NOGAPS (Numerical Operational Global Atmospheric Prediction System) Verification Using Spectral Components.
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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In this study, one three-day and two five-day Numerical Operational Global Atmospheric Prediction System NOGAPS, 500mb forecasts were spectrally verified. The wavenumber components of the observed and forecasts waves were grouped into planetary wavenumbers 1-3, long wavenumbers 5-7 and medium wavenumbers 8-12 wavenumbers for verification. The observed and forecast trough-ridge hovmoller diagrams of longitude versus time for each group were analyzed for each case. In all three cases, the most serious errors occurred in the planetary waves where the model often forecast erroneously large or small amplitudes. The long waves were the most accurately forecast group both in amplitude and phase speed. The medium wave amplitudes were forecast too weak and phase speeds were consistantly too fast for this group. Author