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Title: Mechanisms causing east Australian spring rainfall differences between three strong El Niño events

Abstract

Strong El Niño events have had significant impacts on society through their association with extreme events, such as droughts and floods. However, questions remain as to the robustness of strong El Niño events in forcing regional climate variability. The strong 1982, 1997 and 2015 El Niño events were of similar type and strength, but in eastern Australia they were associated with differing spring rainfall anomaly magnitudes and patterns. To understand these differences, we first determined the most important processes for teleconnecting the El Niño signal to east Australian spring rainfall using historical relationships with winds and sea level pressure. Then, using a 60-member atmospheric model ensemble, we estimated the influence of sea surface temperatures (SSTs) on Australian atmospheric circulation and rainfall during these three El Niño events relative to internal variability. We found that the different east Australian spring rainfall anomalies for each of the three El Niño events are best explained by differences in the strength of the meridional wind component of the regional circulation. All three El Niño events exhibited a positive sea level pressure anomaly to the south of Australia, which was associated with rainfall deficits along the southeast Australian coast. The experiments indicate the regional atmosphericmore » circulation and rainfall differences were forced by SSTs during spring of 1982 and 1997, with their influence on the circulation in 2015 remaining unclear. We also show that SSTs adjacent to Australia further contributed to the modelled rainfall differences mainly by regulating moisture availability.« less

Authors:
ORCiD logo [1];  [2];  [3];  [4];  [5]; ORCiD logo [6]
  1. Monash Univ., Melbourne, VIC (Australia). Earth, Atmosphere and Environment, and ARC Centre of Excellence for Climate Systems Science; Commonwealth Scientific and Industrial Research Organization (CSIRO), Aspendale, VIC (Australia)
  2. Monash Univ., Melbourne, VIC (Australia). Earth, Atmosphere and Environment and ARC Centre of Excellence for Climate Extremes; National Center for Atmospheric Research, Boulder, CO (United States)
  3. Monash Univ., Melbourne, VIC (Australia). Earth, Atmosphere and Environment; Commonwealth Scientific and Industrial Research Organization (CSIRO), Aspendale, VIC (Australia)
  4. Monash Univ., Melbourne, VIC (Australia). ARC Centre of Excellence for Climate Systems Science
  5. Monash Univ., Melbourne, VIC (Australia). Earth, Atmosphere and Environment
  6. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1532618
Report Number(s):
LLNL-JRNL-768502
Journal ID: ISSN 0930-7575; 958744
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Climate Dynamics
Additional Journal Information:
Journal Name: Climate Dynamics; Journal ID: ISSN 0930-7575
Publisher:
Springer-Verlag
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Precipitation; Extreme El Niño; Super El Niño; Climate variability

Citation Formats

van Rensch, Peter, Arblaster, Julie, Gallant, Ailie J. E., Cai, Wenju, Nicholls, Neville, and Durack, Paul J. Mechanisms causing east Australian spring rainfall differences between three strong El Niño events. United States: N. p., 2019. Web. doi:10.1007/s00382-019-04732-1.
van Rensch, Peter, Arblaster, Julie, Gallant, Ailie J. E., Cai, Wenju, Nicholls, Neville, & Durack, Paul J. Mechanisms causing east Australian spring rainfall differences between three strong El Niño events. United States. doi:10.1007/s00382-019-04732-1.
van Rensch, Peter, Arblaster, Julie, Gallant, Ailie J. E., Cai, Wenju, Nicholls, Neville, and Durack, Paul J. Fri . "Mechanisms causing east Australian spring rainfall differences between three strong El Niño events". United States. doi:10.1007/s00382-019-04732-1.
@article{osti_1532618,
title = {Mechanisms causing east Australian spring rainfall differences between three strong El Niño events},
author = {van Rensch, Peter and Arblaster, Julie and Gallant, Ailie J. E. and Cai, Wenju and Nicholls, Neville and Durack, Paul J.},
abstractNote = {Strong El Niño events have had significant impacts on society through their association with extreme events, such as droughts and floods. However, questions remain as to the robustness of strong El Niño events in forcing regional climate variability. The strong 1982, 1997 and 2015 El Niño events were of similar type and strength, but in eastern Australia they were associated with differing spring rainfall anomaly magnitudes and patterns. To understand these differences, we first determined the most important processes for teleconnecting the El Niño signal to east Australian spring rainfall using historical relationships with winds and sea level pressure. Then, using a 60-member atmospheric model ensemble, we estimated the influence of sea surface temperatures (SSTs) on Australian atmospheric circulation and rainfall during these three El Niño events relative to internal variability. We found that the different east Australian spring rainfall anomalies for each of the three El Niño events are best explained by differences in the strength of the meridional wind component of the regional circulation. All three El Niño events exhibited a positive sea level pressure anomaly to the south of Australia, which was associated with rainfall deficits along the southeast Australian coast. The experiments indicate the regional atmospheric circulation and rainfall differences were forced by SSTs during spring of 1982 and 1997, with their influence on the circulation in 2015 remaining unclear. We also show that SSTs adjacent to Australia further contributed to the modelled rainfall differences mainly by regulating moisture availability.},
doi = {10.1007/s00382-019-04732-1},
journal = {Climate Dynamics},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {3}
}

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This content will become publicly available on March 22, 2020
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