Study On The Responses Of Lightning Flashes And Thunderstorms To ENSO Evens Based Qn Satellite Observation

The ENSO events not only result in the change of atmospheric circulation, but also cause the distribution of lightning activity by affecting atmospheric circulation, local convection and meteorological factors. The variabilities of lightning flashes and thunderstorms over the tropical and subtropical region (35°S-35°N) and East/Southeast Asia (15°S-35°N,90°-130°E) on ENSO time scales were investigated in this paper, based on the lightning data (1995-2011) from the Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS), precipitation feature data (1998-2011) from the Tropical Rainfall Measuring Mission satellite (TRMM). In addition, the reanalysis data (1995-2011) from the European Centre for Medium-Range Weather Forecasts (ECMWF), the National Center for Atmospheric Research (NCEP) and the National Center for Atmospheric Research (NCAR) were used to present related variation of environmental characteristics. The main conclusions are as follows:1. There are four kinds of obvious different regions of the response of lightning activity to ENSO over tropic and subtropics during spring and winter. Firstly, lightning activity always increases on ENSO time scales, when the amplitude can exceed 20%. Secondly, lightning activity always decreases on ENSO time scales, when the amplitude can hardly exceed 50%. Thirdly, lightning activity increases during El Nino episodes and decreases during La Nina episodes. Lastly, lightning activity decreases during El Nino episodes and increases during La Nifia episodes. A significant positive correlation of lightning flashes and Oceanic Nino Index (ONI) exists in the equator and the oceans in the Southern Hemispheric and their coastal regions during El Nino episodes, while a significant negative correlation exists in the lands in the Southern Hemisphere lands during La Nina episodes.2. The correspondence of lightning anomaly and surface pressure anomaly always exists over the tropics and subtropics during ENSO spring and winter, and the areas warming during El Nino episodes (the areas cooling during La Nina episodes) have a better positive lightning-ONI correlation. Under the influence of El Nino, lightning variation and precipitation variation are synchronous over the Pacific and its surrounding regions, and are synchronous over the regions near the north Indian Ocean during La Nina episodes.3. The lightning positive (negative) anomaly regions are mainly located at the East China and the southern Indonesia during spring and winter of El Nino (La Nina), and located at north of the equator in summer and autumn. There is a significantly positive correlation of lightning anomaly and the Oceanic Nino Index (ONI) in both East China and Indonesia during El Nino episodes, but nearly no correlation during La Nifia episodes. The lightning variation rate in Indonesia (18%) is bigger than that in East China (10%) during El Nino episodes, and the lightning variation rate in East China (-21%) is very different from that in Indonesia (5%)during La Nina episodes.4. Spring is the season when has the most obvious thunderstorm anomaly during El Nino. Obvious thunderstorm negative anomaly can be found during La Nina spring and winter, while obvious positive anomaly during summer and autumn. Compared with lightning, thunderstorm anomaly has a weaker correlation with ONI, and the positive correlation in East China is stronger than that in Indonesia. The thunderstorm variation rates in East China (-12% during El Nifio and-35%during La Nina) are always bigger than that in Indonesia (7%during El Nino and-3% during La Nina). The effect of ENSO to lightning frequency of thunderstorm mainly appears in the deep convection whose maximum 40 dBZ height reaches over 10 km.5. Lightning anomaly follows both number and intensity variation of thunderstorm over Indonesia (East China) during El Nino (La Nifia), follows the intensity variation of thunderstorm over East China during El Nifio and the number variation of thunderstorm over Indonesia during La Nina.6. Compared with convective available potential energy (CAPE) and 850 hPa relative humidity, the variation of surface wind can be considered as a key factor to lightning anomaly over East/Southeast Asia during ENSO time scales. The increase of lightning generally occurs in the areas where warm moist flows intersection, and the decrease of lightning in the areas where surface wind changes slightly or even diverges, especially over the islands and coastal regions south of China. A large increase of lightning corresponds with increase of CAPE. In contrast with La Nina episodes, the better correspondences between CAPE anomaly,850 hPa relative humidity anomaly and lightning anomaly, affect the spatial distribution of lightning anomaly during El Nino episodes.