R11: Vorhersagen über den Ozean

Improved sea-floor representations in ocean models
mehr lesen The topographical structure of the sea floor in fluences the dynamics of the ocean heavily, both on the global and on the regional scale. Ocean ridges and gaps determine the propagation of deep and bottom waters. This has a direct impact on the global spreading of heat and salt, and therefore the global climate. However, the accuracy of available ocean models to represent flow phenomena near the sea floor is still very poor due to the traditional representation of bottom topography. This PhD project faces this problem and aims to substantially improve the topographic representation of the Kiel Climate Model (KCM), especially in areas with large gradients. This improvement is important, for instance, to increase the accuracy of the ocean model with respect to the overflow of the Greenland-Scotland ridge and the spreading of deep and bottom water masses from polar regions into the Atlantic Ocean. This propagation in the deep Atlantic influences the meridional overturning (AMOC) and, hence, the entire climate system on the time scale of decades and longer.

Optimal experimental design in marine research
Joscha Reimer,  mehr lesen In marine research, as in many other areas, models are a fundamental concept. Models are essential for predictions and control purposes. They are obtained, improved and verified by measurements of the modelled entity.These measurement results are usually obtained within one or more experiments. As an experiment we identify any process which is at least partially controlled by the researcher and results in a collection of data. Controllable conditions are usually where and when measurements are performed. Sometimes initial conditions and the temporal control of the experiment can also be influenced. Examples for that are the quantity of substances and initial temperature at chemical experiments and there temporal changes. All the controllable conditions of an experiment are summarized as the corresponding experimental design. The experimental design crucially affects the information content of the measurement results. Depending on the purpose of the measurements the experimental design can be optimized to gain the maximum of information. As a result fewer measurements and experiments are conducted to obtain sufficient information. Thus time, money and effort can be saved. There are mainly two types of purposes in respect to which the experimental design is optimized. One major purpose of measurement results is to determine unknown parameters in models. The experimental design for these measurements can be optimized to determine the parameters as good as possible. Another purpose is to choose the most realistic model of a set of potential models. This process is called model discrimination. For that the experimental design can be optimized in such a way that the most realistic model can be determined as clearly as possible.

Southern ocean CO2 uptake in high-reolution ocean-biogeochemistry simulations for the 20th and 21st centuries
Dr. Lavinia Patara,  mehr lesen The proposed project addresses a key challenge in our understanding of the future evolution of the Earth’s oceans and climate. Atmospheric concentrations of CO2, a strong greenhouse gas, are determined not only by anthropogenic carbon emissions but also by ocean uptake of CO2. This project focuses on the Southern Ocean CO2 uptake using global ocean-biogeochemistry simulations for the 20th and 21st centuries. The Southern Ocean is of unique importance for air-sea CO2 exchanges at a global scale due to its vigorous meridional overturning circulation and CO2 uptake potential. Yet there is still large uncertainty regarding ist role in the ocean CO2 uptake in both present climate and for the next century. One reason for this is the lack of explicit simulation of ocean mesoscale eddies within climate-carbon cycle projections. Mesoscale eddies, i.e. small-scale rings shed by current instabilities, are known to be critical in determining the redistribution of tracers within the Southern Ocean. This project will assess the role of Southern Ocean mesoscale eddies on the ocean uptake of CO2 and on its ventilation pathways under present climate and under anthropogenic warming projections for the 21st century. Today’s supercomputing resources are still not sufficient to simulate ocean biogeochemistry in an eddy-resolving global model. Here an innovative “two-way” nesting technique will thus be used to enhance the ocean model resolution over key areas of Southern Ocean airsea CO2 exchange. The model framework will be further developed to include an inorganic carbonate chemistry module. A set of simulations using different ocean resolutions and atmospheric forcing will assess the role of mesoscale eddies on the ocean CO2 uptake in a changing climate. Because of the global scope of the simulations, not only the Southern Ocean CO2 uptake, but also i) other ocean regions and ii) other anthropogenic impacts on the ocean (e.g. sea level changes and ocean acidification) can be investigated.

Surrogate-based Optimization for Marine Biochemical Models
Dr. Iris Kriest,  mehr lesen Marine biogeochemical models are of great importance for a quantitative understanding of the ocean’s role in the global carbon cycle and are essential for projections of the oceanic CO2 uptake and the marine ecosystem’s responses to climate change. The applicability of a marine biogeochemical model for prognostic simulations crucially depends on its ability to adequately describe the relevant physical, chemical, and biological processes. This is typically assessed by a calibration of the often poorly known model parameters. For three-dimensional coupled biogeochemistry-circulation models, a calibration using conventional optimization algorithms is still very time-consuming or even infeasible even on high performance computers. Such a computationally demanding calibration can now be achieved by novel time-efficient Surrogate-based Optimization (SBO) techniques. Extending and advancing our previously developed modular and flexible optimization framework, we propose to perform a calibration of two three-dimensional biogeochemical models of different structural complexity against real data of global distributions of phosphate and oxygen. The proposed interdisciplinary research at the interface of numerical optimization and marine biogeochemistry is expected to provide significant contributions to seek powerful and versatile tools for model-based investigations of marine ecosystems.

