Lagrangian circulation and transports of the Antarctic Intermediate Water in the South and tropical Atlantic

This study uses a data set of 611 float years in the south and tropical Atlantic to describe the flow of Antarctic Intermediate Water (AAIW). The data set includes pop-up and acoustically tracked floats that drifted within more than one decade in the area 60 degrees W to 30 degrees E and 70 degrees S to 10 degrees N. Float data is constrained in the vertical according to two isoneutral surfaces (gn = 27.25 and gn = 27.55), according to the characteristics of AAIW. Velocity space-time averages are calculated for various grid resolutions and with cells deformed to match the bathymetry, f/H or f/h (with H being the water depth and h being the thickness of the AAIW layer). Judged by the degree of alignment between respective isolines and the resulting average velocity fields, the best grid is based on a cell size of 3 degrees (latitude) by 4 degrees (longitude) with cells deformed according to f/h. Using this grid, objectively estimated mean currents (and their associated errors), as well as meridional and zonal volume transports are estimated. Since these space-time averages and the corresponding objective maps were unable to reveal the Intermediate Western Boundary Current (iWBC), an alternative approach based on an objective mapping with primal data in overlapping subsets was also applied. With this goal, an isotropic longitudinal covariance function was estimated considering cyli

Spatially resolved past and projected changes of the suitable thermal habitat of North Sea cod (Gadus morhua) under climate change

x,298 p. : il.; 23 cm

A multi-decadal meridional displacement of the Subpolar Front in the Newfoundland Basin

Observations since the 1950s show a multi-decadal cycle of a meridional displacement of the Subpolar Front (SPF) in the Newfoundland Basin (NFB) in the North Atlantic. The SPF displacement is associated with corresponding variations in the path of the North Atlantic Current. We use the ocean general circulation model MPIOM with enhanced horizontal and vertical resolutions and forced with NCEP/NCAR reanalysis data to study the relation of the SPF displacement to atmospheric forcing, intensities of the subpolar gyre (SPG) and Meridional Overturning Circulation (MOC), and Labrador Sea Water (LSW) volume. The simulations indicate that the SPF displacement is associated with a circulation anomaly between the SPG and the subtropical gyre (STG), an inter-gyre gyre with a multi-decadal time scale. A sensitivity experiment indicates that both wind stress curl (WSC) and heat fluxes (which match LSW changes) contribute to the circulation anomalies in the frontal region and to the SPF displacement. An anticyclonic inter-gyre gyre is related to negative WSC and LSW anomalies and to a SPF north of its climatological position, indicating an expanding STG. A cyclonic inter-gyre gyre is related to positive WSC and LSW anomalies and a SPF south of its climatological position, indicating an expanding SPG. Therefore, the mean latitudinal position of the SPF in the NFB (a "SPF index") could be an indicator of the amount of LSW in the inter-gyre region. Spreading of LSW anomalies intensifies the MOC, suggesting our SPF index as predictor of the MOC intensity at multi-decadal time scales. The meridional displacement of the SPF has a pronounced influence on the meridional heat transport, both on its gyre and overturning components.<br

Lagrangesche Zirkulation und Transporte des Antarktischen Zwischenwassers im Südatlantik und tropischen Atlantik

This study uses a data set of 611 float years in the south and tropical Atlantic to describe the flow of Antarctic Intermediate Water (AAIW). The data set includes pop-up and acoustically tracked floats that drifted within more than one decade in the area 60 degrees W to 30 degrees E and 70 degrees S to 10 degrees N. Float data is constrained in the vertical according to two isoneutral surfaces (gn = 27.25 and gn = 27.55), according to the characteristics of AAIW. Velocity space-time averages are calculated for various grid resolutions and with cells deformed to match the bathymetry, f/H or f/h (with H being the water depth and h being the thickness of the AAIW layer). Judged by the degree of alignment between respective isolines and the resulting average velocity fields, the best grid is based on a cell size of 3 degrees (latitude) by 4 degrees (longitude) with cells deformed according to f/h. Using this grid, objectively estimated mean currents (and their associated errors), as well as meridional and zonal volume transports are estimated. Since these space-time averages and the corresponding objective maps were unable to reveal the Intermediate Western Boundary Current (iWBC), an alternative approach based on an objective mapping with primal data in overlapping subsets was also applied. With this goal, an isotropic longitudinal covariance function was estimated considering cyli

A GIS modelling framework to evaluate marine spatial planning scenarios: Co-location of offshore wind farms and aquaculture in the German EEZ

