Eastern Boundary Upwelling Systems response to different atmospheric forcing in a global eddy-permitting ocean model

Bonino, Giulia; Masina, Simona; Iovino, Doroteaciro; Storto, Andrea; Tsujino, Hiroyuki

doi:10.1016/j.jmarsys.2019.05.004

Cited by 10 publications

(12 citation statements)

References 55 publications

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“…Our climatological run was forced with monthly mean winds derived from ERA-Interim (Dee et al, 2011), which, at the time of testing, provided an overall better performance of the model compared to other QuickSCAT products (Risien and Chelton, 2008). Despite the well known biases of Era-Interim product at coast (Bonino et al, 2019b;Taboada et al, 2019), our upwelling estimations are in agreement with Messié et al (2009) estimations, which compute vertical transports from…”

Section: Model Limitationssupporting

confidence: 52%

Drivers and impact of the seasonal variability of the organic carbon offshore transport in the Canary Upwelling System

Bonino¹,

Lovecchio²,

Gruber³

et al. 2020

Preprint

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Abstract. The Canary Upwelling System (CanUS) is a productive coastal region characterized by strong seasonality and an intense offshore transport of organic carbon (Corg) to the adjacent oligotrophic offshore waters. There, the respiration of this Corg substantially modifies net community production (NCP). While this transport and the resulting coupling of the biogeochemistry between the coastal and open ocean has been well studied in the annual mean, the temporal variability, and especially its seasonality has not yet been investigated. Here, we fill this gap, and determine the seasonal variability of the offshore transport of Corg, its mesoscale component, latitudinal differences, and the underlying physical and biological drivers. To this end, we employ the Regional Ocean Modeling System (ROMS) coupled to a nutrient, phytoplankton, zooplankton, and detritus (NPZD) ecosystem model. Our results reveal the importance of the mesoscale fluxes and of the upwelling processes (coastal upwelling and Ekman pumping) in modulating the seasonal variation of the offshore Corg transport. We find that the region surrounding Cape Blanc (21° N) hosts the most intense Corg offshore flux in every season, linked to the persistent, and far reaching Cape Blanc filament. Coastal upwelling filaments dominate the seasonality of the total offshore flux up to 100 km from the coast, contributing in every season season at least 80 % to the total flux. The seasonality of the upwelling modulates the offshore Corg seasonality hundreds of km from the CanUS coast via lateral redistribution of nearshore production. North of 24.5° N, the sharp summer-fall peak of coastal upwelling results in an export of more than 30 % of the coastal Corg at the 100 km offshore due to a combination of intensified nearshore production and offshore fluxes. To the south, the less pronounced upwelling seasonality regulates an overall larger, but farther-reaching and less seasonally varying lateral flux, which exports between 60 and 90 % of the coastal production more than 100 km offshore. Overall, we show that the temporal variability of nearshore processes impacts the variability of Corg and NCP hundreds of km offshore from the CanUS coast via the offshore transport of the nearshore production.

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Section: Model Limitationssupporting

confidence: 52%

Drivers and impact of the seasonal variability of the organic carbon offshore transport in the Canary Upwelling System

Bonino¹,

Lovecchio²,

Gruber³

et al. 2020

Preprint

Self Cite

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“…The authors further claimed that this atmospheric resolution is required for a better representation of the simulated wind stress curl near the African coast. In line with this, the model study of [149] highlighted that near-shore wind affects the representation of near-surface eastern boundary currents and this has a concomitant impact on the SST. Regarding the vertical resolution of the models, in ref.…”

Section: Modeling the Climate Of The Tamentioning

confidence: 56%

Tropical Atlantic Variability: Observations and Modeling

2019

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We review the state-of-the-art knowledge of Tropical Atlantic Variability (TAV). A well-developed observing system and sustained effort of the climate modeling community have improved our understanding of TAV. It is dominated by the seasonal cycle, for which some mechanisms have been identified. The interannual TAV presents a marked seasonality with three dominant modes: (i) the Atlantic Zonal Mode (AZM), (ii) the Atlantic Meridional Mode (AMM) and (iii) the variability in the Angola–Benguela Front (ABF). At longer time scales, the AMM is active and low-frequency variations in the strength, periodicity, and spatial structure of the AZM are observed. Also, changes in the mean position of the ABF occur. Climate models still show systematic biases in the simulated TAV. Their causes are model-dependent and relate to drawbacks in the physics of the models and to insufficient resolution of their atmospheric and oceanic components. The identified causes for the biases can have local or remote origin, involving the global ocean and atmospheric circulation. Although there is not a clear consensus regarding the role of model resolution in the representation of the TAV, eddy-resolving ocean models combined with atmospheric models with enhanced horizontal and vertical resolutions simulate smaller biases.

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“…This technique allows for the correction of coastal wind patterns off EBUS, due to the accuracy of QuikSCAT 53,54 . In JRA55, although significantly improving on ERAInterim 55 , the representation of wind drop off is still an open issue that can effect Ekman pumping, coastal upwelling 9 and alongshore transport 56 . In addition, the resolution of the Japanese reanalysis (~55 km) is still too coarse to resolve upwelling dynamics, which are typically confined to within 30 km from the coast.…”

Section: Methodsmentioning

confidence: 99%

Interannual to decadal variability within and across the major Eastern Boundary Upwelling Systems

Bonino

Lorenzo

Masina

et al. 2019

Sci Rep

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Climate variability and climate change in Eastern Boundary Upwelling Systems (EBUS) affect global marine ecosystems services. We use passive tracers in a global ocean model hindcast at eddy-permitting resolution to diagnose EBUS low-frequency variability over 1958–2015 period. The results highlight the uniqueness of each EBUS in terms of drivers and climate variability. The wind forcing and the thermocline depth, which are potentially competitive or complementary upwelling drivers under climate change, control EBUS low-frequency variability with different contributions. Moreover, Atlantic and Pacific upwelling systems are independent. In the Pacific, the only coherent variability between California and Humboldt Systems is associated with El Niño Southern Oscillation. The remaining low-frequency variance is partially explained by the North and South Pacific expressions of the Meridional Modes. In the Atlantic, coherent variability between Canary and Benguela Systems is associated with upwelling trends, which are not dynamically linked and represent different processes. In the Canary, a negative upwelling trend is connected to the Atlantic Multi-decadal Oscillation, while in the Benguela, a positive upwelling trend is forced by a global sea level pressure trend, which is consistent with the climate response to anthropogenic forcing. The residual variability is forced by localized offshore high sea level pressure variability.

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Eastern Boundary Upwelling Systems response to different atmospheric forcing in a global eddy-permitting ocean model

Cited by 10 publications

References 55 publications

Drivers and impact of the seasonal variability of the organic carbon offshore transport in the Canary Upwelling System

Drivers and impact of the seasonal variability of the organic carbon offshore transport in the Canary Upwelling System

Tropical Atlantic Variability: Observations and Modeling

Interannual to decadal variability within and across the major Eastern Boundary Upwelling Systems

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