Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

How Sensitive are the Pacific-North Atlantic Teleconnections to the Position and Intensity of El Nino Related Warming

TitleHow Sensitive are the Pacific-North Atlantic Teleconnections to the Position and Intensity of El Nino Related Warming
Publication TypeJournal Article
Year of Publication2015
AuthorsTaschetto, A S., Rodrigues R R., Meehl G A., McGregor S, and England M H.
JournalClimate Dynamics
Volume46
Pages1841-1860
Abstract / Summary

The atmospheric teleconnections associated with the Eastern Pacific El Niño and El Niño Modoki events onto the tropical Atlantic Ocean are investigated. The Eastern Pacific El Niños drive significant warming of the tropical North Atlantic basin during boreal spring after its peak via the atmospheric bridge and tropospheric temperature mechanisms. However, the tropical Atlantic does not show a robust response to El Niño Modoki events. Here our results suggest that the preconditioning of the tropical North Atlantic sea surface temperature (SST) anomalies in boreal winter plays an important role in the following season, not only during Eastern Pacific El Niños but also during El Niño Modoki events. Additionally, we examine three other factors that could explain potential differences in the tropical Atlantic teleconnections from El Niño Modoki and Eastern Pacific El Niño events: (1) The distant location of the maximum SST warming in the Pacific; (2) The weak warming associated with this pattern; and (3) The SST pattern including a cooling in the eastern Pacific. Using numerical experiments forced with idealised SST in the equatorial Pacific, we show that the location of the El Niño Modoki SST warming during its mature phase could be favourable for exciting atmospheric teleconnections in boreal winter but not in the following spring season due to the seasonal shift of the Inter-Tropical Convergence Zone that modulates deep convection over the anomalous SST. This demonstrates the importance of the mean seasonal atmospheric circulation in modulating the remote teleconnections from the central-western Pacific warming in the model. However, it is suggested here that the cooling in the eastern Pacific associated with El Niño Modoki counteracts the atmospheric response driven by the central western Pacific warming, generating a consequent weaker connection to the tropical Atlantic compared to the stronger link during Eastern Pacific El Niño events. Finally we show that the modeled Pacific–tropical Atlantic teleconnections to an eastern Pacific warming depends strongly on the underlying seasonal cycle of SST.

URLhttps://link.springer.com/article/10.1007%2Fs00382-015-2679-x
DOI10.1007/s00382-015-2679-x
Journal: Climate Dynamics
Year of Publication: 2015
Volume: 46
Pages: 1841-1860
Publication Date: 06/2015

The atmospheric teleconnections associated with the Eastern Pacific El Niño and El Niño Modoki events onto the tropical Atlantic Ocean are investigated. The Eastern Pacific El Niños drive significant warming of the tropical North Atlantic basin during boreal spring after its peak via the atmospheric bridge and tropospheric temperature mechanisms. However, the tropical Atlantic does not show a robust response to El Niño Modoki events. Here our results suggest that the preconditioning of the tropical North Atlantic sea surface temperature (SST) anomalies in boreal winter plays an important role in the following season, not only during Eastern Pacific El Niños but also during El Niño Modoki events. Additionally, we examine three other factors that could explain potential differences in the tropical Atlantic teleconnections from El Niño Modoki and Eastern Pacific El Niño events: (1) The distant location of the maximum SST warming in the Pacific; (2) The weak warming associated with this pattern; and (3) The SST pattern including a cooling in the eastern Pacific. Using numerical experiments forced with idealised SST in the equatorial Pacific, we show that the location of the El Niño Modoki SST warming during its mature phase could be favourable for exciting atmospheric teleconnections in boreal winter but not in the following spring season due to the seasonal shift of the Inter-Tropical Convergence Zone that modulates deep convection over the anomalous SST. This demonstrates the importance of the mean seasonal atmospheric circulation in modulating the remote teleconnections from the central-western Pacific warming in the model. However, it is suggested here that the cooling in the eastern Pacific associated with El Niño Modoki counteracts the atmospheric response driven by the central western Pacific warming, generating a consequent weaker connection to the tropical Atlantic compared to the stronger link during Eastern Pacific El Niño events. Finally we show that the modeled Pacific–tropical Atlantic teleconnections to an eastern Pacific warming depends strongly on the underlying seasonal cycle of SST.

DOI: 10.1007/s00382-015-2679-x
Citation:
Taschetto, AS, RR Rodrigues, GA Meehl, S McGregor, and MH England.  2015.  "How Sensitive are the Pacific-North Atlantic Teleconnections to the Position and Intensity of El Nino Related Warming."  Climate Dynamics 46: 1841-1860.  https://doi.org/10.1007/s00382-015-2679-x.