Spatiotemporal Distribution of Siberian Wildfires and Impacts from Meteorological and Climatic Factors

Wildfire is a major disturbance affecting carbon cycling, land–atmosphere energy exchange, and ecological security in high-latitude ecosystems. Siberia is one of the most fire-prone regions in the high latitudes of the Northern Hemisphere, and the spatiotemporal variability of its wildfire activity and the underlying climatic drivers are of great importance for the regional environment and global climate change. Using fire data from Global Fire Emissions Database version 5 (GFED5), surface fuel datasets, atmospheric reanalysis data, and multiple climate indices during 2001 to 2020, this study systematically investigated the regional differences in wildfire activity across Siberia, the local meteorological controls, and the pathways of large-scale teleconnection influence. According to the spatial distribution of wildfire occurrence, fuel type, and seasonal fire regime, Siberia was divided into three subregions, namely Western Siberia (WS), Eastern Siberia (ES), and the Far East (FE). Among them, WS (West Siberia) exhibits active spring wildfires, primarily concentrated in April–May. The rapid drying of herbaceous vegetation following early snowmelt provides favorable conditions for wildfire ignition. Over the past 20 years, the burned area in this region has shown pronounced inter‑annual variability, with no clear long‑term trend. The main fuel types consist of temperate grasslands and the dried herbaceous layer in the forest‑steppe ecotone. The FE (Far East) region is characterized by notably high‑intensity wildfires that accumulate seasonally, with a fire season spanning from late spring to autumn. This area is dominated by closed boreal forest as the primary fuel source, and its high biomass accumulation makes it a key contributor to carbon emissions across Siberia. In contrast, ES (East Siberia), located at high latitudes (approximately 60°–70°N), experiences a summer fire season (July–August). Sparse boreal forest and organic soil layers regulated by permafrost degradation serve as the main fuel types. Against the backdrop of permafrost degradation and northward vegetation expansion, this region has shown a marked increase in both burned area and carbon emissions in recent years, accompanied by a clear poleward and tundra‑ward expansion of fire activity.Correlation analysis between local meteorological factors and burned area within each region indicates that hot‑dry conditions are a prevalent controlling factor, albeit with distinct circulation characteristics and influencing mechanisms across the three subregions. For the ES region, interannual variations in burned area are jointly controlled by high temperature and moisture stress. The dominant circulation pattern is characterized by anomalous blocking highs that enhance subsidence warming and suppress moisture transport from the Atlantic and Arctic Oceans, thereby reducing soil moisture and near‑surface relative humidity, which intensifies drought and elevates fire risk. In the WS region, wildfire occurrence is primarily driven by moisture deficit, with relative humidity (correlation coefficient r = 0.77) exerting a stronger influence than temperature anomalies. Anomalous high‑pressure systems not only increase surface evaporative demand but also accelerate the desiccation of fine fuels, indicating that fuel moisture is a critical limiting factor for spring wildfire ignition. In the FE region, spring wildfires are most active and are mainly associated with compound hot and dry conditions. Persistent positive geopotential height anomalies combined with warm advection from lower latitudes provide favorable circulation backgrounds for fire occurrence.Large-scale climate modes exert significant modulation on wildfire activity in different parts of Siberia by modulating meteorological factors, with clear regional contrasts and cross-seasonal lagged effects. In general, fire risk in ES and the FE is jointly influenced by North Pacific Sea surface temperature (SST) anomalies and climatic modes over the middle to high latitudes. Specifically, the Pacific Decadal Oscillation (PDO) plays a dominant role, while the Polar Eurasia pattern (POL) and the Pacific North American pattern (PNA) act synergistically. Interestingly, the response mechanisms differ substantially between the two regions(The correlation coefficient between the spring PDO index and summer moisture in the ES region is 0.47, while the correlation coefficient between the winter PDO index and spring moisture in the FE region is -0.47.). In ES, enhanced cyclonic circulation, intensified upward motion, and increased cold and moist air intrusion create cool and wet conditions that suppress fire activity. In contrast, the FE is more strongly controlled by an anticyclonic ridge, where subsidence warming, enhanced solar radiation, and stronger warm and dry advection collectively promote surface warming and drying and thus increase fire risk. This contrast is related not only to differences in the peak fire season between the two regions but also to their latitudinal positions, which place them under opposite phases of the teleconnection wave trains associated with the PDO, POL, and PNA, thereby producing distinct local circulation backgrounds and wildfire responses. Wildfire risk in WS is mainly affected by modes featured at lower latitudes, especially the SST anomalies over eastern tropical Pacific (represented by Niño1+2). It is shown that summertime near-surface humidity, vapor pressure deficit, and fuel dryness in WS, the factors dominant in mediating local fire, are potentially influenced by warmer eastern tropical Pacific through cross-seasonal teleconnections. All major climate modes exhibit lead signals of about three months for regional fire risk, suggesting the seasonal predictability of wildfire risk in Siberia. These findings provide scientific basis for wildfire risk monitoring, seasonal forecasting, and fire early warning in Siberia, and may also offer insights applicable to other high-latitude regions.

Grantor dc:publisher

Helsingin yliopisto

Year dc:date.issued

2026

Author dc:creator

• Zou, Bowen

• wildfires
• Siberia
• regional heterogeneity
• atmospheric circulation
• teleconnection

Statement dc:rights

• In Copyright 1.0

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/10138/634357

OAI identifier oai:identifier

oai:helda.helsinki.fi:10138/634357