Inner-core lightning outbreaks and convective evolution in Super Typhoon Haiyan (2013)

Using lightning data from the World Wide Lightning Location Network, infrared satellite imagery, and micro-wave observations, this study investigates lightning outbreaks and convective evolution in the inner core (0-100 km) of Super Typhoon Haiyan (2013), the strongest storm on record to make landfall in the northwest Pacific. This storm was characterized by intense lightning activity with half of the strokes occurring in the inner core. Three major inner-core lightning outbreaks and convective bursts (CBs) were observed during rapid intensification (RI), maximum intensity (MI), and weakening stages. These outbreaks coincided with favorable large-scale environmental conditions for TC development with higher sea surface temperature (29-30 degrees C), higher relative humidity (75-80%), and weaker deep-layer vertical wind shear (3-8 m s(-1)), compared to the climatological averages for the month of November in the northwest Pacific. The RI lightning outbreak occurred primarily in the downshear quadrants and CBs were located inside the radius of maximum wind (RMW). The MI lightning outbreak occurred just after the eyewall replacement cycle, inducing marked depression of brightness temperature at 91-GHz. The lightning outbreak during Haiyan's weakening stage preferred the upshear-left quadrant outside the RMW. In contrast, relative lack of cloud-to-ground lightning in the rainbands was observed during all three main outbreaks. The radial and azimuthal distributions of lightning outbreak within the inner core provided indicative information on the relationships between convective structure and intensity changes of Haiyan.