Marine Spatial Planning Game
Dr. Jörn Schmidt,  mehr lesen This project will initiate a partnership between the Future Ocean Cluster and the Earth Institute at Columbia University by collaborating on development of a novel, game-based platform that builds on prior investments of both partners. We propose to develop a computer-based interactive and interdisciplinary spatial planning game, that will combine the strengths of Kiel’s ecoOcean platform with the SMARTIC (Strategic MAnagement of Resources in TImes of Change) tool under development by the Earth Institute. Specifically, this proposal requests support to 1) adapt EcoOcean’s simulation software to depict region-specific case studies guided by the framework of the SMARTIC role playing game, and 2) to research the game’s effectiveness in helping the public and decision makers become “more aware of the need for responsible and sustainable use of the ocean …”

Lagrangian Connectivity Studies in Ocean General Circulation Models – a powerful tool in physical oceanography with a wide range of interdisciplinary applications
Dr. Arne Biastoch,  mehr lesen The Lagrangian description of flow fields is a powerful tool to investigate the oceanic circulation, and to trace movements of, e.g., biological particles. Lagrangian approaches have been widely used in observational oceanography, and more recently gained relevance in assessing ocean general circulation models (OGCMs). Although the simulation of trajectories using OGCM velocity outputs in an offline mode is well established, the analysis of up to millions of individual pathways is typically limited to qualitative descriptions and basic statistics, such as the calculation of mean transports. In addition, results may be biased due to poorly represented influence of meso- and submesoscale processes. This project aims to assess and improve Lagrangian connectivity studies, using output of a hierarchy of realistically driven OGCMs, including eddy-resolving configurations. Particular focus will be on the spreading of water masses within the Atlantic Meridional Overturning Circulation. Amounts, pathways, and timescales of deep water masses originating in the subpolar North Atlantic and arriving in the subtropics will be identified and contrasted to those of surface and intermediate water masses from sources in the Southern Hemisphere. An important component will be the testing and application of the improved methodology on examples of biological connectivity. The project will be supervised by Arne Biastoch (GEOMAR) and will be incorporated within R11 “Predicted Ocean”. It will benefit from multidisciplinary expertise through collaboration with Thorsten Reusch (GEOMAR) in R8 “Evolving Ocean”, Steffen Börm (CAU Kiel) and Bruno Blanke (LPO, Brest, France).

Employing high-resolution simulations of reactive flows through porous media to predict seafloor resources
Prof. Steffen Börm,  mehr lesen For the investigation of hydrothermal systems, fractured reservoirs and gas migration in the seafloor, accurate simulations of circulation processes through porous media are important. They allow reliable predictions and give a useful prognosis of geological hazards. It is a challenging task to develop models that represent the physical situation as well as possible on one hand. On the other hand the numerical solution of these models should be calculated within acceptable time. Especially for flows through porous and fractured media we need the possibility to solve high-resolution 3-D models, but solving 3-D models is much more memory and time consuming than 2-D models. Hence it is my goal to develop a new method for solving these problems. I propose an improved discretization technique and a Conjugate Gradient solver with geometric multi-grid preconditioning. Since the coarse grid will still be very large for complex geometries, I intend to use a hierarchical matrix method as a coarse grid solver in the multi-grid algorithm. Hierarchical matrices are particularly suitable for solving large linear systems in a storage and time efficient way. This allows us to investigate high-resolution models, particularly in fractured and complex media, like a structurally complex basalt layer or depleted oil reservoirs.

Deciphering the Lost Years, novel in‐situ/silico tracking of neonate seaturtles
Dr. Arne Biastoch,  mehr lesen The dispersal of juvenile organisms drives the life-history evolution, dynamics and habitats of many endangered marine vertebrate populations. However, the movements/behaviours of small organisms, like hatchling sea turtles, remain enigmatic. We thus propose a novel interdisciplinary campaign to utilise advances in the miniaturisation of animal tracking devices and conduct the first multi-day hatchling tracking study to gain crucial information on their movements/swimming behaviours whilst dispersing offshore. Custom-made “hatchling shaped drifters” will also be released into the ocean to acquire in-situ Lagrangian data on surface currents experienced by hatchlings and to track passive dispersal trajectories. These observations will be analysed in-silico with currents and particle drift simulated using ocean models that resolve current variability down to length scales of c.10 km.

From one‐ to three‐ dimensional thinking in global change research: Adding fluctuations to the usual static treatments may drastically change our understanding of pending environmental shifts.
Dr. Andreas Lehmann,  mehr lesen Climate change is projected to not only shift environmental means but to also increase variability around means and the intensity of extreme events. This may exert additional stress to organisms, or, in contrast, provide transient refuges from stress. We hypothesize that (i) fluctuating temperature stress will very differently affect marine organisms as compared to constant stress of the same mean intensity, and that (ii) the two additional dimensions of a stress regime, stress intensity (amplitude) and stress duration (frequency), will determine the biological impact. We will also analyse temperature time series of coastal Baltic Sea habitats with respect to shifts in any of these dimensions. By analysing on-going shifts in fluctuations in the context of sensitivities of organisms, observed from the lab experiments, we will be able to make more realistic predictions of climate change impacts on ecosystems.

