM, www.bsh.de,

Sztobryn, M., 2006, Zlodzenie polskiej strefy przybrzeżnej w

latach 1955-2005, IMGW Report of DS.-H7 project