Multidecadal Variation in the Seasonal Predictability of Winter PNA and Its Sources

Based on reanalysis and ensemble hindcasts data, this work investigates the multidecadal variation in the seasonal predictability of the Pacific-North American (PNA) teleconnection pattern during the winter and its sources. The results show that at the two ends of the 20th century, the PNA is mostly driven by the El Nino-Southern Oscillation (ENSO), and a good seasonal prediction of the PNA is expected if models can accurately predict the PNA-ENSO relationship. During the middle 20th century, the PNA is not only driven by ENSO but also closely linked to the Pacific Decadal Oscillation through the air-sea coupling process in the extratropical North Pacific. Improvements in the seasonal prediction of the PNA require models to accurately predict both the PNA-ENSO relationship and the air-sea coupling in the northern extratropical Pacific.

Automated summary

This study investigates the seasonal predictability of the Pacific-North American (PNA) teleconnection pattern during winter and its drivers using reanalysis and ensemble hindcasts data. The results indicate that ENSO is the main driver of the PNA pattern at the ends of the 20th century, and accurate prediction of the PNA-ENSO relationship leads to good seasonal forecasts of the PNA. However, during the middle of the 20th century, the PNA is not only influenced by ENSO but also closely linked to the Pacific Decadal Oscillation through air-sea coupling in the northern extratropical Pacific. Improving seasonal predictions of the PNA requires accurate prediction of both the PNA-ENSO relationship and the air-sea coupling in the region.