24

contributions  of  DWD  to  a  wide  range  of  users.
German  GOOS  Secretariat
The  German  GOOS  Secretariat  hosted  by  the  DWD  since  October  1992  supports  the  German
representatives  in  the  GCOS  bodies,  helps  to  co-ordinate  the  German  contribution  to  the
climate  module  of  GOOS  and  provides  information.  The  focus  of  its  work  is  on  the  Joint  Data
and  Information  Management  Panel  (J-DIMP).

DWD-P3  Operational  marine  meteorological  applications  and  services
Objectives
to  supply  customers  with  marine  meteorological  forecasts,  warnings,  advice,  expert
opinions,  and  real-time  observation  data
to  compile  marine  climatological  basic  data,  partly  on  behalf  of  WMO,  for  use  by  marine
meteorological  and  oceanographic  services,  scientific  and  nautical  institutions  and  the
public.
Present  scientific  knowledge  and  methods  used
The  operational  marine  meteorological  services  make  forecasts  and  issue  warnings  which  are
mainly  based  on  the  results  of  model  computations.  Empirical  methods  prevail  only  in
nowcasting  (0-2  hours)  and  short-term  forecasts  (up  to  about  12  hours).  Owing  to  the
availability  of  latest  state-of-the-art  mainframe  computers,  the  capabilities  of  numerical
weather  predictions  are  continually  improved.
For  example,  the  Global  Model  of  the  German  Weather  Service  computes  forecasts  with  a
horizontal  resolution  of  1.1°  and  19  vertical  layers.  The  prediction  period  covers  7  days.  The
model  performance  will  be  further  improved  shortly  by  refining  the  gridsize  to  50  km.  Periods
up  to  about  10  days  can  be  covered  by  deterministic  predictions.  This  period  can  be  extended
even  further  by  using  the  ensemble  technique.
Nested  models  provide  much  higher  resolutions  for  shorter  prediction  periods.  The  Germany
model  of  DWD  uses  resolutions  of  14  km  and  30  layers,  with  a  prediction  period  of  48  hours.
A  reduction  of  the  grid  resolution  to  8  km  will  be  carried  out  shortly,  and  a  further  reduction
is  being  planned.  In  the  new  model,  within  the  framework  of  non-hydrostatic  equations,
vertical  motions  will  be  ascertained  directly.  The  deterministic  output  is  improved  by  filtering
techniques  such  as  Kalman  filtering  and  statistical  methods  like  the  perfect-prog  method  or
model  output  statistics  (MOS).
A  crucial  requirement  in  numerical  weather  forecasting  is  the  consideration  of  oceanatmosphere
  coupling.  The  manifold  momentum,  energy,  and  mass  transfer  processes  at  the  sea
surface  play  an  important  role,  especially  in  medium-  and  long-term  predictions.  Recently
models  have  been  introduced  taking  into  account  these  processes.
For  wave  predictions,  models  are  used  which  are  forced  by  the  predicted  windfields  from
numerical  weather  prediction  models.  The  DWD,  e.g.,  uses  a  hybrid  2 nd  generation  wave
model.  Computations  are  made  for  the  North  Atlantic  (130  km  /  7  days),  the  European  Shelf
(30  km  /  78  hours),  and  the  Baltic  Sea  (15  km  /  78  hours).  The  follow-up  model,  the  3 rd
generation  wave  model,  will  be  applied  on  a  global  scale  and  will  also  cover  the  Mediterranean
and  North  and  Baltic  Seas,  and  it  will  be  coupled  to  atmospheric  models  and  additionally,  in