1,721,443 research outputs found
SFB754 Hydrochemical measurements from water samples
No full textNutrient, transient tracer and N2O water column measurement
An Internally Consistent Dataset of delta13C-DIC in the North Atlantic Ocean - NAC13v1
No full textThe stable carbon isotope composition of dissolved inorganic carbon (δ13C-DIC) can be used to quantify fluxes within the carbon system. For example, knowing the δ13C signature of the inorganic carbon pool can help in describing the amount of anthropogenic carbon in the water column. The measurements can also be used for evaluating modeled carbon fluxes, for making basin-wide estimates of anthropogenic carbon, and for studying seasonal and interannual variability or decadal trends in interior ocean biogeochemistry. For all these purposes, it is not only important to have a sufficient amount of data, but these data must also be internally consistent and of high quality.
In this study, we present a δ13C-DIC dataset for the North Atlantic which has undergone secondary quality control. The data originate from oceanographic research cruises between 1981 and 2014. During a primary quality control step based on simple range tests, obviously bad data were flagged. In a second quality control step, biases between measurements from different cruises were quantified through a crossover analysis using nearby data of the respective cruises, and values of biased cruises were adjusted in the data product. The crossover analysis was possible for 24 of the 32 cruises in our dataset, and adjustments were applied to 11 cruises. The internal accuracy of this dataset is 0.017 ‰
Evaluation of methodologies for inferring temporal changes of oceanic respiration and ventilation under changing climate
Full text linkObservations suggest that the dissolved oxygen inventory in the ocean has declined by over 2% since the middle of the 20th century. Such rapidly ongoing ocean deoxygenation raises concerns of widespread ocean anoxia associated with major mass extinction under a warming climate. Mechanistically understanding ocean deoxygenation requires quantifying the temporal change of ocean ventilation and respiration. However, direct measurements of these processes are very sparse due to methodological limitations. Therefore, indirect measurements based on available measurements are commonly used to estimate the aerobic respiration rates (oxygen utilization rate, OUR) and ventilation strength (Inverse Gaussian Transit Time Distribution, IG-TTD) in the real ocean. This thesis evaluates their reliability in detecting temporal changes. The results discussed in this thesis lead to the overall conclusion that in regions where different water masses mix, both OUR and IG-TTD cannot estimate robust mean state and temporal change of respiration rates and seawater age due to inherent imperfect assumptions. However, in the North Atlantic, OUR and the mean age of IG-TTD robustly reconstruct the temporal change of respiration rates and seawater age as inferred from model results. Current analysis of water age from decades of measurements suggests that intermediate water has become younger while the deep ocean has become older. Models suggest the slowing-down ventilation in the deep ocean will continue for centuries even if carbon dioxide emission stops today, and deep ocean deoxygenation seems unavoidable
Shipboard acoustic doppler current profiling during METEOR cruise M84/3, link to NetCDF file
No full textShipboard acoustic doppler current profiling during METEOR cruise M84/3, link to NetCDF fil
Mit Rennyachten Daten jagen – Neue Wege in der Beobachtung der Ozeane
No full textDie Ozeane produzieren Sauerstoff, sie beeinflussen das Klima und sie liefern Nahrung für viele Menschen. Auf der anderen Seite sind sie durch Erwärmung, Versauerung und Verschmutzung bedroht. Welche Folgen das im Detail haben wird, lässt sich oft nur schwer abschätzen. Es gibt immer noch zu wenig Beobachtungsdaten aus besonders abgelegenen Regionen der Weltmeere und aus ihrem Inneren. Deshalb sind derzeit international zahleiche Großprojekte am Start, um die Ozeanbeobachtung zu intensivieren und besser zu koordinieren.
In dem Vortrag „Mit Rennyachten Daten jagen – Neue Wege in der Beobachtung der Ozeane“ stellen Dr. Toste Tanhua und Dr.-Ing. Sören Gutekunst den aktuellen Stand der internationalen Ozeanbeobachtung vor. An einem eigenen Projekt zeigen sie beispielhaft, dass die Forschung dabei auch ungewöhnliche Wege geht. Die Wissenschaftler des GEOMAR und des Exzellenzclusters "Ozean der Zukunft" haben in Kooperation mit Kieler Firmen und eine Renn-Segelyacht des Volvo Ocean Race mit Sensoren ausgestattet, die Daten zu Physik und zur Chemie des Meerwassers sowie zur Verteilung von Mikroplastik im Ozean entlang der Regattarouten liefern
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