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A spectral barotropic model in horizontal empirical orthogonal functions
Author(s) -
Rinne Juhani,
Karhila Vesa
Publication year - 1975
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49710142817
Subject(s) - barotropic fluid , empirical orthogonal functions , smoothing , enstrophy , inflow , mathematics , harmonics , boundary value problem , mathematical analysis , representation (politics) , vorticity , meteorology , geology , physics , climatology , statistics , vortex , voltage , quantum mechanics , politics , political science , law
A limited area barotropic vorticity equation model is integrated using a representation in terms of 57 horizontal empirical orthogonal functions. No boundary conditions are applied; the inflow and outflow of weather systems are absolutely free. The length of the time step in a normal centred scheme can be as much as 10 hours. With a time step of 6 hours, the model was integrated up to ten days without any smoothing, and the energy and enstrophy terms still had reasonable values. The skill of the forecasts is at least as good as, probably better than, comparison finite difference forecasts. The present climatological functions were transformed to make them closer to two‐dimensional harmonics. About half of the new functions resembled two dimensional harmonics; their wave lengths were about 3000–5000km.