In today's discussion, the Dvorak digital IR technique is used to assign T-numbers for intensity estimations. The algorithm developed by Dvorak extracts two temperatures from the IR data and relates them to current intensity. A 55 km circle centered on the eye is used to find the surrounding temperature.
Intensity increases as the surrounding temperature decreases.
The warmest IR pixel in the eye is the other temperature, and intensity increases as eye temperature increases. Dvorak expresses intensity in terms of an index or T-no. corresponding to typical daily intensity changes. Tropical Cyclone Intensity Analysis Using Satellite Data. The red line is the T number, considering a 55 km. These values can be converted to Maximum Surface Wind Speed and Minimum Sea-Level Pressure.