Asymmetric ENSO Forcing on the South Pacific Meridional Mode
Abstract The South Pacific Meridional Mode (SPMM) influences El Niño‐Southern Oscillation (ENSO) variability, but whether ENSO triggers SPMM remains unclear. We show that ENSO can induce an in‐phase SPMM event via atmospheric teleconnections, beginning in early boreal summer of the ENSO‐developing y...
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Wiley
2025-07-01
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| Series: | Geophysical Research Letters |
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| Online Access: | https://doi.org/10.1029/2025GL117165 |
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| author | Cheng Qi Fan Jia |
| author_facet | Cheng Qi Fan Jia |
| author_sort | Cheng Qi |
| collection | DOAJ |
| description | Abstract The South Pacific Meridional Mode (SPMM) influences El Niño‐Southern Oscillation (ENSO) variability, but whether ENSO triggers SPMM remains unclear. We show that ENSO can induce an in‐phase SPMM event via atmospheric teleconnections, beginning in early boreal summer of the ENSO‐developing year, with a negative asymmetry. Strong La Niña induces negative SPMM more effectively than El Niño induces positive SPMM, due to differences in ENSO teleconnections and their intensity. During boreal summer and fall of strong La Niña, intense transient eddy feedback reshapes the Pacific‐South America pattern into a South Pacific Oscillation‐like pressure dipole, strengthening trade winds and promoting negative SPMM growth, a process absent in El Niño. In boreal winter, stronger La Niña teleconnections sustain negative SPMM into spring. Half of the negative SPMM events co‐occur with negative North Pacific Meridional Mode, contributing to multi‐year La Niña development. These findings advance the understanding of SPMM and its impact on ENSO. |
| format | Article |
| id | doaj-art-92a08a8f3e3a4f05be9b502f76f10a13 |
| institution | Matheson Library |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geophysical Research Letters |
| spelling | doaj-art-92a08a8f3e3a4f05be9b502f76f10a132025-07-26T08:35:57ZengWileyGeophysical Research Letters0094-82761944-80072025-07-015213n/an/a10.1029/2025GL117165Asymmetric ENSO Forcing on the South Pacific Meridional ModeCheng Qi0Fan Jia1Key Laboratory of Ocean Observation and Forecasting and Key Laboratory of Ocean Circulation and Waves Institute of Oceanology Chinese Academy of Sciences Qingdao ChinaKey Laboratory of Ocean Observation and Forecasting and Key Laboratory of Ocean Circulation and Waves Institute of Oceanology Chinese Academy of Sciences Qingdao ChinaAbstract The South Pacific Meridional Mode (SPMM) influences El Niño‐Southern Oscillation (ENSO) variability, but whether ENSO triggers SPMM remains unclear. We show that ENSO can induce an in‐phase SPMM event via atmospheric teleconnections, beginning in early boreal summer of the ENSO‐developing year, with a negative asymmetry. Strong La Niña induces negative SPMM more effectively than El Niño induces positive SPMM, due to differences in ENSO teleconnections and their intensity. During boreal summer and fall of strong La Niña, intense transient eddy feedback reshapes the Pacific‐South America pattern into a South Pacific Oscillation‐like pressure dipole, strengthening trade winds and promoting negative SPMM growth, a process absent in El Niño. In boreal winter, stronger La Niña teleconnections sustain negative SPMM into spring. Half of the negative SPMM events co‐occur with negative North Pacific Meridional Mode, contributing to multi‐year La Niña development. These findings advance the understanding of SPMM and its impact on ENSO.https://doi.org/10.1029/2025GL117165ENSOSouth Pacific meridional modemulti‐year La Niñateleconnection |
| spellingShingle | Cheng Qi Fan Jia Asymmetric ENSO Forcing on the South Pacific Meridional Mode Geophysical Research Letters ENSO South Pacific meridional mode multi‐year La Niña teleconnection |
| title | Asymmetric ENSO Forcing on the South Pacific Meridional Mode |
| title_full | Asymmetric ENSO Forcing on the South Pacific Meridional Mode |
| title_fullStr | Asymmetric ENSO Forcing on the South Pacific Meridional Mode |
| title_full_unstemmed | Asymmetric ENSO Forcing on the South Pacific Meridional Mode |
| title_short | Asymmetric ENSO Forcing on the South Pacific Meridional Mode |
| title_sort | asymmetric enso forcing on the south pacific meridional mode |
| topic | ENSO South Pacific meridional mode multi‐year La Niña teleconnection |
| url | https://doi.org/10.1029/2025GL117165 |
| work_keys_str_mv | AT chengqi asymmetricensoforcingonthesouthpacificmeridionalmode AT fanjia asymmetricensoforcingonthesouthpacificmeridionalmode |