Changes in fire-season burned area in northeastern China regulated by tropical North Atlantic variability

Abstract

Mapping and monitoring regional fire activity are essential to understand their responses to human activities and climate change. Here we use multiple sources of observations, reanalysis data, and model simulations to examine the responses of fire activity to climate change over northeastern China in the past two decades. We detected significant positive burned area (BA) trends in this region since 2003 during spring and much stronger interannual variations in BA in the last decade. We then separated the study region into cropland and natural vegetation and found that the increasing BA trends come mainly from agricultural burning. Our results also show that temperature is the dominant driver for BA variations in natural vegetation, whereas agricultural burning is influenced by precipitation, although human activities largely contribute to BA variations due to farming practices and land use and management. Our results further suggest that tropical North Atlantic (TNA) sea surface temperatures (SST) variability regulates the fire weather conditions (temperature and precipitation) in northeastern China through the Rossby wave train from the tropical Atlantic to the Eurasian continent. The cooling of TNA SST since 2010 could induce an anomalous anticyclonic circulation around Northeast Asia, leading to sinking motion and divergence in the region and resulting in reduced precipitation and warm temperatures. Thus, the co-occurrence of warm and dry anomalies has led to more frequent burning since the 2010s. Our study not only detects recent BA variations in northeastern China but also provides further evidence for the remote impact of TNA variability on recent BA and climate variations over the region.

Keywords

• burned area
• northeastern China
• fire weather conditions
• tropical North Atlantic