Analysis  of  the  Ice  Model  Simulation  for  the  Gulf  of  Finland  In  2002/2003

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Ice  conditions
The  ice  season  of  2002/03  started  with  rapid  ice  formation.  In  the  early  November  2002  ice
cover  begin  to  develop  in  the  Bothnian  Bay  and  in  the  Gulf  of  Finland.  At  the  end  of  December
the  whole  Gulf  of  Finland  was  covered  by  the  ice,  ice  thickness  was  from  15  cm  in  west  to  50
cm  in  east  (Pastukhov  2003).
The  maximum  thickness  of  fast  ice  from  70  to  90  cm  in  the  north  of  Bothnian  Bay,  60  to  75  cm
in  the  Sea  of  Bothnia,  50  to  65  cm  in  the  western  Gulf  of  Finland  and  65  to  80  cm  in  the
eastern  Gulf  of  Finland.  The  maximum  ice  thickness  in  open  sea  was  40  to  60  cm  in  the  Bay  of
Bothnia,  20  to  40  cm  in  the  Sea  of  Bothnia,  5  to  20  cm  in  the  northern  Baltic  Sea  and  40  to  75
cm  in  the  Gulf  of  Finland.  The  ice  season  lasted  over  one  month  longer  than  on  the  long-term
average  in  the  Gulf  of  Finland  and  about  two  weeks  longer  in  the  Bothnian  Bay  (FIMR,  2003).
In  2003  was  ice  very  thick  and  deformated,  navigation  was  difficult  and  restrictions  valid  11T-149
  days  (Seina  2003)  If  the  ice  breaking  was  usually  needed  since  January  then  2003  year
was  different,  icebreakers  were  needed  already  since  December.  And  maximum  extent  of  ice
was  achieved  in  Gulf  of  Finland  on  5  of  March  with  232000  km 2 .
Vessels  needed  already  in  January  to  navigate  through  the  ice  for  the  longest  way  in  40  years.
Sailing  distance  reached  up  to  200  nautical  miles,  average  distance  is  about  50  nautical  miles.
The  season  2002/03  was  classificated  as  an  average  season  in  Baltic  sea  but  severe  ice
thickness  in  Golf  of  Finland.  (Seina  2003).
Results
The  total  ice  extent  during  the  winter  2002/03  was  already  very  large  since  at  the  beginning  of
January.  On  16 th  of  January  total  ice  concentration  decreases  quickly  from  100%  to  70  %
mains  due  to  ice  deformation  (Fig  3).  The  ice  deformed  at  sharply  growing  rate  this  time.  Time
series  of  simulated  mean  total  ice  concentration  is  in  good  agreement  with  observed  data.  We
see  the  deformed  ice  concentration  increasing  at  the  fig.  4  between  longitude  23.7-25E  and
27.5-28E.  We  see  in  fig.  5,  mean  total  ice  thickness  increase  at  the  Estonian  coast.  Wind
speed  over  8  m/s  blew  to  NE  induce  ice  deformation  at  the  south  and  east  coast.