An Investigation of Systematic Errors in the Barotropic Forecasts

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Martin, Lt. Col. Donald E. (2011)

Forecast-errors in the 24- and 48-hour barotropic 500-mb prognostic charts prepared by JNWPU for the winter of 1957 were investigated. Certain large-scale forecast-errors were found to persist from day-to-day in fairly localized geographical areas. In general, the numerical prognoses exhibited a tendency to forecast excessively high values off the southeastern coasts and excessively low values off the northwestern coasts of the continents. Little forecast-error was observed in the continental interiors. A Fourier analysis revealed that the forecast-errors were largely due to incorrect phase forecasts for wave numbers 1 through 4. The forecast-errors associated with wave number 1 usually “positioned” the large-scale systematic forecast-errors near Japan and Scandinavia and contributed materially to their intensities. Relationships between forecast-error fields and topography, geography, synoptic situation, and “non-adiabatic” heating are discussed. Hemispheric fields of “non-adiabatic” heating, computed using a two-level graphical model, are shown. Charts illustrating the dependence of “non-adiabatic” heating on the general circulation are also shown.DOI: 10.1111/j.2153-3490.1958.tb02033.x
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