Abstract
AbstractThe western North Pacific subtropical high (WNPSH), a prominent feature in the North Pacific during the boreal summer, exerts significant socioeconomic consequences by influencing hydrological extremes such as tropical cyclones, the Meiyu front, and summer heat waves over East Asia. Accurately forecasting the characteristics of the WNPSH over extended timescales is crucial, but subseasonal prediction in this specific context is still in its early stages due to the complex dynamics involved. In this study, we investigate the optimal predictable pattern of the WNPSH using linear stochastic dynamics. Our findings reveal that convection over the Philippine/South China Sea and Japan serves as key precursors, where a dipole vorticity pattern leads to maximum growth of the WNPSH on subseasonal timescales, providing a potential source of predictability. Additionally, we examine the role of optimal predictable patterns in the record-breaking 2020 WNPSH event, and we find that the cumulative effect of stochastic forcing helps explain the sustained features of this extreme case.
Publisher
Springer Science and Business Media LLC
Reference40 articles.
1. Yang, K. et al. Increased variability of the western pacific subtropical high under greenhouse warming. Proc. Natl. Acad. Sci. USA 119, e2120335119 (2022).
2. Zhou, Z.-Q., Xie, S.-P. & Zhang, R. Historic yangtze flooding of 2020 tied to extreme indian ocean conditions. Proc. Natl. Acad. Sci. USA 118, e2022255118 (2021).
3. Shaw, R. et al. Asia. In Pörtner, H. O.et al. (eds.) Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, book section 10 (Cambridge University Press, Cambridge, UK and New York, NY, USA, 2022).
4. Kang, S. M. & Polvani, L. M. The interannual relationship between the latitude of the eddy-driven jet and the edge of the hadley cell. J. Clim. 24, 563 – 568 (2011).
5. Scheff, J. & Frierson, D. M. W. Robust future precipitation declines in cmip5 largely reflect the poleward expansion of model subtropical dry zones. Geophys. Res. Lett. 39, L18704 (2012).