Impacts of a weakened AMOC on precipitation over the Euro-Atlantic region in the EC-Earth3 climate model

Climate Dynamics, Год журнала: 2023, Номер 61(7-8), С. 3397 - 3416

Опубликована: Март 16, 2023

Abstract Given paleoclimatic evidence that the Atlantic Meridional Overturning Circulation (AMOC) may affect global climate system, we conduct model experiments with EC-Earth3, a state-of-the-art GCM, to specifically investigate, for first time, mechanisms of precipitation change over Euro-Atlantic sector induced by weakened AMOC. We artificially weaken strength AMOC in through release freshwater anomaly into Northern Hemisphere high latitude ocean, thereby obtaining ~ 57% weaker respect its preindustrial 60 years. Similar prior studies, find decreases response However, also frequency wet days increases some regions. By computing atmospheric moisture budget, intensified but drier storms cause less land. Nevertheless, changes jet stream tend enhance northwestern Europe. further investigate association anomalies large-scale circulations weather regimes clustering geopotential height daily anomalies. an increase positive phase North Oscillation (NAO+), which is associated occurrence northern Europe and conditions southern Since reduction within inter-model range projected declines end twenty-first century, our results have implications understanding role future hydrological changes.

Язык: Английский

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The strengthened impact of water availability at interannual and decadal time scales on vegetation GPP

Global Change Biology, Год журнала: 2024, Номер 30(1)

Опубликована: Янв. 1, 2024

Water availability (WA) is a key factor influencing the carbon cycle of terrestrial ecosystems under climate warming, but its effects on gross primary production (E

Язык: Английский

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High-latitude precipitation as a driver of multicentennial variability of the AMOC in a climate model of intermediate complexity

Climate Dynamics, Год журнала: 2022, Номер 61(3-4), С. 1519 - 1534

Опубликована: Дек. 28, 2022

Abstract Centennial-scale variability of the Atlantic Meridional Overturning Circulation (AMOC) in absence external forcing has been identified several climate models, but proposed mechanisms differ considerably. Therefore, better understanding processes governing AMOC at these timescales is needed. Here, we analyze numerical simulations with PlaSim-LSG, an Earth System Model Intermediate Complexity (EMIC), which exhibits strong multicentennial oscillations strength under constant pre-industrial boundary conditions. We identify a novel mechanism are driven by salinity anomalies from Arctic Ocean, can be attributed to changes high-latitude precipitation. further corroborate our findings conducting set millennial-length sensitivity experiments, and interpret formulating three-box model qualitatively reproduces regular AMOC. While PlaSim-LSG lacks complexity compared state-of-the-art results reveal that precipitation minus evaporation (P–E) change physically plausible driver centennial-scale variability. discuss how this might most relevant states warmer than present-day, raising questions about state-dependence

Язык: Английский

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A multicentennial mode of North Atlantic climate variability throughout the Last Glacial Maximum

Science Advances, Год журнала: 2023, Номер 9(44)

Опубликована: Ноя. 1, 2023

Paleoclimate proxy records from the North Atlantic region reveal substantially greater multicentennial temperature variability during Last Glacial Maximum (LGM) compared to current interglacial. As there was no obvious change in external forcing, causes for increased remain unknown. Exploiting LGM simulations with a comprehensive coupled climate model along high-resolution records, we introduce an oscillatory mode of variability, which is associated moderate variations meridional overturning circulation and depends on large-scale salinity distribution. This self-sustained amplified by sea-ice feedbacks induces maximum surface subpolar region. Characterized distinct climatic imprint different dynamics, oscillation has be distinguished Dansgaard-Oeschger emerges only under full forcing. The potential modes emerge or disappear response changing forcing may have implications future change.

Язык: Английский

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Contrasting internally and externally generated Atlantic Multidecadal Variability and the role for AMOC in CMIP6 historical simulations

Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences, Год журнала: 2023, Номер 381(2262)

Опубликована: Окт. 22, 2023

Atlantic multidecadal variability (AMV) has long been thought to be an expression of low-frequency in the Meridional Overturning Circulation (AMOC). However, alternative hypotheses have forwarded, including that AMV is primarily externally forced. Here, we review current state play by assessing historical simulations made for sixth coupled model intercomparison project (CMIP6). Overall, importance external forcing sensitive type index used, due globally coherent forced signals models. There are also significant contrasts between processes drive internally and AMV, but these can isolated exploring multivariate AMV. Specifically, internal CMIP6 models consistent with important role ocean circulation AMOC largely a surface-flux mechanism little ocean. fingerprint similar observed, appears inconsistent observations. Therefore, climate still suggest key dynamics, specifically AMOC, observed Nevertheless, remain deficient number areas, stronger dynamical changes cannot ruled out. This article part discussion meeting issue 'Atlantic overturning: new observations challenges'.

