4

Sy,  A.  et  al.  (2002):  Upper  Ocean  Climate  Ship-of-Opportunity  Programme  of  BSH  -  A  Status  Report

1.  Overview  of  upper  ocean  climate  monitoring  activities
The  ship-of-opportunity  programme  (SOOP)  managed  by  "Bundesamt  fur  Seeschifffahrt  und
Hydrographie"  (BSH)  focuses  on  the  North  Atlantic  Ocean,  and  on  the  North  and  Baltic  Seas.  Its
main  contribution,  the  Atlantic  XBT  programme  along  the  TOGA-WOCE-IGOSS  (TWI)  lines
AX-3  and  AX-11,  which  was  originally  planned  in  the  late  80s  as  a  contribution  to  WOCE  (World
Ocean  Circulation  Experiment)  and  IGOSS  (Integrated  Global  Ocean  Services  System,  now
JCOMM)  (Sy  and  Ulrich,  1989;  Sy  1993a),  has  been  continued  and  developed.  Almost  15,000
temperature  profiles  from  expendable  bathythermographs  (XBT)  have  been  obtained  so  far
covering  the  Atlantic  Ocean  from  the  North  Pole  to  the  Equator.  Within  the  framework  of  BSH’s
SOOP,  research  and  merchant  vessels  equipped  with  thermosalinographs  or  contact
thermometers  participate  in  near-surface  temperature  and  salinity  measurements.
The  thermohaline  circulation  (THC)  of  the  North  Atlantic  is  subject  to  strong  natural  variability  on
time  scales  ranging  from  years  to  decades  which  are  correlated  somehow  with  the  atmospheric
North  Atlantic  Oscillation  (NAO)  (e.g.  Dickson  et  al.,  1996;  Sy  et  al.,  1997a;  Koltermann  et  al.,
1999;  Curry  and  McCartney,  2001)  and  thus  influence  European  climate.  In  particular
occurrences  of  rapid  and  sustained  THC  changes  severely  affect  the  European  climate,  as  has
been  shown  by  palaeo-climate  records  and  model  studies  (e.g.  Dansgaard  et  al.,  1993;
Rahmsdorf,  1994;  1995;  Manabe  and  Stouffer,  1994;  1995;  IPCC,  2001).  Therefore,  and
because  all  observations  indicate  that  global  warming  is  continuing  (IPCC,  2001),  the  risk  of
such  changes  must  be  better  assessed.  However,  this  is  hampered  by  lack  of  observation  data.
For  that  reason,  BSH's  plans  to  upgrade  its  commercial  vessel-based  upper  ocean  thermal
programme  to  an  enlarged  upper  ocean  climate  programme  (in  particular  TWI  line  AX-3)  by
using  more  sophisticated  measurements  were  translated  into  action  in  1998.  As  a  contribution
to  GOOS  (Global  Ocean  Observing  System)  and  CLIVAR  (Climate  Variability  and
Predictability),  BSH  combined  the  AX-3  XBT  programme  with  occasional  XCTD  measurements
and  with  repeats  of  research  vessel-based  full-depth  hydrographic  sections  in  order  to  operate  a
well  designed  and  cost-effective  climate  related  monitoring  programme  in  the  GOOS  A2-corridor
  of  the  North  Atlantic  (BSH,  1999),  a  key  region  for  both  ocean  climate  and  European
climate  change  investigation.
As  BSH  acts  as  the  German  input  and  output  GTS  hub  for  real-time  oceanographic  data,  all
SOOP  data  are  inserted  as  BATHY,  TESAC  or  TRACKOB  coded  bulletins  onto  GTS  (Global
Telecommunication  System  of  WMO)  with  a  delay  of  about  1  day  to  1  week.  Real-time  data
from  various  Atlantic  ocean  areas  have  been  contributed  by  the  German  Navy  which  accounted
for  some  20  %  of  a  total  of  more  than  15,000  German  BATHY  data  circulating  on  the  GTS  in
2000  and  2001,  respectively.  Since  2001,  however,  the  Navy’s  data  contribution  has  decreased
almost  to  zero  due  to  changes  in  its  declassifying  policy.  Further  BATHY  data  are  contributed  in
real-time  by  BSH's  stationary  "Marine  Environmental  Monitoring  Network  in  the  North  and  Baltic
Seas"  (MARNET).
The  scientific  rationale,  current  technical  and  organizational  status,  and  some  preliminary  results
of  the  operational  programme  and  other  related  operational  data  activities  are  described  briefly
in  this  report.