Inter-annual Variation of Wildfire Area in China and Its Meteorological Conditions Based on Random Forest

Yang Xiting; Chyi Dorina; Yang Yanrong; Zhang Leying

doi:10.16765/j.cnki.1673-7148.2025.06.003

Abstract：Wildfire exerts great influences on the ecosystem and climate change.Analyzing its inter-annual variability and mechanisms could deepen the understanding of wildfire variability and provide sci-entific basis for fire prevention decision-making in China.Using the burned area data from GFED4 and MODIS satellite remote sensing and ERA5 re-analysis data,this study explores the inter-annual variability of wildfire burned area by means of power spectrum analysis.Then,the key meteorological factors,which dominate the inter-annual variation of wildfire area,and their circulation characteristics are identified by the random forest model and correlation/regression analysis.The results show that:(1)South China(January to March),Southwest China(February to April)and Northeast China(March to May)are the key wildfire regions with significant inter-annual variations in wildfire burned area in China and the inter-annual cycle of each significant area is different.There is an inter-annual cycle of 4 to 6 years for the wildfire burned area in South China and a 3-year cycle in Northeast China.(2)Relative humidity is a key meteorological factor for the inter-annual variation of wildfires in South China and Northeast China,and it shows a significant negative correlation with the area of wildfires.Wind speed is a key meteorological fac-tor in Southwest China and has a significant positive correlation with the area of wildfires.(3)Distinct at-mospheric circulations exist in different key regions.The westerly(southwesterly)wind on the south side of the abnormal low sea level pressure in Southwest China is positively abnormal,which increases the cli-matological wind speed and is conducive to the spread of fire.Local high-pressure anomaly appears in Northeast China with descending motion,and the sinking airflow reduces the near-surface relative humidity,benefiting the increase in wildfire burned area.However,no significant circulation anomaly is found in South China.