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(a) Amplitude (in centimeters per second) and phase (in hours) of the semimajor axis of the diurnal tidal ellipses derived from the fit to the 25-hour transect repetitions of 5 and 6 December. Flows are represented by open areas >10 cm/s. (b) Positive phase represented by open areas and negative phase represented by shaded areas. View is northward.
Source publication
1] Shipborne observations of hydrographic and flow velocity profiles were combined with wind velocity measurements to describe the characteristics of the wind-induced flow in an equatorward facing bay of central Chile in South America. The measurements, which were taken from two transects and one anchor station, were made during late austral spring...
Contexts in source publication
Context 1
... The distributions of the amplitude and phase ( Figure 8) of the diurnal currents revealed the locations in Boca Grande that responded best to the sea breeze forcing. These distributions showed maximum diurnal variability at a sur- face layer that tilted upward toward the east (Figure 8a). ...
Context 2
... The distributions of the amplitude and phase ( Figure 8) of the diurnal currents revealed the locations in Boca Grande that responded best to the sea breeze forcing. These distributions showed maximum diurnal variability at a sur- face layer that tilted upward toward the east (Figure 8a). They also exhibited large variability below the surface and near the ends of the transect. ...
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... also exhibited large variability below the surface and near the ends of the transect. The diurnal phase distributions showed a subsurface layer with a 12-hour lag relative to the surface layer, which indicated flows in opposite directions (Figure 8b). The combination of the diurnal amplitude and phase distributions illustrated a surface layer, approximately delimited by the pycnocline (Figure 4), moving in the same direction as the sea breeze and a subsurface layer moving simultaneously in the opposite direction. ...
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... regions of greatest diurnal variability were likely related to local wind forcing. The band of minimum diurnal variability that almost crossed from one side to the other of Boca Grande (Figure 8a) represented the transitions in the vertical plane of the oppositely directed flows. The other region of low variability in the deepest part of the section was likely connected to the relatively steady, southward flowing upw- elled water that was forced remotely. ...
Context 5
... r, " r, g, z, and h are the water density as a function of depth, the depth-averaged water density, the acceleration due to gravity, the vertical coordinate (positive upward), and the water column depth, respectively. The values of j from the eastern station at Boca Grande (Figure 8a) for 5 and 6 December indicate the greatest stratification (greatest values of j) late in the day, around 2000 local time, and weakest stratification early in the day, around 0600 (circles and plus signs in Figure 12a). These stratification patterns are very similar, qualitatively, to those observed in Boca Chica (asterisks in Figure 12a), although the values are markedly smaller. ...
Citations
... Investigations addressing the upwelling impact on the gravitational circulation, or the upwelling effect upon the estuarine hydrography (Monteiro and Largier 1999;Valle-Levinson et al. 2003), were carried out on mid-latitudes of the eastern ocean margins, where upwelling processes are notoriously vigorous and promote sharper thermal (density) gradients between warmer estuarine and colder shelf waters (Monteiro and Largier 1999). Although coastal upwelling has also been documented in tropical regions and on western ocean margins (Berkelmans et al. 2010;Rueda-Roa and Muller-Karger 2013;Thévenin et al. 2019), the investigation of its impact on the estuarine circulation is probably restricted to the study by Sun et al. (2018) on the upwellingforced gravitational circulation in sub-tropical Jervis Bay, on the eastern Australia coast. ...
This study examines the effects of coastal upwelling on the longitudinal water density gradient within the estuary of Baía de Todos os Santos (BTS), its effect on the gravitational circulation at the estuary entrance, and the reverse effect of gravitational circulation on the coastal upwelling. This investigation was based on a 1-year dataset of observed water temperature, mean velocities, and river discharge, as well as 2 years of numerical simulation of the estuarine flow. The results show that the upwelling regulates the thermohaline field in front of the BTS, decreasing water temperature (up to 3 °C), and increasing density (up to 0.3 kg/m3), and have sufficient intensity to more than double the speed, or even establish, the gravitational circulation. It was frequently observed that the water temperature falls after an increase in the subtidal flow shear, suggesting that the estuarine gravitational circulation acts as a facilitator to the upwelling process. Numerical simulations indicate that the coastal upwelling events are also capable of reestablishing the gravitational circulation at times with weak longitudinal density gradient, a scenario that tends to become more frequent and intense in the near future due to the ongoing climate changes.
