Impacts of Cold SST Anomalies in the Subpolar North Atlantic on Summer Temperature Anomalies in Eurasia

Abstract Cold blobs are widely known as persistent cold anomalies in the upper ocean of subpolar North Atlantic (SPNA) operating on interannual time scales. Although their driving mechanisms and relationship with ocean circulation have been hotly debated, their downstream climate effects on Eurasia have received limited attention. This study investigates the possible impacts of the SPNA cold blob events on intraseasonal climate variations over the latitudes of Eurasia in boreal summer (June–August) based on statistical analyses and numerical experiments. Results show that the cold blob events can modulate the downstream climate anomalies effectively via atmospheric teleconnection, inducing an intraseasonal reversal of the 2-m temperature (T2m) over the mid–high latitudes of Eurasia. In particular, atmospheric circulation and precipitation anomalies related to the cold blobs trigger a wave train that originates in SPNA and Greenland and propagates across mid–high latitudes into eastern Eurasia, resulting in a tripole T2m pattern over northern Eurasia in June. Then, in August, the precipitation anomalies and Rossby wave sources are reversed in Greenland and the North Atlantic, potentially due to the local feedback of the cold blobs to the atmosphere. Consequently, an intraseasonal reversal of the tripole T2m pattern also occurs in northern Eurasia due to the propagation of Rossby wave energy. Our results provide a theoretical basis for comprehensively understanding the sources of planetary-scale anomalous temperature distributions in Eurasia.