Summer 2010 saw two simultaneous extremes linked by an atmospheric wave train: a record-breaking heatwave in Russia and severe floods in Pakistan. Here, we study this wave event using a large ensemble climate model experiment. First, we show that the circulation in 2010 reflected a recurrent wave train connecting the heatwave and flooding events. Second, we show that the occurrence of the wave train is favored by three drivers: (1) 2010 sea surface temperature anomalies increase the probability of this wave train by a factor 2-to-4 relative to the model’s climatology, (2) early-summer soil moisture deficit in Russia not only increases the probability of local heatwaves, but also enhances rainfall extremes over Pakistan by forcing an atmospheric wave response, and (3) high-latitude land warming favors wave-train occurrence and therefore rainfall and heat extremes. These findings highlight the complexity and synergistic interactions between different drivers, reconciling some seemingly contradictory results from previous studies.
Bibliographical noteFunding Information:
This work was supported by the German Federal Ministry of Education and Research (BMBF), grants 01LP1611A (G.D.C., E.R. and D.C.) and 01LP1901E (E.R.); the JPI Climate/JPI Oceans project ROADMAP (grant no. 01LP2002B) (G.D.C.); the Netherlands Organization for Scientific Research (NWO), grant 016.Vidi.171011 (D. C.); the National Science Foundation NSF AGS-1934358 (K.K.); the Belmont-Forum funded GOTHAM project (NE/P006779/1) (S.S., D.W., and S.O.) and the UK NERC National Centre for Atmospheric Science (S.O.). We would like to thank the Met Office Hadley Centre PRECIS team for their technical and scientific support for the development and application of weather@Home. Finally, we would like to thank all of the volunteers who have donated their computing time to climatepredic-tion.net.
© 2021, The Author(s).