scholarly journals Galápagos upwelling driven by localized wind–front interactions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexander Forryan ◽  
Alberto C. Naveira Garabato ◽  
Clément Vic ◽  
A. J. George Nurser ◽  
Alexander R. Hearn
Keyword(s):  
Ocean Circulation ◽  
Realistic Model ◽  
Surface Mixed Layer ◽  
Equatorial Pacific Ocean ◽  
World Heritage Sites ◽  
Theory Of Evolution ◽  
Heritage Sites ◽  
Galapagos Archipelago ◽  
Eastern Equatorial Pacific ◽  
Eastern Equatorial Pacific Ocean

AbstractThe Galápagos archipelago, rising from the eastern equatorial Pacific Ocean some 900 km off the South American mainland, hosts an iconic and globally significant biological hotspot. The islands are renowned for their unique wealth of endemic species, which inspired Charles Darwin’s theory of evolution and today underpins one of the largest UNESCO World Heritage Sites and Marine Reserves on Earth. The regional ecosystem is sustained by strongly seasonal oceanic upwelling events—upward surges of cool, nutrient-rich deep waters that fuel the growth of the phytoplankton upon which the entire ecosystem thrives. Yet despite its critical life-supporting role, the upwelling’s controlling factors remain undetermined. Here, we use a realistic model of the regional ocean circulation to show that the intensity of upwelling is governed by local northward winds, which generate vigorous submesoscale circulations at upper-ocean fronts to the west of the islands. These submesoscale flows drive upwelling of interior waters into the surface mixed layer. Our findings thus demonstrate that Galápagos upwelling is controlled by highly localized atmosphere–ocean interactions, and call for a focus on these processes in assessing and mitigating the regional ecosystem’s vulnerability to 21st-century climate change.

scholarly journals Protistan plankton communities in the Galapagos Archipelago respond to changes in deep water masses resulting from the 2015/16 El Nino

2021 ◽  
Author(s):  
Erika F Neave ◽  
Harvey Seim ◽  
Scott Gifford ◽  
Olivia Torano ◽  
Zackary I Johnson ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Deep Water ◽  
El Niño ◽  
El Nino ◽  
18S Rrna Gene ◽  
Rrna Gene ◽  
Equatorial Pacific Ocean ◽  
Equatorial Undercurrent ◽  
Galapagos Archipelago ◽  
Eastern Equatorial Pacific

The Galapagos Archipelago lies within the eastern equatorial Pacific Ocean at the convergence of major ocean currents that are subject to changes in circulation. The nutrient-rich Equatorial Undercurrent upwells from the west onto the Galapagos platform, stimulating primary production, but this source of deep water weakens during El Nino events. From measurements collected on repeat cruises, the 2015/16 El Nino was associated with declines in phytoplankton biomass at most sites throughout the archipelago and reduced utilization of nitrate, particularly in large-sized phytoplankton in the western region. Protistan assemblages were identified by sequencing the V4 region of the 18S rRNA gene. Dinoflagellates, chlorophytes, and diatoms dominated most sites. Shifts in dinoflagellate communities were most apparent between the years; parasitic dinoflagellates, Syndiniales, were highly detected during the El Nino (2015) while the dinoflagellate genus, Gyrodinium dominated many sites during the neutral period (2016). Variations in protistan communities were most strongly correlated with changes in subthermocline water density. These findings indicate that marine protistan communities in this region are regimented by deep water mass sources and thus could be profoundly affected by altered ocean circulation.

Middle Miocene to Pleistocene Planktonic Foraminiferal Biostratigraphy in the Eastern Equatorial Pacific Ocean

2013 ◽  
Vol 17 (1) ◽  
pp. 91-109 ◽  
Author(s):  
Hiroki Hayashi ◽  
Kyoko Idemitsu ◽  
Bridget S. Wade ◽  
Yuki Idehara ◽  
Katsunori Kimoto ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Middle Miocene ◽  
Equatorial Pacific ◽  
Equatorial Pacific Ocean ◽  
Eastern Equatorial Pacific ◽  
Eastern Equatorial Pacific Ocean ◽  
Foraminiferal Biostratigraphy

scholarly journals A New Heuristic Lagrangian Marine Boundary Layer Cloud Model

2004 ◽  
Vol 61 (24) ◽  
pp. 3002-3024 ◽  
Author(s):  
Sungsu Park ◽  
Conway B. Leovy ◽  
Margaret A. Rozendaal
Keyword(s):  
Boundary Layer ◽  
Marine Boundary Layer ◽  
Cloud Model ◽  
Specific Humidity ◽  
Explicit Calculation ◽  
Equatorial Pacific Ocean ◽  
Eastern Equatorial Pacific ◽  
Boundary Layer Cloud ◽  
Lifting Condensation Level ◽  
Eastern Equatorial Pacific Ocean

Abstract A new heuristic model of stratocumulus cloudiness in the inversion-capped marine boundary layer is developed and tested. The essential ingredient is a new method for predicting the statistical distribution of temperature and specific humidity at the inversion base under partially decoupled conditions along steady-state marine boundary layer (MBL) trajectories. MBL decoupling is parameterized as an increasing function of the height difference between the inversion base and lifting condensation level (LCL) of the mixed-layer air. Required inputs are sea surface temperature (SST), free air (above inversion) temperature and humidity, subsidence velocity, and mean boundary layer wind speed. Upstream boundary conditions must also be specified but have little influence at sufficient downstream distances (>2000 km). The model is applied to the cold advection regime of the northeastern subtropical Pacific and to both warm and cold advection regimes of the eastern equatorial Pacific Ocean. The model is conceptually simple and avoids explicit calculation of several important physical processes. Nevertheless, it is at least qualitatively successful in predicting both the climatological mean properties and climate anomaly variations of MBL stratocumulus in both regions. These results suggest that, regardless of other properties, successful MBL stratocumulus models will need to accurately predict inversion base height and the LCL and they will have to account for downstream memory effects.

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