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Ann. Geophys., 26, 1935-1954, 2008
www.ann-geophys.net/26/1935/2008/
© European Geosciences Union 2008
Verification of a coupled atmosphere-ocean model using satellite observations over the Adriatic Sea
V. Djurdjevic and B. Rajkovic
Institute of Meteorology, Faculty of Physics, Belgrade University, Belgrade, Serbia
Abstract. Verification of the EBU-POM regional atmosphere-ocean coupled model (RAOCM)
was carried out using satellite observations of SST and surface winds over
the Adriatic Sea. The atmospheric component has a horizontal resolution of
0.125 degree (approximately 10 km) and 32 vertical levels, while the ocean
component has a horizontal resolution of approximately 4 km with 21 sigma
vertical levels.
Verification of the forecasted SST was performed for 15 forecasts during
2006, each of them seven days long. These forecasts coincide with the
operating cycle of the Adriatic Regional Model (AREG), which provided the
initial fields and boundary conditions for the ocean component of EBU-POM.
Two sources of data were used for the initial and boundary conditions of the
atmosphere: primary data were obtained from the European Center for
Medium-Range Weather Forecasting (ECMWF), while data from National Centers
for Environmental Prediction (NCEP) were used to test the sensitivity to
boundary conditions.
Forecast skill was expressed in terms of BIAS and root mean square error
(RMSE). During most the of verification period, the model had a negative
BIAS of approximately −0.3°, while RMSE varied between 1.1° and
1.2°. Interestingly, these errors did not increase over time, which
means that the forecast skill did not decline during the integrations.
The 10-m wind verification was conducted for one period of 17 days in
February 2007, during a strong bora episode, for which satellite estimates
of surface winds were available. During the same period, SST measurements
were conducted twice a day, which enabled us to verify diurnal variations of
SST simulated by the RAOCM model. Since ECMWF's deterministic forecasts do
not cover such a long period, we decided to use the ECMWF analysis, i.e. we
ran the model in hindcast mode. The winds simulated in this analysis were
weaker than the satellite estimates, with a mean BIAS of −0.8 m/s.
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