The northern Eurasia is a region heavily affected by the Arctic polar vortex (APV). Understanding the vegetation responses to anomalous APV in this region is important for dealing with climate change. In this study, we investigated the impacts and mechanism of the anomalous APV phases on the vegetation dynamics in the northern Eurasia. The larger and smaller APV phases correspond to almost opposite atmospheric circulation patterns which result in opposite vegetation responses. The decreased (increased) solar radiation, the enhanced (weakened) northerly winds, together with the decreased (increased) water vapor divergence, caused the decreasing (increasing) of the air temperature, increasing (decreasing) of the precipitation and soil moisture in the study area during the larger (smaller) APV phase. The response of vegetation growth to the APV depends on climate change and vegetation sensitivity to it. In most parts of the study area, vegetation growth was positively associated with air temperature, and hence, vegetation was suppressed (promoted) during the larger (smaller) APV phase. In the northeast of the Caspian Sea (NCS), vegetation growth was sensitive to precipitation. Therefore, the increased (decreased) soil moisture in summer and autumn were responsible for the promoted (suppressed) vegetation growth during the larger (smaller) APV phase.
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