840 research outputs found
Variability of blowfly head optomotor responses
No full textRosner R, Egelhaaf M, Grewe J, Warzecha A-K. Variability of blowfly head optomotor responses. Journal of Experimental Biology. 2009;212(8):1170-1184
Impact of climate variability on tropospheric ozone
No full textA simulation with the climate–chemistry model (CCM) E39/C is presented, which covers both the troposphere and stratosphere
dynamics and chemistry during the period 1960 to 1999. Although the CCM, by its nature, is not exactly representing observed
day-by-day meteorology, there is an overall model's tendency to correctly reproduce the variability pattern due to an inclusion of
realistic external forcings, like observed sea surface temperatures (e.g. El Niño), major volcanic eruption, solar cycle,
concentrations of greenhouse gases, and Quasi-Biennial Oscillation. Additionally, climate–chemistry interactions are included, like
the impact of ozone, methane, and other species on radiation and dynamics, and the impact of dynamics on emissions (lightning).
However, a number of important feedbacks are not yet included (e.g. feedbacks related to biogenic emissions and emissions due to
biomass burning). The results show a good representation of the evolution of the stratospheric ozone layer, including the ozone
hole, which plays an important role for the simulation of natural variability of tropospheric ozone. Anthropogenic NOx emissions
are included with a step-wise linear trend for each sector, but no interannual variability is included. The application of a number of
diagnostics (e.g. marked ozone tracers) allows the separation of the impact of various processes/emissions on tropospheric ozone
and shows that the simulated Northern Hemisphere tropospheric ozone budget is not only dominated by nitrogen oxide emissions
and other ozone pre-cursors, but also by changes of the stratospheric ozone budget and its flux into the troposphere, which tends to
reduce the simulated positive trend in tropospheric ozone due to emissions from industry and traffic during the late 80s and early
90s. For tropical regions the variability in ozone is dominated by variability in lightning (related to ENSO) and stratosphere–
troposphere exchange (related to Northern Hemisphere Stratospheric dynamics and solar activity). Since tropospheric background
chemistry is regarded only, the results are quantitatively limited with respect to derived trends. However, the main results are
regarded to be robust.
Although the horizontal resolution is rather coarse in comparison to regional models, such kind of simulations provide useful
and necessary information on the impact of large-scale processes and inter-annual/decadal variations on regional air quality
Marco Ferreri: Dillinger è morto/Dillinger ist tot (1969)
No full textMarco Ferreri con il suo film Dillinger è morto sembra radiografare la crisi italiana del post Boom economico. In un momento in cui la rivoluzione studentesca potrebbe aprire l’orizzonte a nuove utopie, la borghesia italiana appare stanca e totalmente immersa in un benessere piatto e routinario. La crisi rappresentata da Ferreri è anche quella di un individuo sempre più interprete di una “società dello spettacolo” che divora la dimensione intima e privata, decostruendo istituzioni e valori. I colori saturi, il design avveniristico, il finale tragico venato di ironia: sono tutti elementi analizzati nell’articolo che prova ad inserire il film del regista italiano nel clima internazionale dei profondi mutamenti sociali e culturali del periodo
Book Review of Words on Water: Literary and Cultural Representations by Maureen Devine and Christa Grewe-Volpp (eds.)
No full textBook Review of Words on Water: Literary and Cultural Representations by Maureen Devine and Christa Grewe-Volpp (eds.
