RESEARCH IN OBJECTIVE WEATHER FORECASTING.
Summary rept. no. 2, 1 Jul 61-31 Dec 63,
DEUTSCHER WETTERDIENST FRANKFURT AM MAIN (WEST GERMANY)
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The numerical stability properties of a unfiltered baroclinic model which uses a simplified version and a periodic channel current are studied in detail. A numerical experiment on the behavior of initially barotropic disturbances in a baroclinic channel over a forecast period of 12 days is presented. For the experiments in most cases non-divergent initial wind fields were computed from the geopotential by means of the balance-equation the procedure applied for solving it is reported. A calculus which facilitates the derivation of the ellipticity criterion for more complicated forms of the balanceequation is introduced. Automatic decoding and objective analysis processes to be applied in order to obtain actual initial data in a format acceptable to computers are presented. A filtered method, which does not exclude the noise waves but rather converts these waves into harmless phenomena is considered. By use of a very simple linearized version of the barotropic model, the filtering process is studied more generally and hints for the specialisation of more efficient diagnostic relations in the atmosphere are included.