Bonekamp H ,
Sterl A ,
Komen GJ ,
Burgers G ,
Oldenborgh GJ van ,
Janssen PAEM
140 p
in Dutch
2001
Toon Nederlands
English Abstract As a contribution to ongoing efforts in modelling of
the coupled atmosphere/ocean system we have assessed global fields of
air/sea fluxes of heat and momentum, produced as part of the European Centre
for Medium-range Weather Forecast Reanalysis project (ERA). In the wave
part of this project we made a 15-year simulation of the global wave
climate, by forcing a reliable wave model with ERA winds, and by compiling a
data base of wave observations. By comparing the wave model response with
the observed wave heights we were able to assess the quality of the ERA
surface winds, and associated momentum fluxes. In general, agreement was
good, confirming the accuracy of ERA. However, high waves were
underpredicted. We have given arguments that this underprediction results
from the relatively low resolution of the atmospheric model. We have also
studied the wind stress parameterization of the planned 40-year reanalysis
(ERA40). In this reanalysis the aerodynamical roughness of the sea surface
depends on the sea state which is calculated with the wave model. We have
found that the ERA40 parameterization leads to a better representation of
observed wind stress variability. In the ocean part of the project we
assessed heat and momentum fluxes by forcing general circulation models of
the ocean and by comparing the (upper) ocean temperature response with
observations of the deeper ocean. Although the scope of our study is global
we made a special study of the response of the Southern Ocean and of the
Tropical Pacific. From our Southern Ocean study the main conclusion was
that ERA has a realistic interannual variability in heat and momentum
fluxes. In our Tropical Pacific study we developed a method which allows
the improvement of both the fluxes and the ocean
analysis.