Understanding the Cyan Ring Signature in 37-GHz Passive Microwave Imagery through Airborne Radar

A cyan ring signature is a pattern that appears around the eye of an intensifying tropical cyclone when viewed in 37-GHz passive microwave color composite imagery and is often associated with rapid intensification. While this pattern is well documented and is used in an operational setting to predict rapid intensification, comparatively little work has been done to understand what this feature physically represents from an observational standpoint. To this end, the present study uses high-altitude airborne radar and passive microwave data collected during a number of field campaigns in combination with satellite infrared and passive microwave imagery to investigate the physical structures that produce these cyan rings and their relationship to rapid intensification. Specifically, the field campaigns from which this study will draw data include CAMEX-3 (1998), CAMEX-4 (2001), and TCSP (2005) and will use data collected by the EDOP X-band Doppler radar and the AMPR passive microwave radiometer, both flown aboard the NASA ER-2.