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1

Introduction

Operational  numerical  models  have  been  used  at  the  Bundesamt  für  Seeschifffahrt  und
Hydrographie  (BSH) 1  for  many  years  now  to  support  various  maritime  services  (Dick,
1997,  Huber,  1993).  "Operational"  means  that  the  models  are  used  for  daily  routine
simulations  of  the  North  Sea  and  Baltic  Sea  dynamics,  i.e.  currents,  temperature,  salinity,
dispersion  of  substances  etc.  Although  the  model  system  had  been  designed  primarily  as
a  tool  for  several  BSH  services,  the  simulation  data  have  also  been  used  in  oceanographic ­
  and  maritime  research  projects.
One  of  the  most  important  applications  of  the  numerical  models  is  the  support  of  the
BSH’s  water  level  prediction  and  storm  surge  warning  service,  which  is  supplied  with
computed  water  level  forecasts.  Other  important  applications  are  drift  prognoses  for  oil,
chemicals  and  dangerous  drifting  objects  as  well  as  the  support  of  search  and  rescue
operations.  Operational  model  data  have  been  used  successfully  in  marine  pollution
combating  operations  (Theobald  et  al.,  1992,  Dahlmann  and  Müller-Navarra,  1997,
Huber  and  Dick,  1998).  Occasionally,  drift  calculations  for  plankton  and  larvae  have  been
carried  out  to  support  fisheries.
The  BSH  receives  many  inquiries  concerning  current  data.  Its  model  data  have  been
used,  e.g.,  in  tidal  stream  atlases  (e.g.  Dick  et  al.,  1992),  for  ship  routing  and  in  the
preparation  of  sailing  competitions.  Meanwhile,  modelled  current  nowcasts  and  forecasts
(hours  to  days  ahead)  for  maritime  shipping  are  also  available  on  the  Internet
(www.bsh.de).  It  will  be  possible  in  future  to  integrate  these  and  other  model  predictions
into  electronic  chart  displays  (ECDIS).  Future  applications  will  include  model  predictions
to  support  the  BSH's  ice  and  sea  surface  temperature  service,  tidal  reduction  of  soundings ­
  in  hydrographic  surveying,  and  charting  on  the  basis  of  computed  water  level  data.
The  model  system  comprises  several  computer  programmes  which  automatically
produce  data  without  any  manual  intervention  being  required  (Fig.  1).  On  the  basis  of
meteorological  and  wave  forecasts  supplied  by  the  German  Weather  Service  (Deutscher
Wetterdienst,  DWD)  as  well  as  tide  predictions,  the  model  computes  a  daily  "weather
forecast”  for  the  sea.  The  model  system  is  an  in-house  development  of  BSH.  Its  main
constituents  are  a  hydrodynamical  model  to  compute  currents,  water  levels  and
temperatures,  salinities  and  ice  cover  in  the  North  and  Baltic  Seas  (BSH  circulation
model,  BSHcmod)  and  programmes  to  compute  the  drift  and  dispersion  of  substances
(Lagrangian  and  Eulerian  dispersion  models,  BSHdmod.L  and  BSHdmod.E).  Other
components  of  the  model  system  are  a  surge  model  (BSHsmod),  which  has  been
developed  to  support  the  water  level  prediction  service  with  medium  range  (84  hours)
surge  predictions  (Janssen,  1996,  Janssen  and  Dick,  in  prep.),  and  regional  models  for
selected  German  estuaries  and  coastal  areas  (e.g.  Dick  and  Schönfeld,  1996).

1  Federal  Maritime  and  Hydrographie  Agency,  formerly:  Deutsches  Hydrographisches  Institut  (DHI)