Environments conducive to cloud-to-ground and ignited lightning in a boreal forest of Northeast China

Abstract

Cloud-to-ground (CG) lightning is the main ignition source for wildfires in boreal forests. Characterizing the environmental controls on both CG lightning occurrence and ignition success is therefore essential for developing effective early warning systems. However, previous analyses of conditions favorable for lightning often involved the incorporation of non-igniting intracloud (IC) lightning because of data limitations, creating a significant knowledge gap. This gap is particularly acute in the Greater Khingan Mountains (GKM) of China, which contain largest boreal forest and experience the highest frequency of lightning-ignited wildfires (LIWs). In this study, meteorological, atmospheric, aerosol, and land-surface datasets from 2019 to 2023, along with lightning records and LIW occurrences, are synthesized to distinguish igniting lightning and identify the key determinants of CG lightning occurrences and ignition success. The results indicated that CG lightning occurs preferentially in higher-elevation mountainous areas that are dominated by needle-leaved deciduous forests. Statistical analyses revealed significant (p < 0.01) associations between CG lightning occurrences and elevated aerosol loadings, higher temperatures, greater precipitation levels, and enhanced vertical atmospheric instability. Furthermore, compared with non-igniting CG lightning, igniting lightning is associated with greater atmospheric instability and stronger updrafts, along with significantly warmer and drier land-surface conditions that promote fuel aridity. Collectively, these findings establish a conceptual framework for identifying high-risk lightning events and achieving enhanced early targeted LIW warning capabilities.