OPUS  II:

About  4  and  a  half  years  later  the  BSH  and  the  Institut  für  Ostseeforschung  Warnemünde
(IOW,  Baltic  Research  Institut  Warnemünde)  carried  out  a  second  joint  experiment  -  OPUS  II  -
from  May  to  June,  1998.  At  four  positions  the  BSH  deployed  bottom-mounted  300  kHz
Workhorse  ADCPs  (BSH1,  2,  3,  and  4,  see  Fig.  1).  A  current  meter  mooring  with  two  Aanderaa
RCM  7  current  meters  was  deployed  at  station  BSH5.  The  IOW  deployed  two  600  kHz  bottommounted
  BroadBand  ADCPs  (RD  Instruments)  at  positions  IOW1  and  2.  The  ADCP  at  position
BSH3  failed  after  about  10  hours  due  to  leakage  (see  Table  "Moorig  Data  OPUS  IF’)  The  record
length  is  11  days  for  the  IOW-moorings  and  35  or  36  days  for  the  BSH-moorings.  All  instruments
had  a  sampling  interval  of  10  minutes.  Again,  the  data  will  be  used  to  test  and  validate  numerical
circulation  models  which  are  run  both  by  the  BSH  and  IOW.  In  contrast  to  the  winter  survey
during  OPUS  I,  the  OPUS  II  data  represent  a  current  pattern  at  the  beginning  of  the  summer.
Compared  to  earlier  investigations  of  current  measurements  in  the  western  Baltic  by  Lange,
Mittelstaedt  and  Klein  [1991] 1  2 ,  OPUS  I  and  II  represent  synoptical  data  sets  which  allow  the
reconstruction  of  circulation  patters  in  the  Mecklenburg  Bight.  Therefore,  for  both,  OPUS  I  and
OPUS  n,  time  series  of  the  meteorological  parameter  wind  speed,  wind  direction  and  air  pressure
are  shown  for  the  stations  Puttgarden  (Fehmarn),  Boltenhagen,  and  Warnemünde.  For  better
comparison  with  the  current  data,  the  wind  direction  is  given  in  the  oceanographic  sense,  i.e.,  it  is
the  direction  in  which  the  wind  blows.  Also  given  is  a  percentage  frequency  distribution  for  wind
speed  and  direction.
FBB  1995:
Between  OPUS  I  and  II  the  BSH  measured  the  current  at  the  Fehmambelt  Buoy  (FBB)
continuously  from  April,  1995  until  January,  1996.  This  site  is  a  key  position,  because  the
Fehmambelt  is  the  main  passage  for  the  inflow  of  dense  oxygene-rich  bottom  water  from  the  North
Sea  into  the  Baltic  proper.
Whereas  from  July,  13  until  August,  8  the  BSH  maintained  a  current  meter  mooring  with
two  RCM7  current  meters  at  8  m  and  25  m  depth,  during  the  rest  of  the  time  a  300  kHz
Narrowband  ADCP  or  a  600  kHz  BroadBand  ADCPs  has  been  used.  Both  instruments  were
1  Wolfgang  Lange,  Ekkehard  Mittelstaedt,  Holger  Klein,  1991:
Strömungsdaten  aus  der  Westlichen  Ostsee.  Meßergebnisse  aus  dem  Zeitraum
1982  bis  1986  sowie  historische  Beobachtungen  vom  Feuerschiff  „Fehmarnbelt". ­
  Dt.  hydrogr.  Z.,  Reihe  B,  Nr.24.
2