ALBERT

Description: Widespread flooding in June 2013 caused damage costs of €6 to 8 billion in Germany, and awoke many memories of the floods in August 2002, which resulted in total damage of €11.6 billion and hence was the most expensive natural hazard event in Germany up to now. The event of 2002 does, however, also mark a reorientation toward an integrated flood risk management system in Germany. Therefore, the flood of 2013 offered the opportunity to review how the measures that politics, administration, and civil society have implemented since 2002 helped to cope with the flood and what still needs to be done to achieve effective and more integrated flood risk management. The review highlights considerable improvements on many levels, in particular (1) an increased consideration of flood hazards in spatial planning and urban development, (2) comprehensive property-level mitigation and preparedness measures, (3) more effective flood warnings and improved coordination of disaster response, and (4) a more targeted maintenance of flood defense systems. In 2013, this led to more effective flood management and to a reduction of damage. Nevertheless, important aspects remain unclear and need to be clarified. This particularly holds for balanced and coordinated strategies for reducing and overcoming the impacts of flooding in large catchments, cross-border and interdisciplinary cooperation, the role of the general public in the different phases of flood risk management, as well as a transparent risk transfer system. Recurring flood events reveal that flood risk management is a continuous task. Hence, risk drivers, such as climate change, land-use changes, economic developments, or demographic change and the resultant risks must be investigated at regular intervals, and risk reduction strategies and processes must be reassessed as well as adapted and implemented in a dialogue with all stakeholders.

Description: The physics of magnetospheric boundaries is a main driver for the transport of mass, and magnetic flux at these boundaries. These processes strongly determine mass content, and magnetic flux circulation of magnetospheres. Early magnetospheric exploration had a strong focus on magnetic reconnection at the magnetopause. However better observations made increasingly clear that the Kelvin-Helmholtz (KH) instability may also represent an important process. Specifically, KH modes attracted increasing attention because simulation demonstrated that these modes presented a highly effective mechanism to transport mass into magnetospheres. While the KH mode is by nature an ideal instability and not expected to transport mass across magnetic flux tubes, it turned out that highly twisted flux tubes in the nonlinear stage can actually undergo magnetic reconnection. This process can be realized locally inside a simple vortex or at the boundaries of a twisted magnetic flux tube like a candy wrapper that is twisted too tight. Particularly for northward interplanetary field this is the most promising mechanism for mass transport into the Earth's magnetosphere because reconnection cannot operated for small magnetic shear at the boundary. In addition to these magnetofluid effects, KH vortices lead to strong increase of the surface of the magnetopause boundary thereby increasing diffusion of material across the boundary. This interaction has been examined also by many kinetic models adding to our understanding of the intrinsic processes associated with KH modes. In the past decade many of the predictions from models and simulation have been confirmed by sophisticated multi spacecraft observations.

Description: Bow shock transients such as Hot Flow Anomalies in the region upstream of the bow shock can have a major impact on the magnetosheath, can move the magnetopause by several Earth radii and can strongly influence the magnetosphere. Several of these transients are characterized by a strongly heated plasma, a major deflection of the solar wind (in extreme cases showing sunward flow), and typical properties such as frequently leading and/or trailing edge shocks. In addition they can exhibit strong flow perturbations both inside and at the boundary of events. They are also associated with major perturbations of the adjacent magnetosheath properties which include superfast jets, strong current sheets and large dynamic and static pressure perturbations. There are various kinetic models for different types of transients. This presentation is based on magnetofluid (MHD) plasma description and will consider effects of the bow shock interaction caused by the presence of an isolated magnetic flux tube with a depleted dynamic pressure. We will examine the structure and physics of the transients using two-dimensional MHD simulations and an analytic model. The results illustrate that the physics of this shock interaction is surprisingly simple and can explain many of the typical properties of HFA-like structures. Natural by-products of the interaction are boundaries that represent quasi perpendicular shocks, strong flow perturbations and jets, and interior regions with strongly decelerated flows and heated plasma.