Nonlinear precipitation response to El Niño and global warming in the Indo-Pacific

TitleNonlinear precipitation response to El Niño and global warming in the Indo-Pacific
Publication TypeJournal Article
Year of Publication2014
AuthorsChung, C. T. Y., Arblaster S. B., Rashid H. A., and Roff G. L.
JournalClimate Dynamics
Volume42
Number7-8
Pages1837-1856
Date Published04/2014
Abstract / Summary

Precipitation changes over the Indo-Pacific during El Niño events are studied using an Atmospheric General Circulation Model forced with sea-surface temperature (SST) anomalies and changes in atmospheric CO2 concentrations. Linear increases in the amplitude of the El Niño SST anomaly pattern trigger nonlinear changes in precipitation amounts, resulting in shifts in the location and orientation of the Intertropical Convergence Zone (ITCZ) and the South Pacific Convergence Zone (SPCZ). In particular, the maximum precipitation anomaly along the ITCZ and SPCZ shifts eastwards, the ITCZ shifts south towards the equator, and the SPCZ becomes more zonal. Precipitation in the equatorial Pacific also increases nonlinearly. The effect of increasing CO2 levels and warming SSTs is also investigated. Global warming generally enhances the tropical Pacific precipitation response to El Niño. The precipitation response to El Niño is found to be dominated by changes in the atmospheric mean circulation dynamics, whereas the response to global warming is a balance between dynamic and thermodynamic changes. While the dependence of projected climate change impacts on seasonal variability is well-established, this study reveals that the impact of global warming on Pacific precipitation also depends strongly on the magnitude of the El Niño event. The magnitude and structure of the precipitation changes are also sensitive to the spatial structure of the global warming SST pattern.

URLhttp://link.springer.com/article/10.1007%2Fs00382-013-1892-8
DOI10.1007/s00382-013-1892-8
Journal: Climate Dynamics
Year of Publication: 2014
Volume: 42
Number: 7-8
Pages: 1837-1856
Date Published: 04/2014

Precipitation changes over the Indo-Pacific during El Niño events are studied using an Atmospheric General Circulation Model forced with sea-surface temperature (SST) anomalies and changes in atmospheric CO2 concentrations. Linear increases in the amplitude of the El Niño SST anomaly pattern trigger nonlinear changes in precipitation amounts, resulting in shifts in the location and orientation of the Intertropical Convergence Zone (ITCZ) and the South Pacific Convergence Zone (SPCZ). In particular, the maximum precipitation anomaly along the ITCZ and SPCZ shifts eastwards, the ITCZ shifts south towards the equator, and the SPCZ becomes more zonal. Precipitation in the equatorial Pacific also increases nonlinearly. The effect of increasing CO2 levels and warming SSTs is also investigated. Global warming generally enhances the tropical Pacific precipitation response to El Niño. The precipitation response to El Niño is found to be dominated by changes in the atmospheric mean circulation dynamics, whereas the response to global warming is a balance between dynamic and thermodynamic changes. While the dependence of projected climate change impacts on seasonal variability is well-established, this study reveals that the impact of global warming on Pacific precipitation also depends strongly on the magnitude of the El Niño event. The magnitude and structure of the precipitation changes are also sensitive to the spatial structure of the global warming SST pattern.

DOI: 10.1007/s00382-013-1892-8
Citation:
Chung, CT, SB Arblaster, HA Rashid, and GL Roff.  2014.  "Nonlinear precipitation response to El Niño and global warming in the Indo-Pacific."  Climate Dynamics 42(7-8): 1837-1856.  https://doi.org/10.1007/s00382-013-1892-8.