Mediterranean cyclones and windstorms in a changing climate

Changes in the frequency and intensity of cyclones and associated windstorms affecting the Medi-terranean region simulated under enhanced Greenhouse Gas forcing conditions are investigated. The analysis is based on 7 climate model integrations performed with two coupled global models (ECHAM5 MPIOM and INGV CMCC), comparing the end of the twentieth century and at least the first half of the twenty-first century. As one of the models has a considerably enhanced resolution of the atmosphere and the ocean, it is also investigated whether the climate change signals are influenced by the model resolution. While the higher resolved simulation is closer to reanalysis climatology, both in terms of cyclones and windstorm distributions, there is no evidence for an influence of the resolution on the sign of the climate change signal. All model simulations show a reduction in the total number of cyclones crossing the Mediterranean region under climate change conditions. Exceptions are Morocco and the Levant region, where the models predict an increase in the number of cyclones. The reduction is especially strong for intense cyclones in terms of their Laplacian of pressure. The influence of the simulated positive shift in the NAO Index on the cyclone decrease is restricted to the Western Mediterranean region, where it explains 10–50 % of the simulated trend, depending on the individual simulation. With respect to windstorms, decreases are simulated over most of the Mediterranean basin. This overall reduction is due to a decrease in the number of events associated with local cyclones, while the number of events associated with cyclones outside of the Mediterranean region slightly increases. These systems are, however, less intense in terms of their integrated severity over the Mediterranean area, as they mostly affect the fringes of the region. In spite of the general reduction in total numbers, several cyclones and windstorms of intensity unknown under current climate conditions are identified for the scenario simulations. For these events, no common trend exists in the individual simulations. Thus, they may rather be attributed to long-term (e.g. decadal) variability than to the Greenhouse Gas forcing. Nevertheless, the result indicates that high-impact weather systems will remain an important risk in the Mediterranean Basin

10 Jahre nach dem Mauerfall – Vom Alltag des innerdeutschen Ost-West-Konflikts

Textdokumentation zur Veranstaltung der Osnabrücker Friedensgespräche am 3. März 199

IEEE INTERNET COMPUTING 1089-7801/04/$20.00 2004 IEEE Published by the IEEE Computer Society JANUARY . FEBRUARY 2004 55 Editor: Siobhn Clarke . [email protected]

twork. This mode is available even if there are no base stations within the nodes' range. The advantage of these so-called mobile ad hoc wireless networks (Manets) is that, because they don't need an infrastructure, they are quickly deployable and highly flexible. Hence, Manets can extend the Internet beyond its traditional scope to new, previously inaccessible areas, making Web services available "anytime, anywhere." This will enable novel applications that will combine with existing software and infrastructure, and exploit available Internet knowledge. Enhanced automobile routing based on current traffic conditions, for example, could be deployed in cars based on the temporary formation of ondemand networks (for a good example of an existing mobility management solution on the Internet, see www.vmzberlin.de). However, despite the Manet research community 's rapid progress in recent years, fundamental Mobile ad hoc wireless networks will extend the Internet into new territory, makin

802.11 Link Quality and its Prediction - An Experimental Study

Abstract. Reliable link quality prediction is an imperative for the efficient operation of mobile ad-hoc wireless networks (MANETs). In this paper it is shown that popular link quality prediction algorithms for 802.11 MANETs perform much more poorly when applied in real urban environments than they do in corresponding simulations. Our measurements show that the best performing prediction algorithm failed to predict between 18 and 54 percent of the total observed packet loss in the real urban environments examined. Moreover, with this algorithm between 12 and 43 percent of transmitted packets were lost due to the erroneous prediction of link failure. This contrasts sharply with near-perfect accuracy in corresponding simulations. To account for this discrepancy we perform an in-depth examination of the factors that influence link quality. We conclude that shadowing is an especially significant and hitherto underestimated factor in link quality prediction in MANETs.

SwissFEL: The Swiss X-ray Free Electron Laser

The SwissFEL X-ray Free Electron Laser (XFEL) facility started construction at the Paul Scherrer Institute (Villigen, Switzerland) in 2013 and will be ready to accept its first users in 2018 on the Aramis hard X-ray branch. In the following sections we will summarize the various aspects of the project, including the design of the soft and hard X-ray branches of the accelerator, the results of SwissFEL performance simulations, details of the photon beamlines and experimental stations, and our first commissioning results