Variability of lightning flash and thunderstorm over East/Southeast Asia on the ENSO time scales

•Responses of lightning and thunderstorms to ENSO show seasonal and regional variations.•Lightning anomaly is positively correlated with the Oceanic Niño Index during El Niño episodes.•Lightning variation follows thunderstorm intensity (number) variation over East China during El Niño (La Niña).•Lightning variation follows a combination variation of thunderstorm intensity and number over Indonesia.

The variability of lightning flash and thunderstorm on the ENSO time scales over East/Southeast Asia was investigated by using 17-year (1995–2011) lightning data from the Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS), and 14-year (1998–2011) Tropical Rainfall Measuring Mission satellite (TRMM) precipitation feature data. In addition, ERA-Interim reanalysis data of the European Centre for Medium-Range Weather Forecasts (ECMWF) were used to present related environmental characteristics. It was found that the response of lightning flash to ENSO events shows remarkable seasonal and regional variations. The regions of positive (negative) lightning anomaly are mainly located at both sides of 5°–20°N (5°–15°N) in El Niño (La Niña) spring and winter, and located north of the equator in summer and autumn. There is a significantly positive correlation between lightning anomaly and the Oceanic Niño Index (ONI) over both East China and Indonesia during El Niño episodes, but no obvious correlation during La Niña episodes. The positive thunderstorm anomalies during El Niño periods are dispersed. The distribution of thunderstorm anomalies in La Niña summer and autumn is almost opposite to that in spring and winter. The correlation between thunderstorm anomaly and ONI is better over East China than that over Indonesia. In general, lightning variation follows thunderstorm intensity (number) variation over East China during El Niño (La Niña) episodes, and follows a combination of thunderstorm intensity and number variations over Indonesia on ENSO time scales. During ENSO time scales, variations of surface wind can be considered as one of the key factors to LAs. More lightning flashes present in the regions where warm moist flows intersection, and less in the regions where surface wind changes slightly or diverges. Dramatic lightning increases also occur with higher values of convective available potential energy (CAPE). In addition, higher (lower) 850 hPa relative humidity generally follows with more (less) lightning flashes, which is more obvious during El Niño episodes.