Transatlantic sea‐to‐air nitrous oxide fluxes: What we can learn from isotope and eddy covariance techniques
mehr lesen We propose to use isotope and 15N site preference techniques, in conjunction with direct eddy covariance trace gas flux measurements, to better constrain the importance of the ocean as a source of nitrous oxide (N2O) to the atmosphere and quantify how various physical and biogeochemical variables regulate sea-to-air N2O fluxes.

Giving the climate community what they need: Continuous, autonomous direct measurements of carbon dioxide (CO2) air‐sea flux
Dr. Tobias Steinhoff,  mehr lesen Can eddy covariance measurements be used to directly determine open ocean CO2 flux continuously and autonomously? If yes, the key result of this work would be autonomous systems to mount onboard a fleet of voluntary observing ships (VOS) to provide continuous measurements of CO2 air-sea flux, in-situ, over unprecedented temporal/spatial scales. The impacts would be enormous, allowing the climate community to directly characterize the seasonal and interannual variations in the ocean’s uptake of anthropogenic CO2 and better predict future climate impacts.

LASSO_Lagrangian study of marine trace gas Air-Sea exchange over the Ocean
Dr. Christa Marandino,  mehr lesen Air – sea exchange processes of marine-derived trace gases at the land-coastal interface potentially impact climate, air quality, and human health. These processes need to be explored in order to close gaps in the understanding of the effect of concentration variation, emission strengths, and sources. Applying the novel technology of drones, including remote imaging, opens new dimensions of accessibility and flexibility that will address open scientific questions of air-sea exchange along coastal boundaries. We will conduct discrete air sampling with subsequent analysis of >50 trace gases across the surf zone. Concurrent imaging with the sampling will for the first time differentiate between advective and near-coastal processes, such as wave breaking, on the ambient gas concentrations.

Autonomous oceanic turtle drifters
Dr. Rebecca Scott,  mehr lesen Dispersal is a key life history trait amongst marine species. However many organisms, like hatchling sea turtles, are too small to be tracked. Here, we plan to develop novel autonomous oceanic turtle drifters that can be tracked via satellite to collect vital data on surface ocean currents and the impacts of active directional swimming on the dispersion of small organisms reliant on ocean currents for their survival and long distance dispersal. These observations will be analysed in-silico with currents and particle drift simulated using ocean models and key biological data.

The Future Ocean: A spatial audiovisual installation projecting the future of the oceans within an abstract soundscape
Dr. Nicolaas Glock,  mehr lesen Science influenced contemporary art and musical composition in many different facets, while the artistic presentation has led to new social and cultural perceptions about science[1]. Varese was inspired by processes like crystal growth, while Xenakis based his music on stochastic events. As a transdisciplinary artistic research project we propose to create an audiovisual installation based on projections about the future ocean focusing on sea level rise. Within the context of the “Wissenschaftsjahr der Ozeane 2016/17” this project acts within a good time frame for public debate. The sonic part of the installation will be based on concrete recorded sounds from the ocean and, respectively, oceanic research. These sounds will be used for asymmetric granular synthesis and other modular sound manipulations to create an abstract spatial soundscape. The whole project will be implemented in two parts: 1.: Development and presentation in the wave field synthesis laboratory at the centre for microtonal music and multimedia in Hamburg (Hochschule für Musik und Theater) and 2.: The creation of a new audio-visual installation in Kiel. Wave field synthesis can create virtual sound sources by producing wave fronts synthesized by a large number of individually controlled loud speakers. These virtual sound sources are independent from the position of the listener, e.g. a listener can walk around or through a virtual sound source. Sea level rise will be simulated by gradual filling of the room with “soundgrains” using granular synthesis, resulting in a gradual sound immersion of the recipient. Ocean acidification might be simulated by representing H3O+ ions with “soundgrains” which are stochastically distributed within the room and raise their concentration according to predicted future pH changes. Temperature changes might be represented by changes in pitch and spatial velocity of the sounds. After the realization of the project and presentation in the wave field synthesis lab the sonic part will be compiled to an installation in Kiel which will create a spatial sound field by the distribution of several loud speakers, using concrete instead of virtual sound sources. The visual part of the installation will support the soundscape and be created by the Muthesius Academy of Arts under supervision of Prof. Tom Duscher. With the use of projection mapping and sensors visual representations of the data will be projected into the special installation. While the visitor enters the installation the projection and sound will react to his movement. The presence of the visitor will interact with the environment as a metaphor of the real life relationship between men and nature. Visual elements can include maps of sea-level rise scenarios at different temporal and spatial scales photographs or movies of ice-sheet melting or graphs and maps of coastal population distribution and its responses to changing sea levels.