Abstract
Heatwaves can have devastating impact on society and reliable early warnings at several weeks lead time are needed. Previous studies showed that north-Pacific sea surface temperatures (SST) can provide long-lead predictability for eastern US temperature, mediated by an atmospheric Rossby wave. The exact mechanisms, however, are not well understood. Here we analyze two different Rossby waves associated with temperature variability in western and eastern US, respectively. Causal discovery analyses reveal that both waves are characterized by positive ocean-atmosphere feedbacks at daily timescales. Only for the eastern US, a long-lead causal link from SSTs to the Rossby wave exists, which generates summer temperature predictability. We show that this SST forcing mechanism originates from the evolution of the winter-to-spring Pacific Decadal Oscillation (PDO). During pronounced winter-to-spring PDO phases (either positive or negative) eastern US summer temperature forecast skill more than doubles, providing a temporary window of enhanced long-lead predictability.
Original language | English |
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Article number | 18 |
Pages (from-to) | 1-11 |
Number of pages | 11 |
Journal | NPJ CLIMATE AND ATMOSPHERIC SCIENCE |
Volume | 5 |
DOIs | |
Publication status | Published - 15 Mar 2022 |
Bibliographical note
Funding Information:S.V. would like to thank dr. Giorgia Di Capua for the fruitful discussions on the experiment design and the anonymous reviewer who greatly helped to improve the clarity of the manuscript. The authors acknowledge funding from the Netherlands Organization for Scientific Research (NWO), project: 016.Vidi.171.011.
Publisher Copyright:
© 2022, The Author(s).
Funding
S.V. would like to thank dr. Giorgia Di Capua for the fruitful discussions on the experiment design and the anonymous reviewer who greatly helped to improve the clarity of the manuscript. The authors acknowledge funding from the Netherlands Organization for Scientific Research (NWO), project: 016.Vidi.171.011.