Drivers of Future Indian Ocean Warming and Its Spatial Pattern in CMIP Models
Abstract Coupled Model Intercomparison Project phases 5 and 6 (CMIP5/6) projections display substantial inter‐model diversity in the future tropical Indian Ocean warming magnitude and spatial pattern. Here, we investigate the underlying physical mechanisms in 46 CMIP5/6 models using an upper‐ocean h...
Saved in:
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Wiley
2025-04-01
|
| Series: | Earth's Future |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2025EF006112 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849733630152146944 |
|---|---|
| author | S. Gopika K. Sadhvi J. Vialard V. Danielli S. Neetu M. Lengaigne |
| author_facet | S. Gopika K. Sadhvi J. Vialard V. Danielli S. Neetu M. Lengaigne |
| author_sort | S. Gopika |
| collection | DOAJ |
| description | Abstract Coupled Model Intercomparison Project phases 5 and 6 (CMIP5/6) projections display substantial inter‐model diversity in the future tropical Indian Ocean warming magnitude and spatial pattern. Here, we investigate the underlying physical mechanisms in 46 CMIP5/6 models using an upper‐ocean heat budget framework that separates surface net air‐sea flux changes into forcing and feedback components. The multi‐model mean (MMM) basin‐averaged warming is primarily driven by reduced evaporative cooling due to weaker surface winds related to reduction of both summer and winter monsoonal circulations and increased near‐surface relative humidity, with inter‐model variations in these parameters controlling warming diversity. The MMM warming pattern features a weakening equatorial gradient, resembling a positive Indian Ocean Dipole phase, and a strengthening interhemispheric gradient, both of which also dominate inter‐model spread. Ocean dynamics modulate the amplitude of the MMM IOD‐like pattern and its inter‐model variability through the Bjerknes feedback, which couples the zonal equatorial SST gradient, equatorial winds, and thermocline slope. Interactions with the tropical Pacific may further contribute to this response. Meanwhile, stronger climatological winds enhance evaporative cooling in the Southern Hemisphere, reducing warming there, and strengthening the MMM interhemispheric SST gradient. The diversity in this interhemispheric gradient is linked to variations in cross‐equatorial wind changes and their impact on latent heat flux forcing. This interhemispheric gradient strengthening is part of a broader pan‐tropical pattern, with similar features in the Pacific and Atlantic Oceans. These findings clarify the relative roles of thermodynamic processes and ocean dynamics in shaping future tropical Indian Ocean warming. |
| format | Article |
| id | doaj-art-f00210c8d9dc4ec0853e021ea5b3147d |
| institution | DOAJ |
| issn | 2328-4277 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | Wiley |
| record_format | Article |
| series | Earth's Future |
| spelling | doaj-art-f00210c8d9dc4ec0853e021ea5b3147d2025-08-20T03:07:58ZengWileyEarth's Future2328-42772025-04-01134n/an/a10.1029/2025EF006112Drivers of Future Indian Ocean Warming and Its Spatial Pattern in CMIP ModelsS. Gopika0K. Sadhvi1J. Vialard2V. Danielli3S. Neetu4M. Lengaigne5CSIR‐ National Institute of Oceanography Goa IndiaDigital University Kerala (DUK) Trivandrum IndiaLOCEAN/IPSL Sorbonne Universités (UPMC, Université Paris 06)‐CNRS‐IRD‐MNHN Paris FranceMARBEC IFREMER IRD University of Montpellier Montpellier FranceCSIR‐ National Institute of Oceanography Goa IndiaMARBEC IFREMER IRD University of Montpellier Montpellier FranceAbstract Coupled Model Intercomparison Project phases 5 and 6 (CMIP5/6) projections display substantial inter‐model diversity in the future tropical Indian Ocean warming magnitude and spatial pattern. Here, we investigate the underlying physical mechanisms in 46 CMIP5/6 models using an upper‐ocean heat budget framework that separates surface net air‐sea flux changes into forcing and feedback components. The multi‐model mean (MMM) basin‐averaged warming is primarily driven by reduced evaporative cooling due to weaker surface winds related to reduction of both summer and winter monsoonal circulations and increased near‐surface relative humidity, with inter‐model variations in these parameters controlling warming diversity. The MMM warming pattern features a weakening equatorial gradient, resembling a positive Indian Ocean Dipole phase, and a strengthening interhemispheric gradient, both of which also dominate inter‐model spread. Ocean dynamics modulate the amplitude of the MMM IOD‐like pattern and its inter‐model variability through the Bjerknes feedback, which couples the zonal equatorial SST gradient, equatorial winds, and thermocline slope. Interactions with the tropical Pacific may further contribute to this response. Meanwhile, stronger climatological winds enhance evaporative cooling in the Southern Hemisphere, reducing warming there, and strengthening the MMM interhemispheric SST gradient. The diversity in this interhemispheric gradient is linked to variations in cross‐equatorial wind changes and their impact on latent heat flux forcing. This interhemispheric gradient strengthening is part of a broader pan‐tropical pattern, with similar features in the Pacific and Atlantic Oceans. These findings clarify the relative roles of thermodynamic processes and ocean dynamics in shaping future tropical Indian Ocean warming.https://doi.org/10.1029/2025EF006112Indian OceanCMIPIOD like warming patternIndian Ocean basin average warmingair‐sea interactioninterhemispheric gradient |
| spellingShingle | S. Gopika K. Sadhvi J. Vialard V. Danielli S. Neetu M. Lengaigne Drivers of Future Indian Ocean Warming and Its Spatial Pattern in CMIP Models Earth's Future Indian Ocean CMIP IOD like warming pattern Indian Ocean basin average warming air‐sea interaction interhemispheric gradient |
| title | Drivers of Future Indian Ocean Warming and Its Spatial Pattern in CMIP Models |
| title_full | Drivers of Future Indian Ocean Warming and Its Spatial Pattern in CMIP Models |
| title_fullStr | Drivers of Future Indian Ocean Warming and Its Spatial Pattern in CMIP Models |
| title_full_unstemmed | Drivers of Future Indian Ocean Warming and Its Spatial Pattern in CMIP Models |
| title_short | Drivers of Future Indian Ocean Warming and Its Spatial Pattern in CMIP Models |
| title_sort | drivers of future indian ocean warming and its spatial pattern in cmip models |
| topic | Indian Ocean CMIP IOD like warming pattern Indian Ocean basin average warming air‐sea interaction interhemispheric gradient |
| url | https://doi.org/10.1029/2025EF006112 |
| work_keys_str_mv | AT sgopika driversoffutureindianoceanwarminganditsspatialpatternincmipmodels AT ksadhvi driversoffutureindianoceanwarminganditsspatialpatternincmipmodels AT jvialard driversoffutureindianoceanwarminganditsspatialpatternincmipmodels AT vdanielli driversoffutureindianoceanwarminganditsspatialpatternincmipmodels AT sneetu driversoffutureindianoceanwarminganditsspatialpatternincmipmodels AT mlengaigne driversoffutureindianoceanwarminganditsspatialpatternincmipmodels |