Reconciling opposite trends in the observed and simulated equatorial Pacific zonal sea surface temperature gradient
Abstract The reasons for large discrepancies between observations and simulations, as well as for uncertainties in projections of the equatorial Pacific zonal sea surface temperature (SST) gradient, are controversial. We used CMIP6 models and large ensemble simulations to show that model bias and in...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2023-11-01
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| Series: | Geoscience Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s40562-023-00309-3 |
| _version_ | 1797452451075325952 |
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| author | Wenrong Bai Hailong Liu Pengfei Lin Xichen Li Fan Wang |
| author_facet | Wenrong Bai Hailong Liu Pengfei Lin Xichen Li Fan Wang |
| author_sort | Wenrong Bai |
| collection | DOAJ |
| description | Abstract The reasons for large discrepancies between observations and simulations, as well as for uncertainties in projections of the equatorial Pacific zonal sea surface temperature (SST) gradient, are controversial. We used CMIP6 models and large ensemble simulations to show that model bias and internal variabilities affected, i.e., strengthened, the SST gradient between 1981 and 2010. The underestimation of strengthened trends in the southeast trade wind belt, the insufficient cooling effect of eastern Pacific upwelling, and the excessive westward extension of the climatological cold tongue in models jointly caused a weaker SST gradient than the recent observations. The phase transformation of the Interdecadal Pacific Oscillation (IPO) could explain ~ 51% of the observed SST gradient strengthening. After adjusting the random IPO phase to the observed IPO change, the adjusted SST gradient trends were closer to observations. We further constrained the projection of SST gradient change by using climate models’ ability to reproduce the historical SST gradient intensification or the phase of the IPO. These models suggest a weakened SST gradient in the middle of the twenty-first century. |
| first_indexed | 2024-03-09T15:07:55Z |
| format | Article |
| id | doaj.art-843e79e51c4e40f7aec5d2be523d4232 |
| institution | Directory Open Access Journal |
| issn | 2196-4092 |
| language | English |
| last_indexed | 2024-03-09T15:07:55Z |
| publishDate | 2023-11-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Geoscience Letters |
| spelling | doaj.art-843e79e51c4e40f7aec5d2be523d42322023-11-26T13:31:54ZengSpringerOpenGeoscience Letters2196-40922023-11-0110111210.1186/s40562-023-00309-3Reconciling opposite trends in the observed and simulated equatorial Pacific zonal sea surface temperature gradientWenrong Bai0Hailong Liu1Pengfei Lin2Xichen Li3Fan Wang4State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of SciencesState Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of SciencesState Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of SciencesInternational Center for Climate and Environment Sciences (ICCES), Institute of Atmospheric Physics, Chinese Academy of SciencesKey Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of SciencesAbstract The reasons for large discrepancies between observations and simulations, as well as for uncertainties in projections of the equatorial Pacific zonal sea surface temperature (SST) gradient, are controversial. We used CMIP6 models and large ensemble simulations to show that model bias and internal variabilities affected, i.e., strengthened, the SST gradient between 1981 and 2010. The underestimation of strengthened trends in the southeast trade wind belt, the insufficient cooling effect of eastern Pacific upwelling, and the excessive westward extension of the climatological cold tongue in models jointly caused a weaker SST gradient than the recent observations. The phase transformation of the Interdecadal Pacific Oscillation (IPO) could explain ~ 51% of the observed SST gradient strengthening. After adjusting the random IPO phase to the observed IPO change, the adjusted SST gradient trends were closer to observations. We further constrained the projection of SST gradient change by using climate models’ ability to reproduce the historical SST gradient intensification or the phase of the IPO. These models suggest a weakened SST gradient in the middle of the twenty-first century.https://doi.org/10.1186/s40562-023-00309-3Equatorial Pacific zonal sea surface temperature gradientCMIP6Large ensemble simulationsModel biasInternal variabilitiesProjection |
| spellingShingle | Wenrong Bai Hailong Liu Pengfei Lin Xichen Li Fan Wang Reconciling opposite trends in the observed and simulated equatorial Pacific zonal sea surface temperature gradient Geoscience Letters Equatorial Pacific zonal sea surface temperature gradient CMIP6 Large ensemble simulations Model bias Internal variabilities Projection |
| title | Reconciling opposite trends in the observed and simulated equatorial Pacific zonal sea surface temperature gradient |
| title_full | Reconciling opposite trends in the observed and simulated equatorial Pacific zonal sea surface temperature gradient |
| title_fullStr | Reconciling opposite trends in the observed and simulated equatorial Pacific zonal sea surface temperature gradient |
| title_full_unstemmed | Reconciling opposite trends in the observed and simulated equatorial Pacific zonal sea surface temperature gradient |
| title_short | Reconciling opposite trends in the observed and simulated equatorial Pacific zonal sea surface temperature gradient |
| title_sort | reconciling opposite trends in the observed and simulated equatorial pacific zonal sea surface temperature gradient |
| topic | Equatorial Pacific zonal sea surface temperature gradient CMIP6 Large ensemble simulations Model bias Internal variabilities Projection |
| url | https://doi.org/10.1186/s40562-023-00309-3 |
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