Models, Data, and Methodology - On the Effect of Offshore Wind Farms on the Atmosphere and Ocean Dynamics - page 27

encircled area defines the model area of the finally used HAMSOM North Sea
(HAMSOM NS) simulation. The orange marked area shows the model area of
METRAS, including Germany s EEZ (light blue).

'

HAMSOM NES (Green)
HAMSOM NES comprises ocean simulations of the North Sea and the north
European shelf to provide initial data of surface elevation for ocean simulations
over the smaller ocean domain HAMSOM NS. HAMSOM NES has a horizontal
resolution of 20 20 km, and in the vertical the resolution counts 5 m from 0 to
50 m depths, 10 m from 50 to 100 m, 20 m between 100 and 200 m, and 50 m from
200 to 700 m. The topography of the ocean bottom is given in Fig. 3.6 . The
boundaries are treated as open in case of no coast. The temperature and salinity at
the model boundaries are climatological data from WOA-01. HAMSOM NES is
meteorologically forced with Era-Interim data every 6 h. The time step of simula-
tions is 1 minute. Simulations were done for the years 2010 and 2011.

HAMSOM NS (Red)
HAMSOM NS comprises ocean simulations of the North Sea with a horizontal
resolution of 3 km

3 km. The vertical resolution is equal to the one of HAMSOM
NES, and the topography is similar but logically spanned only over the model
domain of HAMSOM NS. The boundaries are treated as open in case of no coast.
The temperature and salinity at model boundaries are climatological data from
WOA-01, and the initial surface elevation is based on calculations by HAMSOM
NES. The time step of simulations over HAMSOM NS counts 1 min and provides a
10-min mean output.

Simulation time and meteorological forcing differs for simulations of case study
I (analysis of OWF effect related to wind directions) and case study II (OWF effect
under a realistic meteorological situation).
Setup for Case Study I: Constant Wind Directions
For case study I, 2

8 simulations were done on 1 June 2011: eight runs with
operating OWFs and eight runs without OWFs.

The forcing for HAMSOM NS is adopted every 10 min and comprises 10-m
wind fields, surface pressure, 10-m temperature, and 10-m humidity fields. The
meteorological forcing consists only of METRAS data. Due to the fact that the
model domain of METRAS in Fig. 3.6 (orange square) does not fit with the model
domain of HAMSOM NS, the METRAS forcing at orange boundary was expanded
over the whole HAMSOM NS domain.
Simulations of METRAS forcing data are based on a prescribed geostrophic
wind of 8 m/s, meteorological conditions of an early summer day with an initial
surface pressure of 1,000 hPa, 10-m temperatures of 17 C and 10-m humidity of
70 %. The diurnal cycle of the sun is determined by 1 June 2011. METRAS uses a
constant SST of 15 C and a light stable and neutral moist atmosphere.