The evolution of Pacific-North American teleconnection during the past 250 million years

The Pacific-North American (PNA) teleconnection is one of the most crucial climate modes in the current climate. It is well known that the PNA is related to the ENSO variability, and it has a significant influence on North American climate. Whereas, the traditional physical mechanisms about the PNA is probably not applicable for the deep-time paleoclimate. During the past 250 million years, climate variabilities are strongly structured by the evolution of land-sea distribution, CO₂ forcing, and solar radiation. In this work, we use the Community Earth System Model (CESM) version 1.2.2 to investigate the changes of PNA every 10 million years. The deep-time simulation provides a new way to understand the nature of PNA and the related physical mechanisms. We found that the spatial distribution of the PNA-like mode is closely related to the land-sea distribution. And the combination effect from atmospheric circulation and the thermal condition is proved to be important to modulate the evolution of PNA.