Proceedings - C-SRNWP Project

Fig. 1: Examples of verification scores showing the improved performance of 4D-VAR with
respect to 3D-VAR. Fig. 1a shows an upper air score verification for wind and temperature
for the month January 2006. Red lines indicate version 7.0 with 4D-VAR, the blue ones
version 7.0 with 3D-VAR. Fig. 1b shows rms and bias for mean sea level pressure, verified
against EWGLAM stations. In this case, blue lines indicate 4D-VAR, and red ones 3D-VAR.
In both cases a clear beneficial impact of 4D-VAR is observed. This has also been shown to
be the case for months in other seasons.
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