scholarly journals On the Impact of the Caribbean Counter Current in the Guajira Upwelling System

2021 ◽  
Vol 8 ◽  
Author(s):  
Alejandro Orfila ◽  
Claudia P. Urbano-Latorre ◽  
Juan M. Sayol ◽  
Stephanie Gonzalez-Montes ◽  
Alejandro Caceres-Euse ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Caribbean Sea ◽  
High Concentration ◽  
Near Surface ◽  
Relaxation Phase ◽  
Upwelling System ◽  
South Central ◽  
The Caribbean ◽  
Counter Current ◽  
The Impact

The variability of La Guajira upwelling system, in the south-central Caribbean Sea, is strongly influenced by the intensity and location of the atmospheric Caribbean Low-Level Jet (CLLJ), a near-surface branch of the easterlies, as well as by the regional ocean circulation. During favorable conditions (i.e., strong easterlies blowing almost parallel to the coast), upwelling is enhanced and a large amount of primary productivity occurs in La Guajira area. In contrast, during relatively mild wind conditions, the CLLJ is misaligned to the coast and the Caribbean Counter Current (CCC, locally also known as the Darien Current), which forms as a branch from the Panama-Colombia Gyre, flows northeastward over the continental shelf advecting waters from the southwestern Caribbean basin toward La Guajira. The CCC has a clear signature at the surface layer that extends from the Darien Gulf toward La Guajira peninsula during mild wind periods, while disappears during the months of strong winds. The direction and the magnitude of the easterlies, and more specifically of the CLLJ, control the position and pathway of the CCC, which extends more than 900 km in the southern Caribbean Sea during May, June, August, September, and October. The high concentration of chlorophyll-a at the sea surface evidenced by satellite-based color images is semi-seasonally modulated by the CLLJ, which during its relaxation phase allows the irruption of the CCC toward the east up to La Guajira.

Influence of fishers’ behaviour on the catchability of surface tuna schools in the Venezuelan purse-seiner fishery in the Caribbean Sea

1999 ◽  
Vol 56 (3) ◽  
pp. 394-406
Author(s):  
Daniel Gaertner ◽  
Mauricio Pagavino ◽  
Jesus Marcano
Keyword(s):  
Environmental Factors ◽  
Daily Activity ◽  
Caribbean Sea ◽  
Catch Rate ◽  
Causal Network ◽  
Fine Scale ◽  
Network Approach ◽  
Logistic Regressions ◽  
The Caribbean ◽  
The Impact

The influence of Venezuelan skippers' behaviour on the catchability of surface tuna schools was modelled using logistic regressions. Data obtained from observers onboard purse seiners indicated that fishers' fine-scale decisions, such as chasing and setting a school, were influenced by (i) the skipper's skill, (ii) the fishing equipment used (e.g., whether a bird radar was used or not), (iii) the features of the tuna school, and (iv) some environmental factors. The connections among the decisions related to the fishing process and these variables were synthesized in a causal network approach. Results clearly showed that schools (i) composed by fishes under 2 kg and (ii) where biomass was lower than 5 metric tons were disregarded by fishers. Because fishers used these thresholds to decide when to set the net, modifications in their behaviour over the years may introduce serious biases in the analysis of any catch rate and abundance relationship. An average daily activity record of a purse seiner shows the proportion of time spent in searching and in setting activities and highlights the impact that the use of new fishing equipment may have on fishing power.

Assessment of the Effect of Increasing Temperature On the Ecology and Assemblage Structure of Modern Planktic Foraminifers in the Caribbean and Surrounding Seas

2018 ◽  
Vol 48 (3) ◽  
pp. 251-272 ◽  
Author(s):  
Anna Jentzen ◽  
Joachim Schönfeld ◽  
Ralf Schiebel
Keyword(s):  
Surface Waters ◽  
Surface Sediments ◽  
Seawater Temperature ◽  
Chlorophyll Concentration ◽  
Caribbean Sea ◽  
Trophic Conditions ◽  
Near Surface ◽  
The Caribbean ◽  
Standing Stocks ◽  
The 1960S

