Search

Assessing the security status of maritime infrastructures is a key factor for maritime safety and security. Facilities such as ports and harbors are highly active traffic zones with many different agents and infrastructures present, like containers, trucks or vessels. Conveying security-related information in a concise and easily understandable format can support the decision-making process of stakeholders, such as port authorities, law enforcement agencies and emergency services. In this work, we propose a novel real-time 3D reconstruction framework for enhancing maritime situational awareness pictures by joining temporal 2D video data into a single consistent display. We introduce and verify a pipeline prototype for dynamic 3D reconstruction of maritime objects using a static observer and stereoscopic cameras on an GPU-accelerated embedded device. A simulated dataset of a harbor basin was created and used for real-time processing. Usage of a simulated setup allowed verification against synthetic ground-truth data. The presented pipeline runs entirely on a remote, low-power embedded system with ∼ 6 Hz. A Nvidia Jetson Xavier AGX module was used, featuring 512 CUDA-cores, 16 GB memory and an ARMv8 64-bit octa-core CPU. [ABSTRACT FROM AUTHOR]

High‐resolution optical camera systems are opening new opportunities to study fractures in ice. Here, we present data obtained from the Modular Aerial Camera System camera system operated onboard of Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) polar aircraft in northeast Greenland in 2022. In addition, we are using optical and radar satellite imagery. The study area is the 79°N Glacier (Nioghalvfjerdsbræ, 79NG), an outlet glacier of the Northeast Greenland Ice Stream. We found that crack tips are exhibiting additional isolated cracks ahead of the main crack. Subsequent crack propagation is starting from those isolated cracks, leading to an advance of the crack, with bridges between crack faces. The bridges provide information of the episodic crack propagation. Fractures have typically a length scale of kilometers and the distance of crack faces is in the order of meters to tenths of meters. Fracture modes will be inferred from stress fields computed by an inverse modeling approach using the Ice Sheet and Sea Level System Model. To this end, a surface velocity field derived from satellite remote sensing is used for the optimal control method that constrains model parameters, for example, basal friction coefficient or rheology. [ABSTRACT FROM AUTHOR]

The largest floating tongue of Greenland's ice sheet, Nioghalvfjerdsbræ, has been relatively stable with respect to areal retreat until 2022. Draining more than 6 % of the ice sheet, a disintegration of Nioghalvfjerdsbræ's floating tongue and subsequent acceleration due to loss in buttressing are likely to lead to sea level rise. Therefore, the stability of the floating tongue is a focus of this study. We employed a suite of observational methods to detect recent changes at the calving front. We found that the calving style has changed since 2016 at the southern part of the eastern calving front, from tongue-type calving to a crack evolution initiated at frontal ice rises reaching 5–7 km and progressing further upstream compared to 2010. The calving front area is further weakened by an area upstream of the main calving front that consists of open water and an ice mélange that has substantially expanded, leading to the formation of a narrow ice bridge. These geometric and mechanical changes may be a precursor of instability of the floating tongue. We complement our study by numerical ice flow simulations to estimate the impact of future ice-front retreat and complete ice shelf disintegration on the discharge of grounded ice. These idealized scenarios reveal that a loss of the south-eastern area of the ice shelf would lead to a 0.2 % increase in ice discharge at the grounding line, while a sudden collapse of the frontal area (46 % of the floating tongue area) will enhance the ice discharge by 5.1 % due to loss in buttressing. Eventually, a full collapse of the floating tongue increases the grounding line flux by 166 %. [ABSTRACT FROM AUTHOR]