Quality controlled and homogenized radiosonde observations have been used to
validate decadal hindcasts of the MPI-Earth-System-Model for Europe (excl.
some Eastern European countries). Simulated temperatures have a cold bias of 1
to 4 K, increasing with height throughout the free troposphere over Europe.
This implies that the simulated troposphere is less stable than observed by
the radiosondes over Europe. Simulated relative humidity is 10 to 40 % higher
than observed. Part of the humidity bias, 10 to 25 % relative humidity, is due
to the simulated lower temperature, but the remainder indicates that modelled
water vapour pressure is too high in the free troposphere above Europe. After
full-field initialization with oceanic state, the atmospheric temperature bias
changes over the first couple of years, with a relaxation time of 5 years near
the surface (850 hPa) and less than 1 year near the tropopause (200 hPa).
Anomaly correlations, mean-square error and logarithmic ensemble spread score
indicate small improvements in hindcasted tropospheric temperatures over
Europe when going from ocean anomaly initialisation to ocean anomaly
initialisation plus full field atmospheric initialisation, and then to full
field ocean initialisation plus full field atmospheric initialisation. In the
stratosphere, these changes have little effect. For humidity, correlations and
skill scores are much poorer, and little can be said about changes over Europe
due to different initializations