Abstract Habitat patterns of subtropical and tropical planktic foraminifers in the Caribbean Sea were obtained from plankton samples collected in spring 2009 and 2013. The spatial distribution in surface waters (3.5 m water depth) and depth habitat patterns (surface to 400 m) of 33 species were compared with prevailing water-mass conditions (temperature, salinity, and chlorophyll-a concentration) and planktic foraminiferal test assemblages in surface sediments. Distribution patterns indicate a significant relationship with seawater temperature and trophic conditions. A reduction in standing stocks was observed close to the Orinoco River plume and in the Gulf of Paria, associated with high turbidity and concomitant low surface-water salinity. In contrast, a transient mesoscale patch of high chlorophyll concentration in the eastern Caribbean Sea was associated with higher standing stocks in near surface waters, including high abundances of Globigerinita glutinata and Neogloboquadrina dutertrei. Globorotalia truncatulinoides mainly lives close to the seasonal pycnocline and can be linked to winter conditions indicated by lower sea-surface temperatures (SSTs) of ∼20°C. Globigerinoides sacculifer and Globoturborotalita rubescens were associated with oligotrophic conditions in the pelagic Caribbean Sea during early spring and showed a synodic lunar reproduction cycle. The live assemblages in the water column from 2009 and 2013 were similar to those reported in earlier studies from the 1960s and 1990s and to assemblages of tests in the surface sediments. Minor differences in faunal proportions were attributed to seasonal variability and environmental differences at the local scale. An exception was the low relative abundance of Globigerinoides ruber in the Caribbean Sea in 2009 compared to surface sediment samples and plankton net samples collected in the 1960s and 1990s. Decreasing abundance of Gs. ruber white in the Caribbean Sea may be associated with increasing SSTs over past decades and changes in nutrient flux and primary production.

scholarly journals Arribazones de Sargassum en la costa norte occidental de Cuba

2020 ◽  
Vol 2 (1) ◽  
pp. 19-30
Author(s):  
G. Arencibia-Carballo ◽  
J.M. Irañeta Batallán ◽  
J. Morell ◽  
A.R. Moreira González
Keyword(s):  
Negative Impact ◽  
Caribbean Sea ◽  
Geographic Area ◽  
Tourism Industry ◽  
Caribbean Region ◽  
Western Coast ◽  
Tidal Zone ◽  
The North ◽  
The Caribbean ◽  
The Impact

The pelagic macroalgae finches of the Sargassum genus in the Caribbean Sea currently represent a very natural problem due to their negative impact on the tourism industry, fishing industry, the environment and society in general. This work presents an above report of Sargassum that occurred on the north western coast of the Cuban archipelago in March 2019. The macroalgae species identified in the tidal zone were Sargassum fluitans and S. natans, and the specific geographic area where the impact of the upheaval occurred was from the west of Matan-zas bay to Mariel bay. The finches of these macroalgae were cataloged with a moderate magnitude compared to other reports in the Mexican Caribbean and in the Dominican Republic. This order of magnitude was cataloged based on its covered area of 169.3 km and its distribution along the coast in large patches, but very fragmented, despite the prevailing winds from the first quadrant (from north to east) during this period. Other events of this type reported in Cuba and the Caribbean region are taken up and discussed. Keywords: Caribbean Sea, Sargassum fluitans, Sargassum natans, Cuba.

scholarly journals Assessment of the Canary current upwelling system in a regionally coupled climate model

2021 ◽  
Author(s):  
Ruben Vazquez ◽  
Ivan Parras-Berrocal ◽  
William Cabos ◽  
Dmitry V. Sein ◽  
Rafael Mañanes ◽  
...  
Keyword(s):  
Climate Models ◽  
Coupled Model ◽  
Horizontal Resolution ◽  
Global Climate Models ◽  
Climate Change Signal ◽  
Climate Modelling ◽  
Near Surface ◽  
Upwelling System ◽  
The Impact ◽  
Mesoscale Processes

AbstractThe Canary current upwelling is one of the major eastern boundary coastal upwelling systems in the world, bearing a high productive ecosystem and commercially important fisheries. The Canary current upwelling system (CCUS) has a large latitudinal extension, usually divided into upwelling zones with different characteristics. Eddies, filaments and other mesoscale processes are known to have an impact in the upwelling productivity, thus for a proper representation of the CCUS and high horizontal resolution are required. Here we assess the CCUS present climate in the atmosphere–ocean regionally coupled model. The regional coupled model presents a global oceanic component with increased horizontal resolution along the northwestern African coast, and its performance over the CCUS is assessed against relevant reanalysis data sets and compared with an ensemble of global climate models (GCMs) and an ensemble of atmosphere-only regional climate models (RCMs) in order to assess the role of the horizontal resolution. The coupled system reproduces the larger scale pattern of the CCUS and its latitudinal and seasonal variability over the coastal band, improving the GCMs outputs. Moreover, it shows a performance comparable to the ensemble of RCMs in representing the coastal wind stress and near-surface air temperature fields, showing the impact of the higher resolution and coupling for CCUS climate modelling. The model is able of properly reproducing mesoscale structures, being able to simulate the upwelling filaments events off Cape Ghir, which are not well represented in most of GCMs. Our results stress the ability of the regionally coupled model to reproduce the larger scale as well as mesoscale processes over the CCUS, opening the possibility to evaluate the climate change signal there with increased confidence.

