Linking subtropical jet persistence to early-spring heat events in South and West Asia

Banerjee, A., Koehl, A., Hunt, K. ORCID: https://orcid.org/0000-0003-1480-3755 and Stammer, D. (2026) Linking subtropical jet persistence to early-spring heat events in South and West Asia. Environmental Research: Climate. ISSN 2752-5295 doi: 10.1088/2752-5295/ae5417 (In Press)

Abstract/Summary

Early-spring heat extremes over West and South Asia have intensified over recent years. However, there is limited understanding of the large-scale atmospheric factors linked to their occurrence during February–April in this region. Here, we analyze 200-hPa zonal wind anomalies (1990–2023) from the ERA5 reanalysis using a neural network–based Self-Organizing Map clustering method. We identify two dominant jet regimes and their associated persistent atmospheric states over Eurasia that seem to be involved in causing the early-spring heat events. We find that these jet states are connected to preferred atmospheric weather regimes in the North Atlantic. Composite analyses show that persistent jet episodes are characterized by a meridional shift of the subtropical jet, mid-to-upper tropospheric ridging, and reduced moisture transport. Persistent jet years also show a seasonal decrease in western disturbance activity, limiting synoptic cooling. Altogether, these processes highlight a dynamical teleconnection in which persistent jet states precondition the downstream regional atmosphere over West and South Asia for heat extremes, by modulating moisture transport and transient weather systems. Our findings suggest that persistent subtropical jet states represent a crucial large-scale precursor of high-temperature anomalies over West and South Asia.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/129053
Identification Number/DOI	10.1088/2752-5295/ae5417
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > NCAS Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	IOP Science
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