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Droughts are widespread disasters worldwide and are concurrently influenced by multiple large-scale climate signals. This is particularly true over Japan, where drought has strong heterogeneity due to multiple factors such as monsoon, topography, and ocean circulations. Regional heterogeneity poses challenges for drought prediction and management. To overcome this difficulty, this study provides a comprehensive analysis of teleconnection between climate signals and homogeneous drought zones over Japan. First, droughts are characterized by simulated soil moisture from a land surface model during 1958–2012. The Mclust toolkit, distinct empirical orthogonal function, and wavelet coherence analysis are used, respectively, to investigate the homogeneous drought zone, principal component of each homogeneous zone, and teleconnection between climate signals and drought. Results indicate that nine homogeneous drought zones with different characteristics are defined and quantified. Among these nine zones, zone 1 is dominated by extreme drought events. Zones 2 and 6 are typical representatives of spring droughts, whereas zone 7 is wet for most of the period. The Hokkaido region is divided into wetter zone 4 and drier zone 9. Zones 3, 5, and 8 are distinguished by the topography. The analyses also reveal almost all nine zones have a high level of homogeneity, with more than 60% explained variance. Also, these nine zones are dominated by different large-scale climate signals: the Arctic Oscillation has the strongest impact on zones 1, 7, and 8; the influence of the North Atlantic Oscillation on zones 3, 4, and 6 is significant; zones 2 and 9 are both dominated by the Pacific decadal oscillation; and El Niño–Southern Oscillation dominates zone 5. The results will be valuable for drought management and drought prevention. [ABSTRACT FROM AUTHOR]

The spatial-temporal characteristics of wildfires were summarized based on fire reports covering 55,863 wildfires with a total burned area of 289.91 km2 from 1995 to 2020 in Japan. The long-term decreasing trend was largely influenced by changes in social aspects, while the annual fluctuation was determined by large-scale events. The wildfire season started around early January in the southern part and gradually shifted northward over approximately three months. A total of 98.77% of cases were human-induced, and 1.23% were caused by lightning. Regarding response time after receiving the call, firefighting was started within 30 min in 89% of cases and controlled within 1 h in 85% of cases, where spatial characteristics were insignificant. Full-time fire departments utilized artificial water sources primarily in 72% of cases and natural water sources in 28%, while the rate using natural water sources increased as the burned area increased. Natural water sources from ponds and rivers exhibited regionalities. Cluster analysis revealed five wildfire regions reflecting natural and anthropogenic factors. Furthermore, the Mann–Kendall trend test concluded that the initiation process decreased almost uniformly across the country, while regional differences existed regarding the expansion process. Additionally, only human-induced wildfires had a significant decreasing trend. • The fire reports of 55,863 wildfire cases from 1995 to 2020 were summarized. • The decreasing trend of the number of fires was significant and human-influenced. • A total of 98.77% of wildfires were human-induced, and 1.23% were by lightning. • Firefighting was started in 30 min in 89% of cases after receiving the call. • 72% of cases used artificial water sources, and large cases needed natural sources. [ABSTRACT FROM AUTHOR]