Ocean Research Articles

The ocean between us.

The ocean between us.

Aprender a interpretar la acidificación oceánica con recursos on-line y experimentación contextualizada

En este artículo se presenta una experiencia de introducción al proceso de acidificación oceánica –disminución del pH del agua del mar– en aulas de Ciencias Experimentales del Grado en Educación Primaria, utilizando recursos on-line y experimentación contextualizada, para contribuir al desarrollo de competencias científicas y formular propuestas de mejora del currículo en el marco de la educación para la sustentabilidad. Se ha contribuido a la adquisición de conocimientos, a la interpretación del proceso estudiado y a la concienciación ambiental. Se han hecho propuestas de mejora del currículo y se han formulado preguntas que darán origen a nuevas investigaciones. Finalmente, se señalan limitaciones de la experiencia relativas a su novedad y a la escasez de recursos didácticos adecuados.

Broad-scale species distribution models applied to data-poor areas

Species distribution models (SDMs) have been increasingly used over the past decades to characterise the spatial distribution and the ecological niche of various taxa. Validating predicted species distribution is important, especially when producing broad-scale models (i.e. at continental or oceanic scale) based on limited and spatially aggregated presence-only records. In the present study, several model calibration methods are compared and guidelines are provided to perform relevant SDMs using a Southern Ocean marine species, the starfish Odontaster validus Koehler, 1906, as a case study. The effect of the spatial aggregation of presence-only records on modelling performance is evaluated and the relevance of a target-background sampling procedure to correct for this effect is assessed. The accuracy of model validation is estimated using k-fold random and spatial cross-validation procedures. Finally, we evaluate the relevance of the Multivariate Environmental Similarity Surface (MESS) index to identify areas in which SDMs accurately interpolate and conversely, areas in which models extrapolate outside the environmental range of occurrence records.Results show that the random cross-validation procedure (i.e. a widely applied method, for which training and test records are randomly selected in space) tends to over-estimate model performance when applied to spatially aggregated datasets. Spatial cross-validation procedures can compensate for this over-estimation effect but different spatial cross-validation procedures must be tested for their ability to reduce over-fitting while providing relevant validation scores. Model predictions show that SDM generalisation is limited when working with aggregated datasets at broad spatial scale. The MESS index calculated in our case study show that over half of the predicted area is highly uncertain due to extrapolation. Our work provides methodological guidelines to generate accurate model assessments at broad spatial scale when using limited and aggregated presence-only datasets. We highlight the importance of taking into account the presence of spatial aggregation in species records and using non-random cross-validation procedures. Evaluating the best calibration procedures and correcting for spatial biases should be considered ahead the modelling exercise to improve modelling relevance.

Andrea Chung: You Broke the Ocean in Half to be Here

Andrea Chung: You Broke the Ocean in Half to be Here

Análise Sinótica de um Período Frio em Bauru - SP em Julho de 2015

Os primeiros dez dias do mes de julho de 2015 em Bauru, SP, apresentaram temperaturas baixas com um declinio mais acentuado no dia 05. Portanto, o objetivo desse estudo foi descrever as caracteristicas da atmosfera que conduziram a esse declinio da temperatura no dia 05. Para isso, utilizaram-se dados da reanalise ERA-Interim com resolucao horizontal de 0,75° x 0,75°. Foram construidas e analisadas as cartas sinoticas de 2 dias antes a dois dias apos o dia de menor temperatura, bem como de outros campos atmosfericos. No periodo que antecede a maior queda de temperatura em Bauru, ha uma onda no escoamento de oeste em 500 hPa que se propaga pelo oceano Pacifico Sul. Quando esse sistema cruza os Andes, ocorre a formacao da onda frontal em superficie que juntamente com o anticiclone migratorio causam adveccao horizontal da massa de ar frio que influenciou o tempo em grande parte do Brasil no inicio do mes de julho de 2015. Considerando o padrao de onda em 500 hPa, a amplificacao da crista pela intensa adveccao quente no lado sudoeste da alta pos-frontal, em conjunto com a reducao da adveccao de vorticidade relativa negativa (positiva) a leste do cavado (crista) e os baixos valores de vorticidade potencial na regiao do cavado tiveram participacao no lento deslocamento da onda, o que contribuiu para a maior permanencia da alta pos-frontal no oceano Atlântico e, portanto, para um predominio do transporte de ar mais frio em direcao ao interior do Estado de Sao Paulo.

