Satellite observations of long range transport of a large BrO plume in the Arctic

Ozone Depletion Events (ODE) during polar springtime are a well known phenomenon in the Arctic and Antarctic boundary layer. They are caused by the catalytic destruction of ozone by halogens producing reactive halogen oxides like bromine monoxide (BrO). The key halogen bromine can be rapidly transferred into the gas phase in an autocatalytic process – the so called "Bromine Explosion". However, the exact mechanism, which leads to an initial bromine release as well as the influence of transport and chemical processes on BrO, is still not clearly understood. <br><br> In this study, BrO measurements from the satellite instrument GOME-2 are used together with model calculations with the dispersion model FLEXPART to study an arctic BrO event in March 2007, which could be tracked over several days and a large area. Full BrO activation was observed within one day east of Siberia with subsequent transport to Hudson Bay. The event was linked to a cyclone with very high surface wind speeds, which could have been involved in the production and lifting of aerosols or blowing snow. Considering the short life time of BrO, transported aerosols or snow can also provide the surface for BrO recycling within the plume for several days. The evolution of the BrO plume could be reproduced by FLEXPART simulations of a passive tracer indicating that the activated air mass was transported all the way from Siberia to Hudson Bay. To localise the most probable transport height, model runs initialised in different heights have been performed showing similar transport patterns throughout the troposphere but best agreement with the measurements between the surface and 3 km. The influence of changes in tropopause height on measured BrO values has been considered, but cannot completely explain the observed high BrO values. Backward trajectories from the area of BrO initialisation show upward lifting from the surface up to 3 km and no indication for intrusion of stratospheric air. These observations are consistent with a scenario in which bromine in the air mass was activated on the surface within the cyclone, lifted upwards and transported over several thousand kilometres to Hudson Bay

Global observations of tropospheric BrO columns using GOME-2 satellite data

Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured BrO columns and estimates of the stratospheric BrO content from a climatological approach driven by O<sub>3</sub> and NO<sub>2</sub> observations. Comparisons between the GOME-2 results and BrO vertical columns derived from correlative ground-based and SCIAMACHY nadir observations, present a good level of consistency. We show that the adopted technique enables separation of stratospheric and tropospheric fractions of the measured total BrO columns and allows quantitative study of the BrO plumes in polar regions. While some satellite observed plumes of enhanced BrO can be explained by stratospheric descending air, we show that most BrO hotspots are of tropospheric origin, although they are often associated to regions with low tropopause heights as well. Elaborating on simulations using the <i>p</i>-TOMCAT tropospheric chemical transport model, this result is found to be consistent with the mechanism of bromine release through sea salt aerosols production during blowing snow events. No definitive conclusion can be drawn however on the importance of blowing snow sources in comparison to other bromine release mechanisms. Outside polar regions, evidence is provided for a global tropospheric BrO background with column of 1–3 × 10<sup>13</sup> molec cm<sup>−2</sup>, consistent with previous estimates

Das Verhalten nanostrukturierter Schaltungen unter der Berücksichtigung von Quanteneffekten [The behavior of nanostructured circuits with regard to quantum effects]

In this paper we discuss the expected impact of quantum effects in nanostructured CMOS circuits. In order to describe transport in mesoscopic electronic systems our group develops a 1-d numerical simulation packet based on the "non equilibrium Green's functions" (NEGF) formalism. By means of the obtained simulation results we develop extended SPICE circuit models. With these SPICE models the influence of quantum effects to the functionality of classical circuit concepts can be studied. Using these results it is our intention to develop circuits with a higher robustness against these quantum effects. For the illustration of our simulation concept we discuss some results of some circuit examples.Aufgrund der Bedeutung der MOS-Technologie für Halbleiterindustrie und deren fortschreitende Miniaturisierung ist es wichtig sicherzustellen, dass die klassischen Schaltungskonzepte für stark skalierte Bauelemente nicht ihre Gültigkeit verlieren. Ziel unserer Arbeitsgruppe ist es ein Simulatorpaket zu entwickeln, welches von einer physikalischen Sicht heraus quantenmechanische Einflüsse in integrierten Schaltungen ermittelt und Konsequenzen für zukünftiges Schaltungsdesign prognostiziert. Zur Berechnung und Modellierung der Quanteneffekte wird ein auf dem "non equilibrium Green's functions" (NEGF) Formalismus basierender numerischer 1-dimensionaler Simulator entwickelt. Auf der Basis von numerischen Transportsimulationen werden Ersatzschaltbilder für die SPICE Simulationsumgebung erstellt, um den Einfluss der Quanteneffekte in die Schaltungssimulation einzubinden

