Pinhole eyes in tropical cyclones

This project examines the occurrence of pinhole eyes in tropical cyclones. In recent years several systems that underwent rapid intensification developed a very small eye in the process, often referred to as a ‘pinhole' eye. Understanding the processes and environmental factors involved in the development and maintenance of pinhole eyes could assist in prediction of tropical cyclone structure and intensification.

This project's approach is two-fold, starting with an observational climatology of pinhole eyes and progressing to numerical modeling of eye size. The climatology examines pinhole eyes occurring in tropical cyclones in the Atlantic Basin over the period 1989-2006. For this study pinhole eyes are defined as those eyes with a diameter smaller than 10 n mi, representing less than ten percent of the eye size measurements available in aircraft reconnaissance fixes. A combination of aircraft reconnaissance fixes, operationally-estimated size parameters, and synoptic data is used to examine the size and intensification properties of pinhole cases, as well as their large-scale environment. The results of this climatology are used to initialize sensitivity tests of eye size modulation in the Weather Research and Forecasting model.