The concept of co-location of marine areas receives an increased significance in the light of sustainable development in the already heavily used offshore marine realm. Within this study, different spatial co-location scenarios for the coupling of offshore aquacultures and wind farms are evaluated in order to support efficient and sustainable marine spatial management strategies. A Geographic Information System (GIS) and multi-criteria evaluation (MCE) techniques were combined to index suitable co-sites in the German exclusive economic zone of the North Sea. The MCE was based on criteria such as temperature, salinity or oxygen. In total, 13 possible aquaculture candidates (seaweed, bivalves, fish and crustaceans) were selected for the scenario configuration. The GIS modelling framework proved to be powerful in defining potential co-location sites. The aquaculture candidate oarweed (Laminaria digitata) revealed the highest suitability scores at 10–20 m depth from April to June, followed by haddock (Melanogrammus aeglefinus) at 20–30 m depth and dulse (Palmaria palmata) and Sea belt (Saccharina latissima) at 0–10 m depth between April and June. In summary, results showed several wind farms were de facto suitable sites for aquaculture since they exhibited high suitability scores for Integrated Multi-Trophic Aquaculture (IMTA) systems combining fish species, bivalves and seaweeds. The present results illustrate how synergies may be realised between competing needs of both offshore wind energy and offshore IMTA in the German EEZ of the North Sea. This might offer guidance to stakeholders and assist decision-makers in determining the most suitable sites for pilot projects using IMTA techniques

Global ocean biogeochemistry model HAMOCC: Model architecture and performance as component of the MPI-Earth System Model in different CMIP5 experimental realizations

Ocean biogeochemistry is a novel standard component of fifth phase of the Coupled Model Intercomparison Project (CMIP5) experiments which project future climate change caused by anthropogenic emissions of greenhouse gases. Of particular interest here is the evolution of the oceanic sink of carbon and the oceanic contribution to the climate-carbon cycle feedback loop. The Hamburg ocean carbon cycle model (HAMOCC), a component of the Max Planck Institute for Meteorology Earth system model (MPI-ESM), is employed to address these challenges. In this paper we describe the version of HAMOCC used in the CMIP5 experiments (HAMOCC 5.2) and its implementation in the MPI-ESM to provide a documentation and basis for future CMIP5-related studies. Modeled present day distributions of biogeochemical variables calculated in two different horizontal resolutions compare fairly well with observations. Statistical metrics indicate that the model performs better at the ocean surface and worse in the ocean interior. There is a tendency for improvements in the higher resolution model configuration in representing deeper ocean variables; however, there is little to no improvement at the ocean surface. An experiment with interactive carbon cycle driven by emissions of CO2 produces a 25% higher variability in the oceanic carbon uptake over the historical period than the same model forced by prescribed atmospheric CO2 concentrations. Furthermore, a climate warming of 3.5 K projected at atmospheric CO2 concentration of four times the preindustrial value, reduced the atmosphere-ocean CO2 flux by 1 GtC yr−1. Overall, the model shows consistent results in different configurations, being suitable for the type of simulations required within the CMIP5 experimental desig

PREFACE MS45 report : pelagic fish and prey field dynamics in their habitat

This milestone report contains an update on the analysis of Yellowfin tuna (YFT) bioclimatic modelling as well as the synthesis based on D12.2 and MS42. Local Yellowfin tuna (Thunnus albacares, YFT) catch rates covering the area 10-20°N latitude and 10-30°W longitude were analysed to indicate catch opportunities in Cape Verde waters. Local catch-per-unit-effort (CPUEl) is treated as a function of stock size, Ns, and environmental factors, Vi, the latter at local scale or at stock scale in terms of climate indices. Of the two indices applied to indicate stock size, i.e. the Japanese long line stock index (LLindex) and the so-called Index4 series, the LLindex

Rapport PREFACE MS45 : dynamique des poissons pélagiques et des champs de proies dans leur habitat

This milestone report contains an update on the analysis of Yellowfin tuna (YFT) bioclimatic modelling as well as the synthesis based on D12.2 and MS42. Local Yellowfin tuna (Thunnus albacares, YFT) catch rates covering the area 10-20°N latitude and 10-30°W longitude were analysed to indicate catch opportunities in Cape Verde waters. Local catch-per-unit-effort (CPUEl) is treated as a function of stock size, Ns, and environmental factors, Vi, the latter at local scale or at stock scale in terms of climate indices. Of the two indices applied to indicate stock size, i.e. the Japanese long line stock index (LLindex) and the so-called Index4 series, the LLindex.Ce rapport d'étape contient une mise à jour de l'analyse de la modélisation bioclimatique du thon à nageoires jaunes (YFT) ainsi que la synthèse basée sur D12.2 et MS42. Les taux de capture locaux de l'albacore (Thunnus albacares, YFT) couvrant la zone de 10-20° de latitude nord et de 10-30° de longitude ouest ont été analysés pour indiquer les possibilités de capture dans les eaux du Cap-Vert. La capture locale par unité d'effort (CPUEl) est traitée en fonction de la taille du stock, Ns, et des facteurs environnementaux, Vi, ces derniers à l'échelle locale ou à l'échelle du stock en termes d'indices climatiques. Parmi les deux indices appliqués pour indiquer la taille des stocks, à savoir l'indice japonais des stocks de poissons à long terme (LLindex) et la série dite "Index4", le LLindex