Abstract
Central Asia is prone to wildfires, but the relationship between wildfires and climatic factors in this area is still not clear. In this study, the spatiotemporal variation in wildfire activities across Central Asia during 1997–2016 in terms of the burned area (BA) was investigated with Global Fire Emission Database version 4s (GFED4s). The relationship between BA and climatic factors in the region was also analyzed. The results reveal that more than 90% of the BA across Central Asia is located in Kazakhstan. The peak BA occurs from June to September, and remarkable interannual variation in wildfire activities occurs in western central Kazakhstan (WCKZ). At the interannual scale, the BA is negatively correlated with precipitation (correlation coefficient r = −0.66), soil moisture (r = −0.68), and relative humidity (r = −0.65), while it is positively correlated with the frequency of hot days (r = 0.37) during the burning season (from June to September). Composite analysis suggests that the years in which the BA is higher are generally associated with positive geopotential height anomalies at 500 hPa over the WCKZ region, which lead to the strengthening of the downdraft at 500 hPa and the weakening of westerlies at 850 hPa over the region. The weakened westerlies suppress the transport of water vapor from the Atlantic Ocean to the WCKZ region, resulting in decreased precipitation, soil moisture, and relative humidity in the lower atmosphere over the WCKZ region; these conditions promote an increase in BA throughout the region. Moreover, the westerly circulation index is positively correlated (r = 0.53) with precipitation anomalies and negatively correlated (r = −0.37) with BA anomalies in the WCKZ region during the burning season, which further underscores that wildfires associated with atmospheric circulation systems are becoming an increasingly important component of the relationship between climate and wildfire.
Highlights
Wildfires are natural disasters around the world and have directly caused enormous losses in terms of human lives, social disturbances, and environmental damage in recent years [1]
This study suggests that positive temperature, negative precipitation, soil moisture, and relative humidity anomalies in the central Kazakhstan correlate with large wildfires, so they are the good indicators to predict the occurrence and spread of wildfires at seasonal and intraseasonal scales based on the lagged relations for antecedent meteorological factors, and to project the future fire weather and climate conditions
We found that more than 90% of the annual mean burned area over Central Asia is concentrated in Kazakhstan
Summary
Wildfires are natural disasters around the world and have directly caused enormous losses in terms of human lives, social disturbances, and environmental damage in recent years [1]. It is estimated that the global annual burned area exceeds 3.5 million square kilometers induced by natural and anthropogenic origins, and it is mainly distributed in central and northern Africa, northern Australia, the Amazon region of South America, Southeast Asia, and the midlatitude Eurasian region including Central Asia [2]. Prasad et al [10] indicated that the temperature and precipitation corresponding to the warmest season of the year are the major climatic factors for the occurrence of the wildfire in southern India. Chen et al [11] found that the burned area in the Amazon region of South America during the burning season (August–October) is closely correlated with sea surface temperature (SST), precipitation, evapotranspiration, and total water storage (TWS)
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