Klimaservice für die Klimafolgen- und Anpassungsforschung in der Metropolregion Hamburg

Vorstellung von Projektergebnissen aus KLIMZUG-NORD bezüglich jährliche und saisonale Temperatur- und Niederschlagsänderungen zur Mitte und Ende des 21. Jahrhunderts, sowie Ergebnisse aus dem Projekt Hamburg 2K. In Hamburg 2K wird analysiert, was eine Begrenzung auf eine Temperaturänderung von 2K für Hamburg bedeutet. Ausgewertet wurden Temperatur- und Niederschlagsänderungen sowie ausgewählte Indices

Auswirkungen des globalen Klimawandels auf Extremwasserstände in der Nordsee

Vorhersage und ProjektionEffekte des Klimawandels in der Atmosphäre und im Ozean können das Risiko von lokalen Sturmfluten oder Hochwasserereignissen in Flüssen und Ästuaren potentiell erhöhen. Basierend auf Modellergebnissen von hoch-aufgelösten Klimaprojektionen für das 21. Jahrhundert sollen sowohl Antriebsmechanismen und dominierende Variabilitätsmoden von extrem hohen Pegelständen an der kontinentalen Nordseeküste als auch mögliche zukünftige Änderungen in der Dynamik damit verbundener Wetterverhältnisse identifiziert werden. Der Schwerpunkt liegt dabei in der Untersuchung des Wechselspiels von extern und intern generierten Sturmfluten, Gezeitenströmungen sowie hydro-meteorologischen Ereignissen, welche erstmalig mittels eines regional gekoppelten (Atmosphäre-Ozean) Klimamodells konsistent simuliert werden können. Die besondere Eignung des verwendeten Modellsystems wurde in Lang et al. (2019) demonstriert: Wiederkehrpegelstände in der Deutschen Bucht, simuliert für das vergangene Jahrtausend, zeigen gute Übereinstimmung mit Beobachtungswerten der letzten 100 Jahre. Statistische Unsicherheiten bezüglich angewendeter Extremwertstatistiken werden durch das große Ensemble mit 30 Realisationen reduziert. Über eine große Bandbreite räumlicher und zeitlicher Skalen werden anthropogen induzierte Klimaänderungssignale und die natürliche Variabilität des dynamischen Systems analysiert. Die Ergebnisse sollen auch dazu verwendet werden, Hypothesen über zukünftige klimabedingte Änderungen zu testen, welche durch Extrapolation aus Beobachtungsdaten abgeleitet wurden. Unsere noch laufenden Simulationen sind in der Klimaforschung bisher einzigartig aufgrund der Kombination von hoher räumlicher und zeitlicher Auflösung (bis zu 5 km Ozean, 25 km Atmosphäre, 1-stündlicher Output), der interaktiven Kopplung zwischen Atmosphäre, Ozean und Land, der Ensemble-Größe und der transienten Simulation des Zeitraumes 1950-2100 (2006-2100 auf Basis RCP 8.5). Die Modellergebnisse werden auch in Zusammenarbeit mit anderen Wissenschaftlern des BMBF-finanzierten Projektes ClimXtreme erstellt und analysiert. Mit unserem Beitrag wollen wir dieses Projekt, unsere Vorgehensweise und erste Ergebnisse vorstellen

twoPhaseInterTrackFoam: an OpenFOAM module for Arbitrary Lagrangian/Eulerian Interface Tracking with Surfactants and Subgrid-Scale Modeling

We provide an implementation of the unstructured Finite-Volume Arbitrary Lagrangian / Eulerian (ALE) Interface-Tracking method for simulating incompressible, immiscible two-phase flows as an OpenFOAM module. In addition to interface-tracking capabilities that include tracking of two fluid phases, an implementation of a Subgrid-Scale (SGS) modeling framework for increased accuracy when simulating sharp boundary layers is enclosed. The SGS modeling framework simplifies embedding subgrid-scale profiles into the unstructured Finite Volume discretization. Our design of the SGS model library significantly simplifies adding new SGS models and applying SGS modeling to Partial Differential Equations (PDEs) in OpenFOAM

Benthic ecosystem functioning under climate change: modelling the bioturbation potential for benthic key species in the southern North Sea

publishedVersio

Unstructured Finite-Volume Arbitrary Lagrangian / Eulerian Interface Tracking computational framework for incompressible two-phase flows with surfactants (presentation)

