Interannual impact of the Victoria mode on the winter-spring surface air temperature over Eurasia and North America

Abstract

Variations of the Victoria mode (VM) have received considerable attention due to their profound impacts on the climate systems in the pan-North Pacific. However, works about its impact on surface air temperature (SAT) variability over Eurasia and North America, which may be responsible for extreme weather and climate events, are limited. Here we show a significant positive and negative relationship between the VM and the winter-spring SAT anomalies over mid-to-high-latitude east-central Eurasia (MEE) and eastern North America (ENA), respectively. A local energy budget analysis shows that the contribution of the surface heat fluxes associated with the VM to the SAT anomalies is confined mainly to MEE and may not explain the formation of SAT anomalies over ENA. Furthermore, VM-induced anomalous atmospheric circulations play a crucial role in the formation of notable SAT anomalies. The positive (negative) VM is linked to negative (positive) precipitation and upper-tropospheric wind convergence (divergence) anomalies over the western North Pacific, which contribute to positive (negative) Rossby wave source (RWS) anomalies near the East Asian westerly jet core. These RWS anomalies act as disturbances that propagate eastward, exciting a wave train-like pattern. The high-level positive and negative geopotential height anomalies of the Rossby wave dominate MEE and ENA, respectively, leading to the variation in SAT anomalies. These results could advance our understanding of the relationship between the VM and SAT over the Northern Hemisphere and inspire us to pay more attention to the VM climate impacts.