Time filter

Source Type

Le Touquet – Paris-Plage, France

Letetrel C.,University of La Rochelle | Marcos M.,CSIC - Mediterranean Institute for Advanced Studies | Martin Miguez B.,Intergovernmental Oceanographic Commission of UNESCO | Woppelmann G.,University of La Rochelle
Continental Shelf Research | Year: 2010

Sea level extremes and their temporal variability have been explored based on the hourly measurements at Marseille tide gauge for the period 1885-2008. A careful quality check has first been applied to the observations to ensure consistency of the record by eliminating outliers and datum shifts. Yearly percentiles have been used to investigate long-term trends of extremes revealing that secular variations in extremes are linked to mean sea level changes. The associated decadal changes show discrepancies between mean sea level trend and extreme fluctuations, due to the influence of the atmospheric forcing. A local regression model based on the generalized Pareto distribution has been applied to derive trends in return levels. The 50-years return levels reach values between 80 and 120. cm. The most significant changes in return levels are characterized by an increase since the 1970s. © 2010 Elsevier Ltd. Source

Villamor B.,Spanish Institute of Oceanography | Gonzalez-Pola C.,Spanish Institute of Oceanography | Lavin A.,Spanish Institute of Oceanography | Valdes L.,Intergovernmental Oceanographic Commission of UNESCO | And 9 more authors.
Fisheries Oceanography | Year: 2011

We investigate the effect of strong meteorological perturbations in early spring on the success of mackerel (Scomber scombrus) recruitment in the N/NW Iberian area (southern Bay of Biscay) for the period 1999-2008. In 2000, the year of the most pronounced recruitment failure on record, two consecutive multidisciplinary surveys sampled hydrographic conditions and mackerel eggs, larvae and post-larvae over the main mackerel spawning grounds of the north and northwest coast of the Iberian Peninsula. Analysis of egg and larval abundance and birthdates based on the otoliths of mackerel juveniles caught between July and October 2000 showed that there were no survivors from the early spring spawns, indicating a massive loss of early spawning effort. Moreover, the abundance of 1-year-old mackerel estimated from an acoustic survey carried out in 2001 was the lowest observed within the 1999-2008 time series. This low or null survival from the early spawns in 2000 could be due to the meteorological and oceanographic conditions of that spring, in particular two storm events in April after a relatively calm March. The first storm event from the north caused strong local wind in the southern Bay of Biscay but a weak oceanographic response. The second storm event from the southwest was mainly felt west of Galicia and caused a notable increase in shelf currents and a shift of the hydrographical structure along the shelf. Detailed analysis of strong wind pulses in early spring within the historical recruitment record suggests that strong local turbulence generated by high wind speeds and advection of larvae caused by the enhancement of shelf currents can contribute to reduced recruitment. Our observations indicate that, in 2000, both mechanisms were present. © 2011 Blackwell Publishing Ltd. Source

Valsala V.,Indian Institute of Tropical Meteorology | Maksyutov S.,Japan National Institute of Environmental Studies | Telszewski M.,Intergovernmental Oceanographic Commission of UNESCO | Nakaoka S.,Japan National Institute of Environmental Studies | And 3 more authors.
Biogeosciences | Year: 2012

Some dominant spatial and temporal structures of the North Pacific air-sea CO2 fluxes in response to the Pacific Decadal Oscillation (PDO) are identified in three data products from three independent sources: an assimilated CO2 flux product and two forward model solutions. The interannual variability of CO2 flux is found to be an order of magnitude weaker compared to the seasonal cycle of CO2 flux in the North Pacific. A statistical approach is employed to quantify the signal-to-noise ratio in the reconstructed dataset to delineate the representativity errors. The dominant variability with a signal-to-noise ratio above one is identified and its correlations with PDO are examined. A tentative four-pole pattern in the North Pacific air-sea CO2 flux variability linked to PDO emerges in which two positively correlated poles are oriented in the northwest and southeast directions and contrarily, the negatively correlated poles are oriented in the northeast and southwest directions. This pattern is identified in three products, providing CO2 and pCO2. Its relations to the interannual El Niño-Southern Oscillation (ENSO) and lower-frequency PDO are separately identified. A combined EOF analysis between air-sea CO2 flux and key variables representing ocean-atmosphere interactions is carried out to elicit robust oscillations in the North Pacific CO2 flux in response to the PDO. The proposed spatial and temporal structures of the North Pacific CO2 fluxes are insightful since they separate the secular trends of the surface ocean carbon from the interannual variability. The regional characterization of the North Pacific in terms of PDO and CO2 flux variability is also instructive for determining the homogeneous oceanic domains for the Regional Carbon Cycle and Assessment Processes (RECCAP). © 2012 Author(s). Source

Wiebe P.H.,Woods Hole Oceanographic Institution | Harris R.,Plymouth Marine Laboratory | Gislason A.,Iceland Marine Research Institute | Margonski P.,Polish National Marine Fisheries Research Institute | And 5 more authors.
Progress in Oceanography | Year: 2016

The ICES Study Group on Zooplankton Ecology was created in 1991 to address issues of current and future concern within the field of zooplankton ecology. Within three years it became the ICES Working Group on Zooplankton Ecology (ICES WGZE) and this unique group in the world's oceanographic community has now been active for 25 years. This article reviews and synthesizes the products, and major accomplishments of the group. Achievements of the group, including the Zooplankton Methodology Manual, the Zooplankton Status Reports, and the International Zooplankton Symposia, have had an important impact on the wider field. Among the future issues that remain to be addressed by the group are the assessment of exploratory fisheries on zooplankton and micronekton species; further development of the zooplankton time-series; compilation and integration of allometric relationships for zooplankton species, and evaluation of new methodologies for the study of zooplankton distribution, abundance, physiology, and genetics. Marine science is an increasingly global undertaking and groups such as the ICES WGZE will continue to be essential to the advancement of understanding of zooplankton community structure and population dynamics in the world's oceans. © 2015 Elsevier Ltd. Source

Bernal M.,Spanish Institute of Oceanography | Bernal M.,Rutgers University | Stratoudakis Y.,Instituto Nacional Of Recursos Biologicos Inrb Ipimar | Wood S.,University of Bath | And 4 more authors.
ICES Journal of Marine Science | Year: 2011

Assumptions of daily spawning synchronicity and estimation of egg mortality for Atlanto-Iberian sardine are revised in the context of daily estimators of egg production. An extensive database of ichthyoplankton surveys from 1985 to 2008, aggregated at different levels, is used, a set of mortality models is derived, and a comparison among them is carried out using standard statistical techniques. Analysis of the database shows Atlanto-Iberian sardine to be a late-evening spawner, in agreement with previous knowledge, but suggests a lengthier daily period of spawning. Comparison among the set of mortality models used suggests that estimates of mortality from single surveys for Atlanto-Iberian sardine are often unreliable, and that the mean estimates obtained after aggregating data from various years are statistically significant, more robust, and in line with existing information gathered from the literature. © 2011 International Council for the Exploration of the Sea. Published by Oxford Journals. All rights reserved. Source

Discover hidden collaborations