Tornado environments derived from ERA5 over Indonesia

Abstract Tropical maritime regions, such as Indonesia, experience tornadoes. However, the tornado environment in Indonesia remains poorly understood. In this study, we analyzed convective and kinematic parameters associated with 119 tornado cases from 2010 to 2024. Prior to examining tornado environments, the performance of ERA5 reanalysis was evaluated against sounding observations. ERA5 tends to underestimate some parameters in tropical maritime regions, particularly low-level parameters (0–1 km) compared to mid- and deep-level parameters (0–3 km and 0–6 km). Both convective available potential energy (CAPE) and the lapse rate at 0–1 km increase prior to tornadogenesis, highlighting their importance for storm development. CAPE in Indonesia is comparable to that in the U.S. Great Plains, while LR01km is higher than in mid-latitude environments. Shear and storm-relative helicity (SRH) are lower than those observed in mid-latitude regions. Overall, thermodynamic conditions are more conducive to tornado formation in Indonesia than kinematic conditions.