ROLE OF DIFFERENTIAL FRICTION AND ASYMMETRY OF THE TOTAL FLOW ON HURRICANE MOVEMENT

GANDIKOTA V. RAO National Hurricane Research Laboratory, ESSA, Miami, Fla.

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Abstract

Under elementary considerations the vorticity changes induced by differential friction and asymmetry of the combined hurricane and large-scale flows were incorporated in the prediction equation and integrated with a view to forecasting the movement of hurricanes. After determining the difference between frictional and frictionless forecasts based upon idealized data, seven 24-hr and four 48-hr frictional and frictionless forecasts of the movement of hurricane Cleo, 1964, were obtained. Introduction of surface friction resulted in improved 24-hr directions of movement and reduced the magnitude of vector error in the 48-hr displacement. Causes underlying the observed improvement were analyzed.

*Presently a National Research Council Fellow at the Meteorological Service of Canada, Toronto

Abstract

Under elementary considerations the vorticity changes induced by differential friction and asymmetry of the combined hurricane and large-scale flows were incorporated in the prediction equation and integrated with a view to forecasting the movement of hurricanes. After determining the difference between frictional and frictionless forecasts based upon idealized data, seven 24-hr and four 48-hr frictional and frictionless forecasts of the movement of hurricane Cleo, 1964, were obtained. Introduction of surface friction resulted in improved 24-hr directions of movement and reduced the magnitude of vector error in the 48-hr displacement. Causes underlying the observed improvement were analyzed.

*Presently a National Research Council Fellow at the Meteorological Service of Canada, Toronto

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