Tropical Cyclone Surface Wind Field
A surface wind field is approximated by using the wind radii from the Forecast/Advisory product as input. These radii are defined as the maximum extent of sustained winds at each threshold (tropical storm and hurricane force) in each quadrant (northeast, southeast, southwest, and northwest).
For the production of a continuous wind field, the maximum extent of the wind field for each quadrant is assumed to occur at the center of the respective quadrant - that is, for the northeast quadrant the radii is assumed to be defined only due northeast of the storm center. With this assumption the radii are defined explicitly only at the four quadrant compass directions (due northeast, southeast, southwest, and northwest), the smooth wind field depicted on the graphic is produced by a trigonometric interpolation between the four defined radii.
The wind field depicted by this methodology should be treated as approximate, as over and under representations of the wind field may occur due to interpolation and smoothing.