Comparação Climatológica do Vento na Superfície do Mar entre Duas Reanálises Atmosféricas Globais para a Margem Continental Leste/Sudeste Brasileira

Devido a relevância do entendimento da influencia dos fluxos atmosfericos sobre o estado do oceano, em especial, a modelagem e previsao das interacoes entre esses dois sistemas, o presente estudo objetivou comparar, climatologicamente, duas reanalises atmosfericas com relacao a energia dos ventos sobre a superficie do mar para margem continental leste/sudeste brasileira. Os produtos selecionados foram o Climate Forecast System Reanalysis (CFSR) e o ERA–Interim (ERAI), comparados entre si de 1979 a 2010 e validados de acordo com os dados remotos do Advanced Scatterometer (ASCAT) entre maio/2007 e dezembro/2010. Os resultados demonstraram claro padrao mais energetico do CFSR em relacao ao ERAI, seja espacial ou temporalmente, excecao feita a certas areas costeiras. Quantitativamente, o primeiro produto, em media, foi 13% mais intenso, bem como apresentou maior energia cinetica em 92% dos meses entre 1979 e 2010. O CFSR e o ERAI superestimaram os dados do ASCAT em 8% e 2%, respectivamente, mas se ajustaram satisfatoriamente bem, com baixos RMSE e altos coeficientes de correlacao. Sugere-se que a maior energia existente no CFSR esteja associada a sua maior resolucao espacial, o que possibilitaria maior amostragem dos fenomenos atmosfericos, e que o melhor ajuste do ERAI seja consequencia de seu metodo de assimilacao de dados mais robusto, o que compensaria a menor disponibilidade de dados in situ e remotos no Atlântico Sul.

Mapping Tertiary mid-ocean ridge subduction and slab window formation beneath Sundaland using seismic tomography

Based on tectonic reconstructions, Whittaker et al. (2007) proposed that a slab window formed beneath Sundaland between 70 and 43 Ma, due to subduction of the Wharton Basin spreading ridge between India and Australia. They suggest that extension in the Java Sea region at this time was exacerbated as a result of upwelling asthenosphere associated with the slab window. Active ridge subduction and subsequent slab window formation can severely affect basin formation, heatflow and petroleum systems development on the overriding margin. A slab window forms between diverging plates when a mid-ocean ridge is subducted, leading to anomalous thermal effects like increased mantle wedge temperatures and thermal gradients in the overlying crust. Whittaker et al.?s (2007) kinematic reconstructions rely on restoring now-subducted lithosphere based on preserved ocean crust, but the inherent uncertainties in this process call for an independent evaluation of this model. Mantle seismic tomography models provide qualitative boundary conditions for modelled tectonic histories. We compare seismic tomography models with the model of Whittaker et al. (2007) at a range of mantle depths to confirm the existence of a slab window, and obtain bounds for its maximum regional extent. We identify a break in the high-velocity, down-going Indian-Australian slab at depths between 950-1350 km and longitudes between 85° and 110°, supporting the presence of a slab window. However, we find that the window is located approximately 5° further north and 10°-15° further west than previously proposed, implying that the Wharton Ridge was subducted farther west than previously suggested.

3D inversion of transient electromagnetic data from the Alvheim field, North Sea

SUMMARY We present a case study leading to the 3D inversion of transient electromagnetic (EM) data for delineating reservoir extent at the Alvheim field in the Norwegian sector of the North Sea. The survey was conducted in July and August 2008 using a two ship operation and ocean bottom cables. One ship laid a receiver cable with 30 receiver nodes on the sea floor. The second ship placed a source cable used to generate a coded transient signal on the sea floor. The configuration of the source and receiver spread was analogous to 2D seismic acquisition, as the system was rolled along to obtain multi-fold coverage of the subsurface. The survey spanned 20 km, resulting in measurements of 1270 source-receiver locations. The electric fields for each source-receiver pair were measured and deconvolved with the source current to determine the impulse response function. Preliminary inversions were made for each source-receiver pair using a 1D model, and the results were stitched to a 2D image. Having defined a background model, all data were then simultaneously inverted in 3D with focusing regularization. This revealed high resistivity volumes corresponding to the known hydrocarbon-bearing reservoirs of the Alvheim field.

First Record of Psolid Sea Cucumber Psolidium (Holothuroidea: Dendrochirotida: Psolidae) from the Brazilian Coast, with the Description of Two New Species.

Two new species, Psolidium nanoplax and Psolidium lonchostinum, are described from the southeastern Brazilian coast, from 44 and 200-258 meters deep, respectively. This is the first record of the genus Psolidium from Brazil. Psolidium nanoplax sp. nov. superficially resembles its Atlantic and Magellanic congeners, P. disciformis (Théel, 1886), P. dorsipes Ludwig, 1886, and P. prostratum Pawson & Valentine, 1981, but it can be readily distinguished from these by a combination of characters of the sole ossicles and by the absence of midventral tube feet. Psolidium lonchostinum n. sp. stands apart from all Atlantic and Southern Ocean species (Atlantic sector), including Psolidium nanoplax sp. nov., in having branched rods (thorn ossicles) and knobbed plates in the sole. A key and a synoptic table to all Atlantic and Southern Ocean (Atlantic sector) species of Psolidium is provided.