... On the other hand, the primary hydrodynamical forcing in the GA (in which the Biobio discharges are higher compared with other local small tributaries) are (i) surface winds, which have a well-defined semiannual signal (Saavedra, 1980;Parada et al., 2001) and a synoptic signal (Wong et al., 2021;Mardones et al., 2022); (ii) buoyancy fluxes, associated with local atmospheric air-sea heat exchanges (Mardones et al., 2022), (iii) freshwater discharge (Valle-Levinson et al., 2003;Saldías et al., 2012) coming from the Biobio and others rivers; (iv) the upwelling of dense subsurface waters forced by seasonal variable winds along the coast and, (v) Canyon upwelling of cold, high-nutrient, low oxygen waters at the head of the Biobio Submarine Canyon (~36°.8°S, Fig.1b). ...
... As other coastal embayments in the PUS (e.g. Sechura bay, 5.5 • S; Flores et al., 2019; Independencia bay, 14.2 • S; Taylor et al., 2008) and along the Chilean coast (Tongo bay, 30 • S; Lagos et al., 2016; Arauco bay, 37 • S; Valle-Levinson et al., 2003), Paracas bay undergoes a strong anthropogenic pressure: traditional scallop (Argopecten purpuratus) aquaculture takes place in the bay, and artisanal and industrial landings of anchovy in Pisco harbour north of the bay amount to ~10% of the total Peruvian landings. Fish meal factories (transforming anchovy into oil and flour) in the Pisco area discharge huge amounts of fish waste through a submarine emissary (at 50 m depth) north of Paracas bay, possibly playing a role in the triggering of extreme events such as HABs (Cabello et al., 2002;Cuellar-Martinez et al., 2021). ...
The circulation and stratification in the shallow semi-enclosed bay of Paracas located downstream of the main upwelling cell off the Peruvian coast were studied during the summer season using a regional circulation model and in situ observations. A downscaling strategy based on a series of three embedded grids, from 10 km to 500 m resolution in the bay allows to take into account the influence of remote perturbations on the bay dynamics. Debiased surface winds from a high-resolution regional atmospheric model were used to force the model. The shortwave absorption depth was parameterized using satellite measurements of surface chlorophyll.
Sensitivity experiments to the model forcing and parameterizations were performed to investigate the impact of the wind diurnal variability, tidal forcing, freshwater discharge from a nearby river and shortwave absorption depth on the bay stratification. Results show that: debiasing the wind intensity reduced the model cold bias in the bay and increase the stratification; a shallow shortwave absorption depth induced a cooling of the subsurface water, increasing the stratification; freshwater discharge from the Pisco river north of the bay increased slightly the stratification in the bay during days of weak wind. The high sensitivity of the bay stratification to the atmospheric forcing calls for the need to use more realistic wind forcing products.
The circulation in the bay under strong (>5.5 m s-1) and weak (<3 m s-1) winds was also examined. The summer circulation during strong upwelling-favorable wind conditions was characterized by northward surface currents transporting the bay surface waters outward and subsurface currents transporting cold deeper waters
into the bay along its western shore. During weak wind conditions, the current is outward in the bottom layer and a surface southward current related to the poleward undercurrent flowing over the continental slope and shelf transported warm waters into the bay, generating a cyclonic circulation in the bay.
... Moreover, Aguirre et al. (2021) recently defined this zone as the region with the highest probability (∼70% in spring-summer) of having a CLLJ event together with a migratory anticyclone approaching the coast farther south (Aguirre et al., 2021). Adjacent to PL is the Gulf of Arauco (GA) (Figure 1), one of the largest and most productive equatorward-facing bays in all of South America (Valle-Levinson et al., 2003;Yannicelli et al., 2006). ...
... We suggest that the relative absence of zonal advection is due to the topographic characteristics of the GA. Specifically, the presence of SMI and the shallow depth of BC (<25 m) limit the water exchange between GA and the continental shelf to the west (Valle-Levinson et al., 2003). Then, the only options left to contribute to the observed warming within the GA could be the surface meridional heat advection (from the north) or the ocean-atmosphere heat exchange (radiative or convective). ...
