![]() Halos, as relatively non-structured phenomena of diffusive emission that often accompany sprites (in the form of halo sprites), usually appear at relatively high altitudes ( Frey et al., 2007). In particular, the documented fraction of sprites produced by negative CG strokes is substantially smaller than that inferred from the ground-based measurement of lightning strength on a global scale (e.g., Füllekrug et al., 2002 Sato and Fukunishi, 2003), constituting a sprite polarity paradox ( Williams et al., 2007). However, the ground-based observations over continental thunderstorms show that, despite of the well-known dominance of negative CG lightning on the land, the vast majority of sprites observed over continental thunderstorms are produced by positive CG strokes (e.g., Li et al., 2012). When the electric field ( E-field) change caused by the charge transfer from thundercloud to ground exceeds the critical value of conventional breakdown ( E k) at certain altitude, the ionization will be initiated and became sustained only if the ambient E-field remains higher than E k ( Pasko et al., 1997 Qin et al., 2013). ![]() Lightning strokes of either polarity (i.e., positive or negative) could produce sprites. Coordinated observations combining with the measurement of radio-frequency (RF) electromagnetic fields radiated by sprite-producing lightning strokes have revealed many details regarding the mechanism of sprite formation in the mesosphere (e.g., Li et al., 2012 Cummer et al., 2013 2016 Ren et al., 2019 Kuo et al., 2021). In the past 3 decades, the efforts of many researchers all over the world, including numerous amateurs, have confirmed that red sprites are a fairly common phenomenon that could be produced by energetic cloud-to-ground (CG) lightning strokes spawned by various types of thunderstorms ( Lyons, 1996 Huang et al., 2018a, Huang et al. ![]() Red sprites are one primary category of transient luminous events (TLEs) appearing at altitudes of 50–90 km in the near space that are believed to be caused by intense tropospheric lightning ( Pasko et al., 1997 Huang et al., 1999). It seems that the production of negative sprites heavily depends on the size of parent thunderstorms, and they are often generated by thunderstorm conditions that are also favorable for gigantic jets. There have been analyses on several cases of oceanic thunderstorms abundant in producing negative sprites. ![]() However, the physical mechanisms that might cause the enhancement of negative CG strength in the ocean remain not completely understood. The existing ground-based observations in both Caribbean Sea and near the coast of South China, mainly due to the contributions from numerous amateurs, are generally consistent with the implications of ISUAL observations. By combining with ground-based measurements of causative strokes for hundreds of red sprites observed by the Imager of Sprites and Upper Atmospheric Lightnings (ISUAL) during 2004–2016, there is a consensus that negative cloud-to-ground (CG) strokes spawned by oceanic thunderstorms are more readily to produce sprites. The observations of transient luminous events from space-borne platform extend our exploration on the mysteries of sprite phenomenology from continental thunderstorms to oceanic thunderstorms. 8State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, China.7Guangzhou Power Supply Bureau, Guangzhou Power Grid Co, Ltd, China Southern Power Grid, Guangzhou, Guangdong, China.6Caribbean TLE Observatory, Cabo Rojo, PR, United States.5Beijing Meteorological Observation Center, Beijing, China.4Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.3Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, Jiangsu, China.2Key Laboratory of Atmospheric Optics, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, Anhui, China.1School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China.Gaopeng Lu 1,2,3* Kang-Ming Peng 1 Tao Xian 4 Yongping Wang 1 Huan Ren 1 Ye Tian 5 Mao Zhang 1 Frankie Lucena 6 Xiaoyang Zhang 7 Xin Huang 1 Zhengwei Cheng 8
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