The role of Tibetan Plateau heat source in shaping the interdecadal Eurasian dual high‑temperature mode

Based on multi‑source reanalysis and numerical simulations, this study investigates the interdecadal variability of summer near‑surface air temperature over Eurasia and the role of the Tibetan Plateau atmospheric heat source (TPQ 1 ). A pronounced dual high temperature mode is identified, characterized by two synchronous warming centers located in Eastern Europe and the region from the northern Tibetan Plateau to Lake Baikal. This mode dominates the interdecadal variability in 2 m temperature, daily maximum temperature and hot days. Temporally, it shows a strong phase in the 1960s–1970s, a weakening period thereafter, and renewed intensification from the early twenty-first century onward. The TPQ 1 , particularly over the central southern Plateau, displays a similar “positive–negative–positive” evolution. Enhanced TPQ 1 converts available potential energy to divergent kinetic energy near 200 hPa, strengthening upper‑level outflow and driving a trans‑Eurasian thermal vertical circulation. Ascending motion over the Plateau couples with compensatory subsidence over Eastern Europe and Central Asia–Mongolia, where negative energy conversion and adiabatic warming sustain quasi‑barotropic high‑pressure anomalies. Reduced cloud cover and increased downward shortwave radiation further amplify surface warming. Both the CESM2 pre-industrial control simulation and AGCM sensitivity experiments, without anthropogenic forcing or with only enhanced TP heating, well reproduce the observed dual high-temperature mode, quasi-barotropic circulation, and thermal vertical circulation. Among 45 ensemble members, 30 show a positive correlation with observations. The results are meaningful for deepening our understanding of the thermal effect of the TP and its global responses. These findings also suggest that the influence of internal variability on the anomalous high temperature over the Northern Hemispheric midlatitudes is non‑negligible.