Some semienclosed bays in the eastern boundary upwelling systems worldwide display a strong surface temperature gradient between cold water upwelled outside and warmer water inside these bays. This anomalous coastal temperature pattern is known as upwelling shadow (US). Research on this topic has mainly focused on identifying spatiotemporal patterns of US events, but the influence of the atmospheric synoptic variability on the temporal evolution of US events remains less well documented. This study uses observational, satellite‐derived, and reanalysis data to propose a mechanism that relates synoptic‐scale atmospheric phenomena with the development of US events in the Gulf of Arauco (GA), a highly productive and the largest semienclosed bay in central Chile (around 37°S). The mechanism associates the passage of migratory anticyclones over the study area with two key processes. The first process is the formation of a coastal low‐level wind jet, which intensifies the upwelling of cold subsurface waters outside the GA. We strongly suggest that the second one is the development of a coastal low pressure, which usually implies clear skies (increasing the solar radiation input) and weak downwelling favorable winds along the coast, factors that could largely explain the observed surface warming inside this embayment during these events. The presence of cold water upwelled offshore and the enhanced surface warming inside the GA, possibly also modulated by a weakened circulation, results in a strong thermal gradient with average temperature differences of more than 3°C, generating the US.
... The vertical distribution is relative to nektonic and planktonic organisms that move in water columns, reaching the shallowest areas (Lauretta and Penchaszadeh, 2017;Bernal et al., 2019). Valle-Levinson et al. (2003; Figure 5J), have suggested two mechanisms that may cause the high primary productivity of the system of current and hydrographic variables in an equatorward facing bay adjacent to a coastal upwelling center. According to them, it is related to a persistent flow into the gulf through the deepest part nearby Biobio canyon and would be described with the diurnal variability in heat from ocean-atmosphere interactions and horizontal momentum from wind-driven stress, as mentioned previously. ...
Submarine canyons have a relevant role in marine ecosystems. They are responsible for oceanographic conditions such as variability of temperature and salinity, sediment transport, nutrients, and even pollutants amongst marine areas. Submarine canyon studies have been growing and reaching prominence due to their importance in the Blue Economy. Initiatives to promote sustainable development for the ocean have been discussed in the Ocean Decade. Although canyons studies are increasing, how can we integrate these with the Ocean Decade outcomes? Thus, we aim to demonstrate an overview of the advances of submarine canyons studies and their link to the Ocean Decade for South America. We analyzed 160 studies divided into spatiotemporal analysis and study approaches according to the Ocean Decade outcomes. We discuss these articles, building a timeline and argumentative topics considering the advances, and discuss gaps to predict the future of submarine canyons studies in the Ocean Decade and Blue Economy context.
... Moreover, Aguirre et al. (2021) recently defined this zone as the region with the highest probability (∼70% in spring-summer) of having a CLLJ event together with a migratory anticyclone approaching the coast farther south (Aguirre et al., 2021). Adjacent to PL is the Gulf of Arauco (GA) (Figure 1), one of the largest and most productive equatorward-facing bays in all of South America (Valle-Levinson et al., 2003;Yannicelli et al., 2006). ...
... We suggest that the relative absence of zonal advection is due to the topographic characteristics of the GA. Specifically, the presence of SMI and the shallow depth of BC (<25 m) limit the water exchange between GA and the continental shelf to the west (Valle-Levinson et al., 2003). Then, the only options left to contribute to the observed warming within the GA could be the surface meridional heat advection (from the north) or the ocean-atmosphere heat exchange (radiative or convective). ...
... Bays influenced by coastal upwelling have been studied in Chile, where they seem to respond mainly to the local winds (Valle-Levinson et al., 2003. These bays are similar to the Rias Baixas, however their main axes are oriented nearly parallel to the Chilean coast while the Rias Baixas are oriented obliquely to the Iberian Atlantic coast. ...