Язык: Английский

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Large diversity in AMOC internal variability across NEMO-based climate models

Climate Dynamics, Год журнала: 2024, Номер 62(5), С. 3355 - 3374

Опубликована: Янв. 31, 2024

Abstract We characterise, and explore the drivers of, differences in internal variability of atlantic meridional overturning circulation (AMOC) across five NEMO-based CMIP6 class climate models. While AMOC is dominated by its lower dense limb all models, there large diversity timescale, multidecadal variability, latitudinal coherence In particular, UK models have much weaker coherence. The model associated with salinity-governed surface density variations which drive high-density water mass transformation (WMT) Greenland–Iceland–Norwegian Seas (GIN) Arctic. Specifically, GIN WMT shows has a major impact on non-UK contrast, smaller limited latitude via Denmark strait overflow transport. This leads to latitudinally less coherent limb. Such between are related mean states densification processes Arctic Seas. Consequently, we recommend further in-depth studies better understand constrain driving salinity changes for more reliable representation

Язык: Английский

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Key drivers of large scale changes in North Atlantic atmospheric and oceanic circulations and their predictability

Climate Dynamics, Год журнала: 2025, Номер 63(2)

Опубликована: Фев. 1, 2025

Significant changes have occurred during the last few decades across North Atlantic climate system, including in atmosphere, ocean, and cryosphere. These large-scale play a vital role shaping regional extreme weather events UK Western Europe. This review synthesizes characteristics of observed atmospheric oceanic circulations past decades, identifies drivers physical processes responsible for these changes, outlines projected due to anthropogenic warming, discusses predictability circulations. On multi-decadal time scales, internal variability, forcings (especially greenhouse gases), natural (such as solar variability volcanic eruptions) are identified key contributors However, there remain many uncertainties regarding detailed various influences, some cases their relative importance. We therefore conclude that better understanding drivers, more accurate quantification roles, crucial reliable decadal predictions projections The online version contains supplementary material available at 10.1007/s00382-025-07591-1.

Язык: Английский

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AMOC Variability in Climate Models and Its Dependence on the Mean State

Geophysical Research Letters, Год журнала: 2025, Номер 52(3)

Опубликована: Фев. 9, 2025

Abstract Understanding internal variability of the climate system is critical when isolating and anthropogenically forced signals. Here, we investigate modes Atlantic Meridional Overturning Circulation ( AMOC ) using perturbation experiments with Institut Pierre‐Simon Laplace's (IPSL) coupled model compare them to Coupled Model Intercomparison Project Phase 6 (CMIP6) pre‐industrial control simulations. We identify two characteristic variability—decadal‐to‐multidecadal DMD var centennial CEN ). The former driven largely by temperature anomalies in subpolar North Atlantic, while latter salinity western Atlantic. amplitude each mode scales linearly mean strength IPSL experiments. correlates well across CMIP6 models, does not. These findings suggest that depends robustly on state, may be model‐dependent.

Язык: Английский

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Suppressed AMOC multidecadal variability by freshwater flux change in the Community Earth System Model version 1.0

Global and Planetary Change, Год журнала: 2025, Номер unknown, С. 104794 - 104794

Опубликована: Март 1, 2025

Язык: Английский

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Constraining CMIP6 simulations for Atlantic Water in the Arctic using an AMOC-SST index

Frontiers in Climate, Год журнала: 2025, Номер 7

Опубликована: Апрель 30, 2025

Atlantic Water plays a key role in future changes the Arctic Ocean. It contributes to Atlantification by transporting salt and heat within Ocean basins. Many studies also attribute amplified warming of an increase poleward ocean transport currents or increasing strength currents. Global models are needed reliably predict consistent trends transport, as large-scale processes at play. However, these too coarse resolve address complex interplay between dynamics bathymetry region. Here, we propose construct sub-ensemble simulations based on 235 historical from 12 CMIP6 that best represent downstream drivers warming. We select model ensemble members showing closest agreement with observed surface temperature variability over 1960–1990 subpolar gyre (SPG). More specifically, use recent index links SPG Overturning Meridional Circulation (AMOC): AMOC-SST index. The subsampled shows better correlation last 35 years period (1980–2014). displays reduced error for core depth Eurasian when compared reanalysis observations. Overall, index-based selection leads systematic improvement representation layer region, suggesting clear connection extension, possibly AMOC.

Язык: Английский

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