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- Author or Editor: E. C. Jarvis x
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Abstract
The utility of Burke's graphs for predicting the modification of surface temperatures when a cold air mass passes over a warmer water surface is briefly reviewed. A method of re-labelling the abscissae, ordinates, and curves of Burke's original graphs is discussed. Their operational use is facilitated by adopting the conventional units in which the synoptic information is relayed, and by significantly reducing the number of necessary computations. The modified graphs are approximations of the originals, but give operationally useful predictions and provide a four-fold reduction in the time required to perform the computations.
Abstract
The utility of Burke's graphs for predicting the modification of surface temperatures when a cold air mass passes over a warmer water surface is briefly reviewed. A method of re-labelling the abscissae, ordinates, and curves of Burke's original graphs is discussed. Their operational use is facilitated by adopting the conventional units in which the synoptic information is relayed, and by significantly reducing the number of necessary computations. The modified graphs are approximations of the originals, but give operationally useful predictions and provide a four-fold reduction in the time required to perform the computations.
Abstract
A prediction equation used in graphical prognosis is adapted to a grid for predicting the displacement of cyclones near the east coast of North America. The primary displacement, found using the mean 500-mb geostrophic wind over the grid area, is adjusted for secondary displacements resulting from the variation in height of terrain, the rate of exchange of sensible heat at the sea-air interface, and the variation of Coriollis force with latitude. Estimates of central pressure can be made by relating the primary and secondary displacements to initial and forecast 500-mb height fields.
24-hr forecasts were made by the grid method of fifty method for fifty randomly selected cases and results were compared with 24-hr forecasts made using the Ostby-Veigas point-value regression equations. The grid method incurred a rms displacement error of 2.5 degrees latitude and a rms error in the change of central pressure of 8.1 mb. The Ostby-Veigas method had a rms displacement error of 3.3 degrees latitude and a rms error in change of central pressure of 11.1 mb.
Abstract
A prediction equation used in graphical prognosis is adapted to a grid for predicting the displacement of cyclones near the east coast of North America. The primary displacement, found using the mean 500-mb geostrophic wind over the grid area, is adjusted for secondary displacements resulting from the variation in height of terrain, the rate of exchange of sensible heat at the sea-air interface, and the variation of Coriollis force with latitude. Estimates of central pressure can be made by relating the primary and secondary displacements to initial and forecast 500-mb height fields.
24-hr forecasts were made by the grid method of fifty method for fifty randomly selected cases and results were compared with 24-hr forecasts made using the Ostby-Veigas point-value regression equations. The grid method incurred a rms displacement error of 2.5 degrees latitude and a rms error in the change of central pressure of 8.1 mb. The Ostby-Veigas method had a rms displacement error of 3.3 degrees latitude and a rms error in change of central pressure of 11.1 mb.
