Asymmetrical Trends of Burned Area Between Eastern and Western Siberia Regulated by Atmospheric Oscillation

Abstract

Wildfires in Siberian cause organic carbon released from Arctic ecosystems to the atmosphere, which further enhances greenhouse effects. However, the trends of Siberian wildfires and their mechanisms are not well understood. We show that the burned fraction trends were opposite in the eastern and western Siberia. The contrasting changes are explained by vapor pressure deficit and soil moisture inferring atmospheric and ground aridity conditions, respectively. The difference in aridity change in the eastern and western Siberia is regulated by increased positive phase of Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO), which leads to reduced moisture transport to the east but increased transport to the west from the North Atlantic and Arctic Ocean mainly during May–August. The growing trend of positive phase of AO and NAO will continuously lead to the asymmetrical trends of aridity condition, which could enhance wildfire in the eastern Siberia.