scholarly journals The impact of upwelling on the intensification of anticyclonic ocean eddies in the Caribbean Sea

Ocean Science ◽  
2019 ◽  
Vol 15 (6) ◽  
pp. 1419-1437 ◽  
Author(s):  
Carine G. van der Boog ◽  
Julie D. Pietrzak ◽  
Henk A. Dijkstra ◽  
Nils Brüggemann ◽  
René M. van Westen ◽  
...  
Keyword(s):  
Coastal Upwelling ◽  
Caribbean Sea ◽  
Vertical Shear ◽  
Ekman Transport ◽  
Density Gradients ◽  
River Plumes ◽  
Salinity Gradients ◽  
The Caribbean ◽  
Anticyclonic Eddies ◽  
The Impact

Abstract. The mesoscale variability in the Caribbean Sea is dominated by anticyclonic eddies that are formed in the eastern part of the basin. These anticyclones intensify on their path westward while they pass the coastal upwelling region along the Venezuelan and Colombian coast. In this study, we used a regional model to show that this westward intensification of Caribbean anticyclones is steered by the advection of cold upwelling filaments. Following the thermal wind balance, the increased horizontal density gradients result in an increase in the vertical shear of the anticyclones and in their westward intensification. To assess the impact of variations in upwelling on the anticyclones, several simulations were performed in which the northward Ekman transport (and thus the upwelling strength) is altered. As expected, stronger (weaker) upwelling is associated with stronger (weaker) offshore cooling and a stronger (weaker) westward intensification of the anticyclones. Moreover, the simulations with weaker upwelling show farther advection of the Amazon and Orinoco River plumes into the basin. As a result, in these simulations the horizontal density gradients were predominantly set by horizontal salinity gradients. The importance of the horizontal density gradients driven by temperature, which are associated with the upwelling, increased with increasing upwelling strength. The results of this study highlight that both upwelling and the advection of the river plumes affect the life cycle of mesoscale eddies in the Caribbean Sea.

scholarly journals Radon activity in the lower troposphere and its impact on ionization rate: a global estimate using different radon emissions

2011 ◽  
Vol 11 (15) ◽  
pp. 7817-7838 ◽  
Author(s):  
K. Zhang ◽  
J. Feichter ◽  
J. Kazil ◽  
H. Wan ◽  
W. Zhuo ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Radioactive Decay ◽  
Lower Troposphere ◽  
Atmospheric Model ◽  
Ionization Rate ◽  
Aerosol Size Distribution ◽  
High Concentration ◽  
Near Surface ◽  
Global Estimate ◽  
The Impact

Abstract. The radioactive decay of radon and its progeny can lead to ionization of air molecules and consequently influence aerosol size distribution. In order to provide a global estimate of the radon-related ionization rate, we use the global atmospheric model ECHAM5 to simulate transport and decay processes of the radioactive tracers. A global radon emission map is put together using regional fluxes reported recently in the literature. Near-surface radon concentrations simulated with this new map compare well with measurements. Radon-related ionization rate is calculated and compared to that caused by cosmic rays. The contribution of radon and its progeny clearly exceeds that of the cosmic rays in the mid- and low-latitude land areas in the surface layer. During cold seasons, at locations where high concentration of sulfuric acid gas and low temperature provide potentially favorable conditions for nucleation, the coexistence of high ionization rate may help enhance the particle formation processes. This suggests that it is probably worth investigating the impact of radon-induced ionization on aerosol-climate interaction in global models.