Comparison between global models and measurements of trace gases during TROCCINOX
No full textAirborne trace gas measurements carried out over southern Brazil during TROCCINOX-1 with the Falcon aircraft are compared to results from three global models: ECHAM, MATCH and TM4. The agreement between the models, with different parameterizations for lightning-produced NOX (=NO+NO2), and the measurements is investigated along single flight tracks. A new parameterization based on the mass flux in the updrafts [Grewe et al., 2001; Kurz and Grewe, 2002] shows promising results in comparison to the more commonly used parameterization based on the cloud top height [Price and Rind, 1992]. The most realistic model results for the total amount of lightning-produced NOX on the global scale were achieved with 5 Tg(N) yr-1
Hoffmann, Geo. W. (Death, 1879-12-18)
No full textAddress: W. Liberty St.Age at death: 3moPg 121/1879/202/M W S/City/Dr. L. Grewe/J Fuldner/Spring GroveOriginal record filed in drawer labeled 'HOFFMANN-HOLMES'
Simulation of Stratospheric Water Vapor Trends: Impact on Stratospheric Ozone Chemistry
No full textA transient model simulation of the 40-year time
period 1960 to 1999 with the coupled climate-chemistry
model (CCM) ECHAM4.L39(DLR)/CHEM shows a stratospheric
water vapor increase over the last two decades of
0.7 ppmv and, additionally, a short-term increase after major
volcanic eruptions. Furthermore, a long-term decrease in
global total ozone as well as a short-term ozone decline in the
tropics after volcanic eruptions are modeled. In order to understand
the resulting effects of the water vapor changes on
lower stratospheric ozone chemistry, different perturbation
simulations were performed with the CCM ECHAM4.L39-
(DLR)/CHEM feeding the water vapor perturbations only to
the chemistry part. Two different long-term perturbations of
lower stratospheric water vapor, +1 ppmv and +5 ppmv, and a
short-term perturbation of +2 ppmv with an e-folding time of
two months were applied. An additional stratospheric water
vapor amount of 1 ppmv results in a 5–10% OH increase in
the tropical lower stratosphere between 100 and 30 hPa. As
a direct consequence of the OH increase the ozone destruction
by the HOx cycle becomes 6.4% more effective. Coupling
processes between the HOx-family and the NOx/ClOxfamily
also affect the ozone destruction by other catalytic
reaction cycles. The NOx cycle becomes 1.6% less effective,
whereas the effectiveness of the ClOx cycle is again
slightly enhanced. A long-term water vapor increase does
not only affect gas-phase chemistry, but also heterogeneous
ozone chemistry in polar regions. The model results indicate
an enhanced heterogeneous ozone depletion during antarctic
spring due to a longer PSC existence period. In contrast,
PSC formation in the northern hemisphere polar vortex and
therefore heterogeneous ozone depletion during arctic spring
are not affected by the water vapor increase, because of the
less PSC activity. Finally, this study shows that 10% of the
global total ozone decline in the transient model run can
be explained by the modeled water vapor increase, but the
simulated tropical ozone decrease after volcanic eruptions is
caused dynamically rather than chemically
Climate Impact of a Potential Supersonic Fleet
No full textWithin the EU-project SCENIC the impact of a potential
supersonic fleet has been investigated. The methodology
how to estimate its climate impact is presented. A number
of sensitivity studies are analysed to identify options to
minimise climate impact. Since stratospheric water vapour
emissions are the most important contributor to climate
change induced by supersonics those scenarios are
minimising the climate impact which have the lowest cruise
altitude.
In order to include climate aspects in multi-disciplinary
optimisation for supersonics an assessment tool (AirClim)
has been developed within the EU Integrated Project
HISAC, which is briefly presented. The main atmospheric
input data describe the atmosphere’s sensitivity to the
emission region. Based hereon a functional relationship
has been developed between basic (supersonic) aircraft
design parameters (cruise altitude, fuel consumption) and
climate change
AMYGDALA AND CORTICAL GAMMA-BAND RESPONSES TO EMOTIONAL FACES DEPEND ON THE ATTENDED TO VALENCE
No full textWeidner E, Moratti S, Schindler S, Grewe P, Bien C, Kißler J. AMYGDALA AND CORTICAL GAMMA-BAND RESPONSES TO EMOTIONAL FACES DEPEND ON THE ATTENDED TO VALENCE. Psychophysiology . 2023;60(Suppl. 1):S158
Outdoor performance of a motion-sensitive neuron in the blowfly
No full textEgelhaaf M, Grewe J, Kern R, Warzecha A-K. Outdoor performance of a motion-sensitive neuron in the blowfly. Vision research. 2001;41(27):3627-3637.We studied an identified motion-sensitive neuron of the blowfly under outdoor conditions. The neuron was stimulated by oscillating the fly in a rural environment. We analysed whether the motion-induced neuronal activity is affected by brightness changes ranging between bright sunlight and dusk, In addition, the relationship between spike rate and ambient temperature was determined. The main results are: (1) The mean spike rate elicited by visual motion is largely independent of brightness changes over several orders of magnitude as they occur as a consequence of positional changes of the sun. Even during dusk the neuron responds strongly and directionally selective to motion. (2) The neuronal spike rate is not significantly affected by short-term brightness changes caused by clouds temporarily occluding the sun. (3) In contrast, the neuronal activity is much affected by changes in ambient temperature. (C) 2001 Elsevier Science Ltd. All rights reserved
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