Estimation of the Relation between the Electrical Properties of Lightning and Tropical Cyclone Intensity in Western North Pacific

Abstract:

Prediction of the Tropical Cyclone (TC) intensity such as maximum sustained wind and minimum sea surface pressure is an important issue for a long time. Previous studies suggested that lightning activity in TCs has a possibility to improve the accuracy of intensity prediction. Although relationships between lightning frequency and TC intensity have been investigated in the previous studies, relationships of electrical properties(EPs) of lightning with TC intensity have not been studied. In this study, we investigated the relationships of EPs of lightning (peak current, charge moment change (CMC) and charge amount) with five TCs (LEEPI, category1; UTOR, category5; MAN-YI, category3, Large; WIPHA, category4, Large; HAIYAN, category5) over the Western North Pacific. We used the best track data of TCs provided by Joint Typhoon Warning Center (JTWC), time and location of lightning data provided by World Wide Lightning Network (WWLLN) and ELF magnetic field data obtained at two stations of Global ELF Observation Network (GEON), Syowa (69.0S, 39.5E) and Kuju(33.1N, 131.2E) for calculating EPs. In order to compare TC intensity with lightning parameters, EPs of lightning in the inner core region (100 km from the center of TC, 200 km for large TCs) and in the rainband region ( 100 km ~ 500 km from the center, 200 km ~ 1000 km for large TCs), median values of the cross-correlation coefficients and lag time were calculated. In the case of UTOR and HAIYAN that were intense TCs, the correlation coefficients of peak current and charge amount of lightning in the inner core with TC intensity were relatively high. In addition, each peak of lightning parameters preceded that of TC intensity by ~ 1day. However, there was very weak correlation in TC intensity and EPs of lightning in the rainband of TCs with category 4,5 including WIPHA. The rainband region of relatively weak TCs (LEEPI and MAN-YI) had the peak of EPs of lightning 1~2 days before the peak of maximum sustained wind. From these results, EPs of lightning in the inner core of intense TCs can be a possible indicator of TC development.