Estuarine exchange flow plays an important role in the biogeochemical properties exchange between the coastal ocean and the estuaries. Circulation patterns inside the Rias Baixas (NW Iberian Peninsula) have been widely studied, while the Ría de Pontevedra has received less attention. A high-resolution ROMS-AGRIF system configuration with three online two-way nesting domains was used and validated to enhance the knowledge about the circulation patterns of this Ría. Two representative estuarine circulation patterns were studied: a coastal upwelling event and a downwelling event associated with a maximum river runoff of 84 m³/s. An analysis using Empirical Orthogonal Functions (EOF) was applied to the horizontal subtidal velocity fields at the surface layer and at 20 m depth and to the subtidal normal velocity across vertical cross-sections. Upwelling events are characterized by a reinforcement of the positive estuarine circulation, in which the surface waters outflow and deep waters inflow at the main sill of the Ría, whilst full water column inflow (outflow) is observed at the northern (southern) openings. Conversely, downwelling events induce an opposite behavior, consisting of a negative estuarine circulation with the surface (deep) inflow (outflow) at the main sill of the Ría and outflow (inflow) at the northern (southern) openings. Evidences of a front splitting two vertical clockwise circulation cells were found. These cells are associated with the ocean water subduction that enters through the surface layer under downwelling favorable winds and this surface inflow opposes to the direction of the inner estuarine circulation. The EOF study confirms that shelf wind forcing has an important contribution to the variability of the velocity field, inducing positive or negative estuarine like circulation. The temporal principal components (PC) of EOF analysis present correlations of 0.92 between the meridional wind component and the first mode, and 0.77 between the zonal wind component and the second mode. Third EOF mode represents the circulation during transitional winds when some vorticity structures are visible. The realistic high-resolution simulation of the physical conditions at the Ría de Pontevedra provides new insights into the ocean-estuarine water exchanges and allow the visualization of recirculation processes and characteristic structures that have consequences in the marine ecosystem and in their productivity.
... BC: Biobio Canyon; BR: Biobio River; SMI: Santa Maria Island; BG: Boca Grande; PP: Punta Puchoco; BC: Boca Chica; PL: Punta Lavapie. ADCP, Valle-Levinson et al. (2003), described residual flows at Boca Grande and Boca Chica during late spring 2000. With northward wind conditions (upwelling-favorable), they found net downwind flow over the shallow areas on the east side of Boca Grande. ...
... South of PL, the orientation of the coastline is toward 350° (relative to the geographical North). North of PL, the coastline is oriented toward 20°, with respect to the geographical North (Valle- Levinson et al., 2003). (c) South of GA, the western border of the Nahuelbuta Mountain is located. ...
The upwelling shadow in the Gulf of Arauco (GA) is studied using 15 years of daily satellite images of Sea Surface Temperature (SST) from Geostationary Operational Environmental Satellites (GOES), as well as heat flux and wind data from the ERA5 reanalysis product. An Upwelling Shadow Index (USI) is developed based on the SST differences between the GA and the region off Punta Lavapie (PL) farther offshore, characterized by active upwelling. USI values greater than 0.91°C and SST differences less than 1.1°C, correspond to an upwelling shadow event. These cases occurred 10.29% of the time and were more frequent in spring/summer during events of upwelling‐favorable winds with strong cyclonic wind stress curl, interspersed with wind relaxations. Multiple correlations between USI and wind stress curl and solar radiation showed an r² = 40%–80% for some summer months. Most events persisted for only 1 day (53%), whereas 34% of upwelling shadow events lasted between 2 and 4 days and 9% of events were longer than 4 days. Water residence times as long as 15 days were observed in the GA during upwelling shadow events. During southerly wind relaxation (less than 2 days), cold surface waters flowing north from PL curved onshore and entered the GA from the north, weakening the thermal gradient between PL and GA and the upwelling shadow. Long periods of wind relaxation (at least 1 week) resulted in the dissipation of the thermal gradient due to the warming of offshore waters.
... BC: Biobio Canyon; BR: Biobio River; SMI: Santa Maria Island; BG: Boca Grande; PP: Punta Puchoco; BC: Boca Chica; PL: Punta Lavapie. ADCP, Valle-Levinson et al. (2003), described residual flows at Boca Grande and Boca Chica during late spring 2000. With northward wind conditions (upwelling-favorable), they found net downwind flow over the shallow areas on the east side of Boca Grande. ...
