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Title: The role of the Southern Hemisphere semiannual oscillation in the development of a precursor to central and eastern Pacific Southern Oscillation warm events

Abstract

The semiannual oscillation (SAO) is a twice-yearly northward movement (in May-June-July (MJJ) and November-December-January (NDJ)) of the circumpolar trough of sea level pressure (SLP) in the Southern Hemisphere with effects throughout the troposphere. During MJJ the second harmonic of SLP, describing the SAO, has low values of SLP north of 50°S in the subtropical South Pacific, while the first harmonic, which is dominant over the Australian sector, increases to its peak. This once-a-year peak in negative SLP gradients (decreasing to the east) between Australia and the ocean to its east extends to the equatorial Pacific. Southern Oscillation warm events since 1950, with an intensification of this seasonal cycle, have had larger-amplitude SST anomalies in the eastern equatorial Pacific in MJJ and during the following mature phase in NDJ. Weak amplification of the seasonal cycle in MJJ tends to be followed by larger-amplitude SST anomalies in the central equatorial Pacific during NDJ.

Authors:
ORCiD logo [1];  [1]; ORCiD logo [2]
  1. National Center for Atmospheric Research (NCAR), Boulder, CO (United States)
  2. National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Monash Univ., Melbourne, VIC (Australia). School of Earth, Atmosphere and Environment
Publication Date:
Research Org.:
National Center for Atmospheric Research (NCAR), Boulder, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23). Climate and Environmental Sciences Division; National Science Foundation (NSF)
Contributing Org.:
National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States)
OSTI Identifier:
1473892
Grant/Contract Number:  
FC02‐97ER62402
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 44; Journal Issue: 13; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; semiannual oscillation; El Nino; seasonal cycle

Citation Formats

Meehl, Gerald A., van Loon, Harry, and Arblaster, Julie M. The role of the Southern Hemisphere semiannual oscillation in the development of a precursor to central and eastern Pacific Southern Oscillation warm events. United States: N. p., 2017. Web. doi:10.1002/2017GL073832.
Meehl, Gerald A., van Loon, Harry, & Arblaster, Julie M. The role of the Southern Hemisphere semiannual oscillation in the development of a precursor to central and eastern Pacific Southern Oscillation warm events. United States. doi:10.1002/2017GL073832.
Meehl, Gerald A., van Loon, Harry, and Arblaster, Julie M. Tue . "The role of the Southern Hemisphere semiannual oscillation in the development of a precursor to central and eastern Pacific Southern Oscillation warm events". United States. doi:10.1002/2017GL073832. https://www.osti.gov/servlets/purl/1473892.
@article{osti_1473892,
title = {The role of the Southern Hemisphere semiannual oscillation in the development of a precursor to central and eastern Pacific Southern Oscillation warm events},
author = {Meehl, Gerald A. and van Loon, Harry and Arblaster, Julie M.},
abstractNote = {The semiannual oscillation (SAO) is a twice-yearly northward movement (in May-June-July (MJJ) and November-December-January (NDJ)) of the circumpolar trough of sea level pressure (SLP) in the Southern Hemisphere with effects throughout the troposphere. During MJJ the second harmonic of SLP, describing the SAO, has low values of SLP north of 50°S in the subtropical South Pacific, while the first harmonic, which is dominant over the Australian sector, increases to its peak. This once-a-year peak in negative SLP gradients (decreasing to the east) between Australia and the ocean to its east extends to the equatorial Pacific. Southern Oscillation warm events since 1950, with an intensification of this seasonal cycle, have had larger-amplitude SST anomalies in the eastern equatorial Pacific in MJJ and during the following mature phase in NDJ. Weak amplification of the seasonal cycle in MJJ tends to be followed by larger-amplitude SST anomalies in the central equatorial Pacific during NDJ.},
doi = {10.1002/2017GL073832},
journal = {Geophysical Research Letters},
issn = {0094-8276},
number = 13,
volume = 44,
place = {United States},
year = {2017},
month = {6}
}

Journal Article:
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