Impact of North Atlantic Sea Surface Temperature Anomaly on Interannual Variability of Summer Atmospheric Heat Source over the Tibetan Plateau

Abstract The summer atmospheric heat source (AHS) over the Tibetan Plateau (TP), modulated by the midlatitude westerlies and Asian summer monsoon, exerts a crucial influence on regional and global atmospheric circulation and climate change. Previous studies have predominantly focused on the impact of low-latitude tropical ocean–atmosphere forcing signals on the summer AHS over the TP. Notably, the North Atlantic (NA) sea surface temperature anomaly (SSTA), as an upstream signal in mid- and high latitudes, can also significantly affect the summer AHS over the TP by stimulating atmospheric teleconnection wave trains, while the mechanisms and contributions remain unclear. This study explores the interannual variation of the summer AHS over the TP and its correlation with concurrent NA SSTA. The results indicate the NA tripole (NAT)-like SSTA pattern contributes about 20% to the interannual variability of the summer AHS over the southeastern TP. Specifically, when the NAT-like SSTA pattern is in a negative phase (meridional positive–negative–positive pattern), it triggers a teleconnection wave train propagating from west to east, culminating in the positive AHS anomaly over the southeastern TP. Further analysis indicates the presence of anomalous vertical ascending motions associated with the wave train over the southeastern TP. When coupled with the convergence belt of water vapor, it is beneficial to the precipitation in this region. The release of condensation latent heat subsequently emerges as a significant contributor to the positive AHS anomaly. Finally, numerical simulation experiments also validate this impact process. This study elucidates the physical mechanism through which NA SSTA affects the interannual variability of the AHS over the TP in summer, providing a scientific basis for climate prediction and disaster management in the region.