68

Characteristics  of  the  1999/2000  ice  season  in  the  Szczecin  Lagoon  and  Pomeranian  Bay
The  1999/2000  ice  season  in  the  coastal  waters  of  Mecklenburg-Vorpommern  was  very  short.
In  the  first  frost  period,  first  ice  formed  only  in  Karnin  during  three  days  from  23  December  (Figure
6.3).  In  all  other  areas  of  Szczecin  Lagoon,  first  ice  did  not  form  until  the  third  frost  period  in  the  second ­
  decade  of  January.  Thin  ice  covered  the  near-shore  areas,  reaching  4  to  6  cm  thickness  by  26
January  (Figure  6.2).  In  the  harbours  and  in  the  Szczecin  -  Swinoujscie  navigation  channel,  very  open
to  open  ice  up  to  5  cm  thickness  was  observed  on  three  to  six  days  during  this  period.  The  Pomeranian ­
  Bay  remained  completely  ice-free.
On  30  January,  the  whole  area  of  Szczecin  Lagoon  was  reported  to  be  ice-free.
In  the  winter  of  1999/2000,  the  ice  cover  in  the  area  of  Szczecin  Lagoon  lasted  from  3  to  8  days.
During  the  time  of  ice  formation,  navigation  in  the  inner  parts  of  the  Szczecin  Lagoon  was  difficult  for
small  and  low-powered  vessels,  but  otherwise  the  central  part  of  the  Szczecin  Lagoon  was  nearly  free
of  ice  and  easy  to  navigate  during  the  whole  ice  season  1999/2000.

Trends  of  Ice  Conditions  in  the  Szczecin  Lagoon  in  the  period  1929-2000
The  development  of  ice  conditions  in  the  Szczecin  Lagoon  is  analysed  on  the  basis  of  the  data  reported ­
  by  the  Ueckermiinde  station,  which  is  located  on  the  southern  shore  of  Kleines  Haff.  The  observation ­
  period  starts  in  the  winter  of  1928/29  and  covers  the  complete  period  up  to  the  present,  with
only  the  winters  of  1944/45  and  1945/46  missing.  The  data  on  the  beginning  and  end  of  ice  occurrence ­
  and  on  the  number  of  days  with  ice  up  to  winter  1946/47  are  given  in  (Bliithgen,  1954).

Table  6.2.  Statistics  of  the  ice  parameters  (only  for  winters  with  ice)
Station:  Ueckermiinde,  Szczecin  Lagoon
Period  of  observations:  1928/29  -  1999/2000  (no  data  from  the  winters  44/45,  45/46)

Number  of  observed  winters

70

Number  of  winters  with  ice

68

Number  of  winters  without  ice

2

Calculations

Beginning  of  ice  formation

End  of  ice  occurrence

(only  for  winters  with  ice)

earliest

median

latest

earliest

median

latest

13.11.

18  Dec

23.02.

06.12.

9  March

21.04.

(1940/41)

(1943/44)

(1988/89)

(1995/96)

St.  deviation

±22

±29

Calculations

Number  of  days  with  ice

Max.  ice  thickness  in  cm

since  46/47)

(only  for  winters  with  ice)

min

mean

max.

min

mean

max.

3

58

141

1

20

50

(1995/96)

(1946/47)

St.  deviation

±36

±  13

The  data  for  all  winters  since  1946/47  have  been  taken  from  the  observation  records,  which  made  it
possible  to  include  the  ice  thickness  measurement  data  in  the  study.  Table  6.2  shows  the  median  and
extreme  ice  parameters  for  the  70-year  period,  considering  only  winters  with  ice.  In  the  very  mild  winters
of  1973/74  and  1974/75,  no  ice  formation  occurred  in  the  Kleines  Haff  area,  where  the  relative  frequency
of  ice  occurrence  normally  is  very  high,  at  97%.