Real Time Rendering of Large Scale Realistic Ocean Scenes Driven by Time and Space

Real Time Rendering of Large Scale Realistic Ocean Scenes Driven by Time and Space

An Analysis of Tropical Cyclone Activity over the Western North Pacific in 2011

ABSTRACT This paper uses China Meteorological Administration tropical cyclone (TC) best track data to analyze the characteristics of TC activity over the western North Pacific in 2011. Results derived from two other datasets, issued by the Regional Specialized Meteorological Center Tokyo and the Joint Typhoon Warning Center, were also compared. We show that the annual TC activity in 2011 was weaker than the climatology, and exhibited remarkable intraseasonal signals. The main TC genesis region migrated seasonally between the southwest (7° – 17°N, 120° – 140°E) and northeast (17°–25°N, 135°–165°E) quadrants. Moreover, three prevailing tracks were identified: westward tracks, recurving tracks between 125°–135°E, and northward tracks near 155°E. Special attention was paid to the intra-annual features of TC activity during 2011 and the potential modulators of this activity, including the tropical Indo-Pacific oceans, East Asian Monsoon (EAM), and Intraseasonal Oscillation (ISO). The seasonal migration of the main TC genesis region can be attributed to modulation by the EAM trough and ISO rather than the El Nino-Southern Oscillation. Both the EAM trough and ISO provided favorable conditions, including cyclonic vorticity in the low troposphere, limited vertical shear, and moisture convergence, in both of the main TC genesis quadrants, but unfavorable conditions outside the particular genesis quadrant. Moreover, both EAM and ISO generated a favorable circulation that steered TCs to move along the three prevailing tracks. These findings indicate that TC activity in 2011 was more significantly affected by both the EAM and ISO than by the ENSO.

Non-Face to Face Student Learning Time: An ocean in Medical Education.

doi: https://doi.org/10.12669/pjms.35.3.935

The Sound of an Imitated Ocean

The Sound of an Imitated Ocean

Gem of the Ocean by August Wilson, and: How I Learned What I Learned by August Wilson

Gem of the Ocean by August Wilson, and: How I Learned What I Learned by August Wilson

From the Editor's Desk: Thank the Ocean

From the Editor's Desk: Thank the Ocean

Somewhere in the ocean sinks a schizo

somewhere in the ocean sinks a schizo

A Swirl of Ocean by Melissa Sarno

A Swirl of Ocean by Melissa Sarno

An Ocean of Plastic

An Ocean of Plastic

PALEOGEOGRAPHIC NORTHEASTERN LIMITS OF APHRODINA DUTRUGEI (COCQUAND, 1862) (HETERODONTA, BIVALVIA) FROM THE CENOMANIAN OF THE ARABIAN PLATFORM

The finding of Aphrodina dutrugei (Cocquand, 1862) in a rich collection of non-rudist bivalve fauna from the famous Cenomanian-Turonian carbonates of the Afro-Arabian Plate has permitted the reevaluation of venerid bivalves during an important period of their evolution. The genus Aphrodina Conrad, 1869, Family Veneridae Rafinesque, 1815, embraces several Tethyan Cretaceous species that range from Cenomanian to Santonian. During the late Albian-Maastrichtian ‘Aphrodiniid’ venerids, were distributed along the western margin of the Atlantic (North and South America), the Afro-Arabian Plate (Jordan, SE Turkey, Morocco, Algeria and Egypt), the eastern Tethys, and the Southern Ocean (India, Japan, western Australia and New Zealand). They are also known in the Turonian-Santonian Trans-Saharan Seaway (Gabon). Until now these fossils have been unknown in any Upper Cretaceous localities of southeastern Turkey. In this paper, we report the first record of one of the most common and widespread shallow infaunal species, Aphrodina dutrugei, in the Cenomanian Derdere Formation in the Mardin-Mazidagi area, SE Turkey, which is in the extreme northeastern part of its known range.

Observations of iodine oxide in the Indian Ocean marine boundary layer: A transect from the tropics to the high latitudes

Abstract Observations of iodine oxide (IO) were made in the Indian Ocean and the Southern Ocean marine boundary layer (MBL) during the 8th Indian Southern Ocean Expedition. IO was observed almost ubiquitously in the open ocean with larger mixing ratios south of the Polar Front (PF). Contrary to previous reports, IO was not positively correlated to sea surface temperature (SST)/salinity, or negatively to chlorophyll a. Over the whole expedition, SST showed a weak negative correlation with respect to IO while chl a was positively correlated. North of the PF, chl a showed a strong positive correlation with IO. The computed HOI and I2 fluxes do not show any significant correlation with atmospheric IO. Simulations with the global CAM-Chem model show a reasonably good agreement with observations north of the PF but the model fails to reproduce the elevated IO south of the PF indicating that the current emission parametrizations are not sufficient to explain iodine chemistry in the Southern Indian Ocean.