Das Verhalten nanostrukturierter Schaltungen unter der Berücksichtigung von Quanteneffekten

Aufgrund der Bedeutung der MOS-Technologie für Halbleiterindustrie und deren fortschreitende Miniaturisierung ist es wichtig sicherzustellen, dass die klassischen Schaltungskonzepte für stark skalierte Bauelemente nicht ihre Gültigkeit verlieren. Ziel unserer Arbeitsgruppe ist es ein Simulatorpaket zu entwickeln, welches von einer physikalischen Sicht heraus quantenmechanische Einflüsse in integrierten Schaltungen ermittelt und Konsequenzen für zukünftiges Schaltungsdesign prognostiziert. Zur Berechnung und Modellierung der Quanteneffekte wird ein auf dem &quot;non equilibrium Green&apos;s functions&quot; (NEGF) Formalismus basierender numerischer 1-dimensionaler Simulator entwickelt. Auf der Basis von numerischen Transportsimulationen werden Ersatzschaltbilder für die SPICE Simulationsumgebung erstellt, um den Einfluss der Quanteneffekte in die Schaltungssimulation einzubinden. <P> In this paper we discuss the expected impact of quantum effects in nanostructured CMOS circuits. In order to describe transport in mesoscopic electronic systems our group develops a 1-d numerical simulation packet based on the &quot;non equilibrium Green&apos;s functions&quot; (NEGF) formalism. By means of the obtained simulation results we develop extended SPICE circuit models. With these SPICE models the influence of quantum effects to the functionality of classical circuit concepts can be studied. Using these results it is our intention to develop circuits with a higher robustness against these quantum effects. For the illustration of our simulation concept we discuss some results of some circuit examples

Characterization of new sulfur and selenium-based glasses containing lead iodine.

International audienc

Simultaneous satellite observations of IO and BrO over Antarctica

This article reports on satellite observations of iodine monoxide (IO) and bromine monoxide (BrO). The region of interest is Antarctica in the time between spring and autumn. Both molecules, IO and BrO, are reactive halogen species and strongly influence tropospheric composition. As a result, a better understanding of their spatial distribution and temporal evolution is necessary to assess accurately their role in tropospheric chemistry. Especially in the case of IO, information on its present magnitude, spatial distribution patterns and source regions is still sparse. <br><br> The present study is based on six years of SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY) data recorded in nadir viewing geometry. Multi-year averages of monthly mean IO columns are presented and compared to the distributions of BrO. Influences of the IO air mass factor and the IO absorption cross section temperature dependence on the absolute vertical columns are discussed. The long-term observations of IO and BrO columns yield new insight into the temporal and spatial variation of IO above the Antarctic region. The occurrence of IO on Antarctic sea ice in late spring (November) is discovered and presented. In addition, the comparison between IO and BrO distributions show many differences, which argues for different mechanisms and individual nature of the release of the two halogen oxide precursors. The state of the ecosystem, in particular the changing condition of the sea ice in late spring, is used to explain the observations of the IO behaviour over Antarctica and the differences between IO and BrO distributions

Erratum: Simultaneous satellite observations of IO and BrO over Antarctica (Atmospheric Chemistry and Physics (2012) 12 (6565-6580))

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