Pacific Decadal Oscillation (PDO), one of the main internal decadal climate variabilities, has substantial impacts on climate and environment. The fact that the PDO is found to be a combination of multiple processes of different origins, such as stochastic forcing generated by local atmospheric noise, tropical-subtropical interactions via atmospheric and oceanic responses and ocean gyre dynamics, increases its uncertainty and complexity. Consequently, it is challenging to model and predict the PDO, especially the PDO phase transition.

Recently, a study conducted by the group led by Professor MA Zhuguo from Institute of Atmospheric Physics (IAP), cooperating with Sun Yat-sen University and Humboldt University of Berlin, proposed an innovation method climate network to detect the early warning signal of the PDO phase transition. From the 1890s to 2000s, the objectively detected early warning signal successfully forewarned all the six PDO phase transitions with an average of 6.5 years in advance, and only one false alarm sounded in the 1950s. As a result, the predictive skill of the PDO phase transition is significantly improved and close to the estimated upper limit of the predictability time (8-9 years).

This research further discovered that the cooperative behavior of climate network is the reason why the early warning of the PDO phase transition is detected from sea surface temperature successfully. Cooperative behavior is a phenomenon that more and more elements in a dynamical system display similar changes in temporal. "Due to the effect of cooperative behavior, the slight difference which is hard to be perceived individually can be easily detected macroscopically, which is helpful to reduce the influence of background noise," said the lead author Dr. LU Zhenghui from IAP.

"As a method driven by big data, climate network has shown a strong potential on climate research. Our research provides a new way for the prediction of the PDO phase transition, which may be applied to other major climate events," said Dr. YUAN Naiming, the corresponding author.

This work, published in Geophysical Research Letters, was supported by National Key R&D Program of China (2016YFA0600404), and National Natural Science Foundation of China (No. 41805065 and No. 41675088).

Reference
Lu, Z., Yuan, N., Yang, Q., Ma, Z., & Kurths, J. (2021). Early warning of the Pacific Decadal Oscillation phase transition using complex network analysis. Geophysical Research Letters, 48, e2020GL091674. https://doi.org/10.1029/2020GL091674

Media contact:

Ms. LIN Zheng, jennylin@mail.iap.ac.cn