... South of PL, the orientation of the coastline is toward 350° (relative to the geographical North). North of PL, the coastline is oriented toward 20°, with respect to the geographical North (Valle- Levinson et al., 2003). (c) South of GA, the western border of the Nahuelbuta Mountain is located. ...
The upwelling shadow in the Gulf of Arauco (GA) is studied using 15 years of daily satellite images of Sea Surface Temperature (SST) from Geostationary Operational Environmental Satellites (GOES), as well as heat flux and wind data from the ERA5 reanalysis product. An Upwelling Shadow Index (USI) is developed based on the SST differences between the GA and the region off Punta Lavapie (PL) farther offshore, characterized by active upwelling. USI values greater than 0.91°C and SST differences less than 1.1°C, correspond to an upwelling shadow event. These cases occurred 10.29% of the time and were more frequent in spring/summer during events of upwelling-favorable winds with strong cyclonic wind stress curl, interspersed with wind relaxations. Multiple correlations between USI and wind stress curl and solar radiation showed and r2 = 40%-80% for some summer months. Most events persisted for only 1 day (53%), whereas 34% of upwelling shadow events lasted between 2 and 4 days and 9% of events were longer than 4 days. Water residence times as long as 15 days were observed in the GA during upwelling shadow events. During southerly wind relaxation (less than 2 days), cold surface waters flowing north from PL curved onshore and entered the GA from the north, weakening the thermal gradient between PL and GA and the upwelling shadow. Long periods of wind relaxation (at least 1 week) resulted in the dissipation of the thermal gradient due to the warming of offshore waters.
... La línea de costa en esta zona tiene una orientación norte-sur y su topografía es compleja, compuesta por bahías, golfos y puntas que intensifica el desarrollo de sombras de surgencia (Graham, 1993;Valle-Levinson 2003), filamentos, meandros y remolinos (Correa- Ramírez et al., 2007;Letelier et al., 2009). En sectores costeros que se encuentran a sotavento de centros de surgencia, como por ejemplo el golfo de Arauco (37°10'S), se conforma una estructura hidrográfica que ha sido denominada "sombra de surgencia" (Graham, 1993;Valle-Levinson, 2003), donde la productividad biológica presenta valores elevados en relación a zonas más expuestas. ...
... La línea de costa en esta zona tiene una orientación norte-sur y su topografía es compleja, compuesta por bahías, golfos y puntas que intensifica el desarrollo de sombras de surgencia (Graham, 1993;Valle-Levinson 2003), filamentos, meandros y remolinos (Correa- Ramírez et al., 2007;Letelier et al., 2009). En sectores costeros que se encuentran a sotavento de centros de surgencia, como por ejemplo el golfo de Arauco (37°10'S), se conforma una estructura hidrográfica que ha sido denominada "sombra de surgencia" (Graham, 1993;Valle-Levinson, 2003), donde la productividad biológica presenta valores elevados en relación a zonas más expuestas. Además, en los centros de surgencia, frente a punta Lavapie (37°9'S), la corriente que viene desde el sur se separa del borde costero formando un jet costero con dirección hacia el noroeste (Renault et al., 2009;Aguirre et al., 2012). ...
El objetivo general del estudio fue evaluar el stock desovante de anchoveta (Engraulis ringens) y sardina común (Strangomera bentincki) durante el período de máxima actividad reproductiva, en el área comprendida entre las regiones de Valparaíso y de Los Lagos, al mismo tiempo evaluar las condiciones oceanográficas imperantes durante este proceso. Para ello, se aplicó el Método de la Producción Diaria de Huevos (MPDH) en la zona centro sur de Chile (33 S – 41 30’S), que consistío en la realización de un crucero de huevos en tres estratos geográficos: a) Sector norte, sur de Valparaíso – norte de Constitución (33ºS – 34ºS), b) Sector centro, entre Constitución y Golfo de Arauco (34º30’S – 37º10’S) y c) Sector sur, entre el sur de Lebu – sur de punta Galera (37º30’S – 41º20’S). Además, en paralelo se realizó un crucero de pesca orientado a la extracción de hembras maduras en los sectores centro y sur, antes mencionados.
