Sensitivity of the Southern Hemisphere Wintertime Teleconnection to the Location of ENSO Heating

Journal Article · Wed Mar 15 00:00:00 EDT 2023 · Journal of Climate

DOI:https://doi.org/10.1175/jcli-d-22-0159.1· OSTI ID:2424880

Gillett, Z. E. ^[1]; Hendon, H. H. ^[2]; Arblaster, J. M. ^[3]; Lin, H. ^[4]

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1. Univ. of New South Wales, Sydney, NSW (Australia)
2. Monash Univ., Melbourne, VIC (Australia); Bureau of Meteorology, Melbourne, VIC (Australia)
3. Monash Univ., Melbourne, VIC (Australia); National Center for Atmospheric Research (NCAR), Boulder, CO (United States)
4. Environment and Climate Change Canada, Dorval, QC (Canada)

The Southern Hemisphere extratropical atmospheric circulation response to anomalous convection in the tropical western and eastern Pacific Ocean is distinctly different. The response to westward-located heating has a meridional dipole in the South Pacific with large zonal scale and appears unable to be interpreted simply as a stationary Rossby wave train that disperses poleward and eastward from a tropical source like the meridionally arched response to eastward-located heating. Here, this study investigates the cause of this asymmetry by examining the daily evolution of the response to suddenly switching on steady diabatic heating over a western and central/eastern equatorial Pacific location using large-ensemble integrations from the Community Atmosphere Model version 5. We focus on the austral winter months when the subtropical jet supports the development of an effective Rossby wave source in the subtropical westerlies and acts as a waveguide. We show that the subtropical jet strongly influences the height response to the western tropical Pacific heating, promoting prominent zonal circumglobal propagation. Development of a transient eddy feedback in the extratropical storm track after approximately 10 days appears to play a primary role in establishing the time-mean response, which we test through comparison with similar experiments conducted using a simplified linear model. Conversely, the height anomalies for eastern tropical Pacific heating, farther away from the subtropical jet core, have larger meridional propagation, dispersing in a typical Hoskins–Karoly manner into the Southern Hemisphere extratropics, while the transient eddy feedback plays a secondary role for the establishment of the steady response.

• Research Organization: National Center for Atmospheric Research (NCAR), Boulder, CO (United States)
• Sponsoring Organization: ARC Centre of Excellence for Climate Extremes; National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER)
• OSTI ID: 2424880
• Journal Information: Journal of Climate, Journal Name: Journal of Climate Journal Issue: 8 Vol. 36; ISSN 1520-0442; ISSN 0894-8755
• Publisher: American Meteorological Society
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
El Nino
Meteorology & Atmospheric Sciences
Pacific Ocean
Rossby waves
eddies
jets
teleconnections