43

7  Model  simulations  as  part  of  the  project
The  BSH  model  system  comprises  three  models.  A  two-dimensional,  barotropic  model  of  the
North-East  Atlantic  Ocean  computes  the  boundary  conditions  for  a  three-dimensional
baroclinic  model  of  the  North  and  Baltic  Seas,  especially  to  account  for  the  occurrence  of
external  surges.  A  higher-resolution  model  of  the  German  Bight  and  western  Baltic  Sea  is
interactively  nested  into  the  latter  model  (Dick  et  al.  2001).  Additionally,  a  two-dimensional
barotropic  model  of  the  North  Sea  (North  Sea  10  km)  is  available  for  fast  forecasts  of  storm
surges  (Müller-Navarra  et  al.  2003).  These  models  solve  hydrostatic  non-linear  shallow  water
equations  taking  into  account  variable  bottom  topography  and  bottom  friction.

O'

s  E

id'E

bo'N

M  N

E3'N

so  N

w  N

o'  a'E  io  E

Hirtsholm

Aberdeen

North  Shields

&
Cuxhavei

Borkum

■Immingham

Ijmuiden
■we  stoft.

a  SO  1  CO  13D  2  CO  230  2CO  350  400

Fig.  7.0.1:  Bathymetry  of  the  BSH's  "North  Sea  2  km"  model.

As  has  been  pointed  out  under  5  above,  the  model  equations  of  the  North  and  Baltic  Sea
model  are  suitable,  in  principle,  for  modelling  the  propagation  and  modification  of  tsunami  on
the  shelf.  In  contrast,  the  North-East  Atlantic  model  has  only  limited  suitability  for  computing
tsunami  propagation  in  the  deep  ocean  and  its  modification  on  the  continental  slope.
Adequate  simulation  of  tsunami  in  the  North  Sea,  therefore,  first  of  all  requires  a  profound