Decoupled freshwater transport and meridional overturning in the South Atlantic
Freshwater transports (F_ov) by the Atlantic Meridional Overturning Circulation (AMOC) are sensitive to salinity distributions and may determine AMOC stability. However, climate models show large salinity biases, distorting the relation between F_ov and the AMOC. Using free-running models and ocean...
| Published in: | Geophysical Research Letters |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
American Geophysical Union
2019
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| Subjects: | |
| Online Access: | https://centaur.reading.ac.uk/82184/ https://centaur.reading.ac.uk/82184/8/Mignac_et_al-2019-Geophysical_Research_Letters.pdf https://centaur.reading.ac.uk/82184/1/Mignac_etal_2019_accepted.pdf |
| Summary: | Freshwater transports (F_ov) by the Atlantic Meridional Overturning Circulation (AMOC) are sensitive to salinity distributions and may determine AMOC stability. However, climate models show large salinity biases, distorting the relation between F_ov and the AMOC. Using free-running models and ocean reanalyses with realistic salinities but quite different AMOCs, we show that the fresh Antarctic Intermediate Water (AAIW) layer eliminates salinity differences across the AMOC branches at ~1200 m, ∆S_1200m, which decouples F_ov from the AMOC south of ~10˚N. As AAIW disappears north of ~10˚N, a large ∆S_1200m allows the AMOC to drive substantial southward F_ov in the North Atlantic. In the South Atlantic the 0-300 m zonal salinity contrasts control the gyre freshwater transports F_gyre, which also determine the total freshwater transports. This decoupling makes the southern F_ov unlikely to play any role in AMOC stability, leaving indirect F_gyre feedbacks or F_ov in the north, as more relevant factors. |
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