Improving Ocean Circulations Using Lagrangian Data Assimilation of Surface Drifters During Grand Lagrangian Deployments

2021 ◽  
Author(s):  
Luyu Sun ◽  
Stephen Penny ◽  
Matthew Harrison
Keyword(s):  
Data Assimilation ◽  
Ocean Circulation ◽  
World Ocean ◽  
Global Ocean ◽  
Observation System ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Near Surface ◽  
Lagrangian Data ◽  
Surface Drifters ◽  
The Impact

<p>Accurate forecast of ocean circulation is important in many aspects. A lack of direct ocean velocity observations has been one of the overarching issues in nowadays operational ocean data assimilation (DA) system. Satellite-tracked surface drifters, providing measurement of near-surface ocean currents, have been of increasing importance in global ocean observation system. In this work, the impact of an augmented-state Lagrangian data assimilation (LaDA) method using Local Ensemble Transform Filter (LETKF) is investigated within a realistic ocean DA system. We use direct location data from 300 surface drifters released in the Gulf of Mexico (GoM) by the Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CARTHE) during the summer 2012 Grand Lagrangian Deployment (GLAD) experiment. These drifter observations are directly assimilated into a realistic eddy-resolving GoM configuration of the Modular Ocean Model version 6 (MOM6) of the Geophysical Fluid Dynamics Laboratory (GFDL). Ocean states (T/S/U/V) are updated at both the surface and at depth by utilizing dynamic forecast error covariance statistics. Four experiments are conducted: (1) a free run generated by MOM6; 2) a DA experiment assimilating temperature and salinity profile observations from World Ocean Database 2018 (WOD18); and 3) a DA experiment assimilating both drifter and the profile observations. The LaDA results are then compared with the traditional assimilation using the drifter-derived velocity field from the same GLAD database. In addition, we evaluate the impact of the LaDA algorithm on different eddy-permitting and eddy-resolving model resolutions to determine the most effective horizontal resolutions for assimilating drifter position data using LaDA.</p>

scholarly journals The Impact of Upwelling on the Intensification of Anticyclonic Ocean Eddies in the Caribbean Sea

2019 ◽  
Author(s):  
Carine G. van der Boog ◽  
Julie D. Pietrzak ◽  
Henk A. Dijkstra ◽  
Nils Brüggemann ◽  
René M. van Westen ◽  
...  
Keyword(s):  
Coastal Upwelling ◽  
Caribbean Sea ◽  
Vertical Shear ◽  
Ekman Transport ◽  
Density Gradients ◽  
River Plumes ◽  
The Caribbean ◽  
Western Side ◽  
Anticyclonic Eddies ◽  
The Impact

Abstract. The mesoscale variability in the Caribbean Sea is dominated by anticyclonic eddies that are formed in the eastern part of the basin. These anticyclones intensify on their path westward while they pass the coastal upwelling region along the Venezuelan and Colombian coast. In this study, we used a regional model to show that this westward intensification of Caribbean anticyclones is driven by the advection of cold upwelling filaments. These dense filaments are advected by the anticyclones, leading to an increase of the horizontal density gradients at the western side of the anticyclones. Following the thermal wind balance, the increased density gradients result in an increase of the vertical shear of the anticyclones and to their westward intensification. To assess the impact of variations in upwelling on the anticyclones, several simulations were performed in which the northward Ekman transport (and thus the upwelling strength) is altered. As expected, stronger (weaker) upwelling is associated with more stronger (weaker) offshore cooling and a more (less) westward intensification of the anticyclones. The simulations with weaker upwelling show farther advection of the Amazon and Orinoco River plumes into the basin. The dispersion of the river plumes affects the formation process of the anticyclones, where the horizontal density gradients were mainly determined by the salinity gradients of the river plume and not by temperature gradients that were associated with upwelling.

Local Histories/Global Designs

2012 ◽  
Author(s):  
Walter D. Mignolo
Keyword(s):  
Social Sciences ◽  
Central America ◽  
Postcolonial Studies ◽  
The United States ◽  
Philosophy Of History ◽  
South Central ◽  
The Social ◽  
The Caribbean ◽  
Border Thinking ◽  
East West

This book is an extended argument about the “coloniality” of power. In a shrinking world where sharp dichotomies, such as East/West and developing/developed, blur and shift, this book points to the inadequacy of current practices in the social sciences and area studies. It explores the crucial notion of “colonial difference” in the study of the modern colonial world and traces the emergence of an epistemic shift, which the book calls “border thinking.” Further, the book expands the horizons of those debates already under way in postcolonial studies of Asia and Africa by dwelling on the genealogy of thoughts of South/Central America, the Caribbean, and Latino/as in the United States. The book's concept of “border gnosis,” or sensing and knowing by dwelling in imperial/colonial borderlands, counters the tendency of occidentalist perspectives to manage, and thus limit, understanding. A new preface discusses this book as a dialogue with Hegel's Philosophy of History.

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