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In recent decades, an increase in the frequency of extreme events in early spring across Eurasia has resulted in significant impacts on crop yields and socio-economic development. However, the variations of March surface air temperature (SAT) over Eurasia and mechanisms are still unclear. This study aims to investigate the dominant mode of the March surface air temperature (SAT) over Eurasia during 1979–2022, and its relationship with sea surface temperature (SST) and sea ice concentration (SIC). The results reveal the prevalence of a dipole mode of the Eurasian SAT anomalies (SATAs) in March characterized by positive SATAs in northern (50°N–80°N) Eurasia and negative ones in southern (10°N–45°N) region. Further analyses demonstrate that this dipole mode of Eurasian SATAs shows significant relationships with a positive phase of the North Atlantic tripole SST anomalies (NAT SSTAs), as well as with the decline of Barents Sea SIC anomalies (SICAs). Associated with the NAT SSTAs and the Barents Sea SICAs during March, two Rossby wave trains propagate towards Eurasia through different ways, one is propagating eastwards from the mid-latitude of the North Atlantic to Eurasia, and another one spreads from the polar region to Eurasia. Modulated by these two wave trains, anomalous near-surface southwesterly (northeasterly) wind induces more (less) warm air towards northern Eurasia, while more (less) cloud emerges in southern Eurasia and causes less (more) solar radiation reaching southern Eurasia, leading to the dipole mode of the Eurasian SATAs in March. These results are further confirmed by numerical experiments from the version 5 of the Community Atmosphere Model forced by the above mentioned SSTAs and SICAs. • The main mode of March surface air temperature (SAT) distribution in Eurasia displays a north-south dipole pattern. • Two wave trains generated from mid-latitude and polar region respectively are closely related to this dipole SAT pattern. • The anomalies of the North Atlantic SST and the Barents Sea SIC can excite different wave trains modulating the Eurasian SAT. [ABSTRACT FROM AUTHOR]

Hot drought events often have great impacts on society, the ecosystem, and agriculture. Northeastern China (NEC) is the ganary of China, thus it is quite important to investigate the characteristics of summer hot drought event (SHDE) over NEC and find the possible mechanisms. Based on the observation and the reanalysis datasets, we found that the decline of Barents Sea ice (SICBS) in March is closely related to the occurrence of summer SHDE over NEC during 1997-2016. The decline of SICBS can lead to decrease of snow depth over the western Eurasia (SDWEA) in April. On the one hand, the decline of SDWEA in April can regulate the atmospheric circulation during May-June that lead to dry soil in Yangtze River valley and northern China regions, which is further linked to SHDE over NEC. On the other hand, both the decline of SICBS in March and the decrease of SDWEA in April favor the positive Polar/Eurasia teleconnection pattern and dry soil over NEC in JA, which provides favorable atmospheric circulation patterns for SHDE over NEC. All of these results can be verified by the simulations from the Community Earth System Model and the numerical experiments that based on the version 4 of Community Atmosphere Model. Consequently, the Barents Sea ice in March might be a potential predictor for the SHDE over NEC. [ABSTRACT FROM AUTHOR]