Presentation at the APS 76th Annual Meeting of the Division of Fluid Dynamics (DFD23) and Presentation at the GAMM 94th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM 2024)We present an open-source computational framework that implements the unstructured Finite-Volume Arbitrary Lagrangian / Eulerian (ALE) Interface Tracking method for incompressible two-phase flows with surfactants. The framework implements the Interface Tracking ALE method for incompressible two-phase flows using a segregated solution algorithm for solving coupled Navier-Stokes equations with interfacial jump conditions. The Finite Area method discretizes transport equations on curved and evolving fluid interfaces. The open-source implementation as an OpenFOAM module also contains the Sub-Grid-Scale (SGS) model for handling extremely narrow boundary layers of passively transported scalars with very small diffusivity. The SGS model significantly reduces resolution requirements for species transport across the fluid interface. The surface and bulk transport of surfactants and the SGS model are verified using (semi-)analytical verification cases. We also discuss complex setups, e.g., of a rising bubble at high Peclet-numbers under the influence of soluble surfactants

Social competence improves the performance of biomimetic robots leading live fish

Collective motion is commonly modeled with static interaction rules between agents. Substantial empirical evidence indicates, however, that animals may adapt their interaction rules depending on a variety of factors and social contexts. Here, we hypothesized that leadership performance is linked to the leader's responsiveness to the follower's actions and we predicted that a leader is followed longer if it adapts to the follower's avoidance movements. We tested this prediction with live guppies that interacted with a biomimetic robotic fish programmed to act as a 'socially competent' leader. Fish that were avoiding the robot were approached more carefully in future approaches. In two separate experiments we then asked how the leadership performance of the socially competent robot leader differed to that of a robot leader that either approached all fish in the same, non-responsive, way or one that did change its approach behavior randomly, irrespective of the fish's actions. We found that (1) behavioral variability itself appears attractive and that socially competent robots are better leaders which (2) require fewer approach attempts to (3) elicit longer average following behavior than non-competent agents. This work provides evidence that social responsiveness to avoidance reactions plays a role in the social dynamics of guppies. We showcase how social responsiveness can be modeled and tested directly embedded in a living animal model using adaptive, interactive robots

Unstructured Finite-Volume Arbitrary Lagrangian / Eulerian Interface Tracking computational framework for incompressible two-phase flows with surfactants (presentation)

Presentation at the APS 76th Annual Meeting of the Division of Fluid Dynamics (DFD23)We present an open-source computational framework that implements the unstructured Finite-Volume Arbitrary Lagrangian / Eulerian (ALE) Interface Tracking method for incompressible two-phase flows with surfactants. The framework implements the Interface Tracking ALE method for incompressible two-phase flows using a segregated solution algorithm for solving coupled Navier-Stokes equations with interfacial jump conditions. The Finite Area method discretizes transport equations on curved and evolving fluid interfaces. The open-source implementation as an OpenFOAM module also contains the Sub-Grid-Scale (SGS) model for handling extremely narrow boundary layers of passively transported scalars with very small diffusivity. The SGS model significantly reduces resolution requirements for species transport across the fluid interface. The surface and bulk transport of surfactants and the SGS model are verified using (semi-)analytical verification cases. We also discuss complex setups, e.g., of a rising bubble at high Peclet-numbers under the influence of soluble surfactants

Interactive effects of multiple stressors in coastal ecosystems

Coastal ecosystems are increasingly experiencing anthropogenic pressures such as climate heating, CO2 increase, metal and organic pollution, overfishing and resource extraction. Some resulting stressors are more direct like fisheries, others more indirect like ocean acidification, yet they jointly affect marine biota, communities and entire ecosystems. While single-stressor effects have been widely investigated, the interactive effects of multiple stressors on ecosystems are less researched. In this study, we review the literature on multiple stressors and their interactive effects in coastal environments across organisms. We classify the interactions into three categories: synergistic, additive, and antagonistic. We found phytoplankton and mollusks to be the most studied taxonomic groups. The stressor combinations of climate warming, ocean acidification, eutrophication, and metal pollution are the most critical for coastal ecosystems as they exacerbate adverse effects on physiological traits such as growth rate, basal respiration, and size. Phytoplankton appears to be most sensitive to interactions between metal and nutrient pollution. In nutrient-enriched environments, the presence of metals considerably affects the uptake of nutrients, and increases respiration costs and toxin production in phytoplankton. For mollusks, warming and low pH are the most lethal stressors. The combined effect of heat stress and ocean acidification leads to decreased growth rate, shell size, and acid-base regulation capacity in mollusks. However, for a holistic understanding of how coastal food webs will evolve with ongoing changes, we suggest more research on ecosystem-level responses. This can be achieved by combining in-situ observations from controlled environments (e.g. mesocosm experiments) with modelling approaches