Causes for Atlantic Freshwater Content Variability in the GECCO3 Ocean Synthesis

Regional freshwater content (FWC) changes are studied over the period 1961–2018 using the GECCO3 ocean synthesis. In four dynamically distinct regions of the Atlantic, the study identifies causes for FWC variability with a focus on interannual and decadal time-scale changes. Results show that in eac...

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Bibliographic Details
Published in:Journal of Geophysical Research: Oceans
Main Authors: Liu, X., Köhl, A., Stammer, D.
Format: Article in Journal/Newspaper
Language:English
Published: AGU 2023
Subjects:
Online Access:https://publications.hereon.de/id/51118
https://publications.hzg.de/id/51118
https://doi.org/10.1029/2022JC018796
Description
Summary:Regional freshwater content (FWC) changes are studied over the period 1961–2018 using the GECCO3 ocean synthesis. In four dynamically distinct regions of the Atlantic, the study identifies causes for FWC variability with a focus on interannual and decadal time-scale changes. Results show that in each region, it is a combination of the surface freshwater flux and the net freshwater transport across the region\'s boundaries that act jointly in changing the respective FWC. Surface flux mainly contributes to the FWC variability on multi-decadal time scales. The impact of surface flux also increases toward the tropics. On shorter time scales, it is especially horizontal transport fluctuations, leading to FWC changes in mid and high latitudes. Going from north to the south, the transport across a single meridional boundary becomes less correlated with the FWC changes but the net transport across both boundaries plays an increasingly important role. Moreover, the subpolar box is mainly gyre driven, which differs from the other two, essentially overturning driven, North Atlantic boxes. In the tropical Atlantic, the shallow overturning cell and the deep overturning contribute about equal amounts to the freshwater variations.