Lightning Activity and Its Relation to the Intensity of Typhoons over the Northwest Pacific Ocean

ABSTRACT Data from the World Wide Lightning Location Network （WWLLN） were used to analyze the lightning activity and the relationship between maximum sustained wind and lightning rate in 69 tropical cyclones over the Northwest Pacific Ocean from 2005 to 2009. The minimum lightning density was observed in the category 2 typhoon Kong-Rey （2007）, with a value of only 1.15 d-1 （100 kin）-2. The maximum lightning density occurred in the category 2 typhoon Mitag （2007）, with a value of 510.42 d-1 （100 km）-2. The average lightning density decreased with radius from the typhoon center in both weak （categories 1-3） and super （categories 4-5） typhoons. The average lightning density in the inner core of super typhoons was more than twice as large as that for weak typhoons. Both groups of typhoons showed a near-monotonic decrease in lightning density with radius. Results also showed that lightning activity was more active in typhoons that made landfall than in those that did not. The mean correlation coefficient between the accumulated flashes within a 600-kin radius and the maximum wind speed in the weak typhoons and super typhoons was 0.81 and 0.74, respectively. For more than 78% （56%） of the super （weak） typhoons, the lightning activity peaked before the maximum sustained wind speed, with the most common leading time being 30 （60） h. The results suggest that, for the Northwest Pacific Ocean, lightning activity might be used as a measurement of the intensification of typhoons.

The lightning activities in super typhoons over the Northwest Pacific

The spatial and temporal characteristics of lightning activities have been studied in seven super typhoons from 2005 to 2008 over the Northwest Pacific, using data from the World Wide Lightning Location Network (WWLLN). The results indicated that there were three distinct lightning flash regions in mature typhoon, a significant maximum in the eyewall regions (20-80 km from the center), a minimum from 80-200 km, and a strong maximum in the outer rainbands (out of 200 km from the center). The lightning flashes in the outer rainbands were much more than those in the inner rainbands, and less than 1% of flashes occurred within 100 km of the center. Each typhoon produced eyewall lightning outbreak during the periods of its intensification, usually several hours prior to its maximum intensity, indicating that lightning activity might be used as a proxy of intensification of super typhoon. Little lightning occurred near the center after landing of the typhoon.