The response of drifting buoys to currents and wind

Two buoy types have been tested with respect to their drift performance under drogued and undrogued conditions. Additionally, forces acting on the buoys were measured directly. Quadratic drag laws have been confirmed for the drag in water and the combined drag of wind and waves. Stokes drift contributes about one half to the wind factor of 0.023, which is obtained for undrogued buoys in the Atlantic. The forces on a windowshade drogue are given by a linear relation between force and water velocity for speeds exceeding 10 cm/s. They have been extrapolated to speeds of less than 10 cm/s by both a linear and a quadratic relationship. Correlations between drift and wind speed in the Atlantic suggest that the linear law is a better approximation under realistic conditions. According to these measurements in the Atlantic the described buoy-drogue system with a windowshade drogue in 100-m depth is a good current-measuring device. Slippage is negligible for wind speeds of less than 15 m/s and is less than 2 cm/s under gale conditions. Undrogued buoys are strongly affected by wind and cannot be used for the analysis of currents without correction, even under light winds

Communicating Science to High School Pupils by Video Production: Lessons Learned

The Collaborative Research Centre 754 (SFB 754) at GEOMAR in Kiel, Germany is an interdisciplinary research programme, which investigates the threats posed by ocean de-oxygenation and how this is coupled with climate change and the nutrient balance in the tropical oceans. The outreach component of SFB 754 has the task of producing videos with and for school pupils, in which different aspects of the science of the SFB are explained and introduced in a short and entertaining fashion. The goal is to attract pupils to sciences, both by the active involvement in the video production and by the consumption of the videos made by other pupils. So far more than 30 video clips were published on a dedicated website for viewing and download. The process of video production is enjoyable for all parties involved, but it is also time consuming and entails considerably more work for students and teachers, than normal lessons in class. As a result, the project now concentrates on dedicated summer schools and after-school activities as a platform for video productio

Differences in drift behavior between drogued and undrogued satellite-tracked drifting buoys

Drift behavior of drogued and undrogued Hermes‐type buoys is studied. After drogue loss, an increase in drift speed and acceleration is observed as well as improved correlations between drift and wind in both speed and direction. With these criteria, a method for the separation of large data sets into a drogued and an undrogued part has been developed. In most areas of the North Atlantic this works very well; problems arise in regions with strong surface currents and/or light winds. A statistical analysis is performed in a selected area to demonstrate the errors that can be caused by indiscriminate use of drogued and undrogued drifters. Mean and rms velocities as well as kinetic energies change significantly when undrogued buoys are considered. Therefore caution is essential when using surface drifters without drogues

Eddy-Permitting Ocean Circulation Hindcasts of Past Decades

International audienc

TOMÁS DE AQUINO, Comentarios al libro de Aristóteles sobre la interpretación, traducción e introducción de Mirko Skarica; estudio preliminar y notas de Juan Cruz Cruz, Colección de Pensamiento Medieval y Renacentista, n. 5, EUNSA, Pamplona 1999, LI + 202 pp., 16 x 23, ISBN 84-313-1699-3. [RECENSIÓN]

Wissenschaftskommunikation für Jugendliche durch Jugendliche: Geht das überhaupt? Können komplexe Inhalte von ganzen Forschungsschwerpunkten durch Schülerinnen und Schüler erfasst, aufbereitet und an andere Schüler weiter vermittelt werden