Kim et al. (2026) Eurasian Summertime Intraseasonal Oscillation and its impact on compound hot-dry extremes

Identification

• Journal: npj Climate and Atmospheric Science
• Year: 2026
• Date: 2026-09-15
• Authors: Jeong‐Hun Kim, Yu Kosaka, Joowan Kim
• DOI: 10.1038/s41612-026-01549-8

Research Groups

• Research Center for Advanced Science and Technology, The University of Tokyo, Japan
• Department of Atmospheric Sciences, Kongju National University, Gongju, Republic of Korea

Short Summary

This study identifies the Eurasian Summertime Intraseasonal Oscillation (ESISO) as a distinct mid- to high-latitude contributor to Eurasian compound hot-dry extremes. The ESISO exerts phase-dependent control on the probability of compound hot-dry extremes across the Eurasian continent.

Objective

• Investigate the relationship between the Eurasian Summertime Intraseasonal Oscillation (ESISO) and compound hot-dry extremes over the Eurasian continent.
• Examine the future changes in ESISO structure and occurrence frequency under +4 K warming.

Study Configuration

• Spatial Scale: Continental-scale, focusing on the Eurasian region.
• Temporal Scale: Intraseasonal variability, with a dominant period of approximately 10–60 days.

Methodology and Data

• Models used: JRA-3Q reanalysis and d4PDF large-ensemble climate simulations (100-member historical and 90-member +4 K experiments).
• Data sources: Satellite, observation, and reanalysis data from various sources, including ERA-5 and MERRA-2.

Main Results

• The ESISO is identified as a coherent, propagating intraseasonal mode over the Eurasian continent.
• The ESISO exerts phase-dependent control on compound hot-dry extremes across the Eurasian continent.
• Under +4 K warming, the frequency of intense ESISO events increases significantly in most phases.

Contributions

• This study provides new insights into the dynamics and impacts of the ESISO on Eurasian compound hot-dry extremes.
• The findings complement existing tropical and subtropical frameworks for understanding compound extreme probability on subseasonal timescales.

Funding

• This research was supported by the National Science Foundation (NSF) under grant number NSF-AGS 1551119.
• Additional funding was provided by the Japan Society for the Promotion of Science (JSPS) under grant number JSPS-KAKENHI JP16H06284.

Citation

@article{Kim2026Eurasian,
  author = {Kim, Jeong‐Hun and Kim, Jeong‐Hun and Kosaka, Yu and Kim, Joowan and Kim, Joowan},
  title = {Eurasian Summertime Intraseasonal Oscillation and its impact on compound hot-dry extremes},
  journal = {npj Climate and Atmospheric Science},
  year = {2026},
  doi = {10.1038/s41612-026-01549-8},
  url = {https://doi.org/10.1038/s41612-026-01549-8}
}