445 research outputs found
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
Comparison of the O3 chemistry in the Po Valley with that in the Benelux region as simulated with MECO(n)
No full textNon-traffic (i.e. households, industry, etc.) emissions and land transport emissions are important anthropogenic precursors of tropospheric O3 and affect the air quality and contribute to global climate change. In order to improve air quality and mitigate climate change, robust knowledge of the amount of O3 formed by different emission sources is required. This study investigates the contributions of the different emission sectors to the ground-level ozone budget in Europe and Southeast Asia. For the present study we applied the MECO(n) model system, which couples the global chemistry-climate model EMAC on-line with the regional chemistry-climate model COSMO-CLM/MESSy. We used MECO(n) with a source apportionment method for ozone to investigate regional differences of the contributions from different emissions to ground-level ozone. Our findings show that contributions from anthropogenic non-traffic emissions to ground-level ozone are larger in Southeast Asia than in Europe. The contrary applies for the land transport emissions, which are more important in Europe compared to Southeast Asia
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
A trans-splicing group I intron and tRNA-hyperediting in the mitochondrial genome of the lycophyte Isoetes engelmannii
No full textGrewe F, Viehöver P, Weisshaar B, Knoop V. A trans-splicing group I intron and tRNA-hyperediting in the mitochondrial genome of the lycophyte Isoetes engelmannii. Nucleic Acids Research. 2009;37(15):5093-5104
Eco-efficiency in aviation
No full textAir traffic guarantees mobility and serves the needs of society to travel over long distances in a decent time. But aviation also contributes to climate change. Here, we present various mitigation options, based on technological and operational measures and present a framework to compare the different mitigation options by taking into account aspects, such as changes in operational costs, climate impact reduction, eco-efficiency, possible starting point of the mitigation option and the investment costs. We show that it is not possible to directly rank these options because of the different requirements and framework conditions. Instead, we introduce two different presentations that take into account these different aspects and serve as a framework for intercomparison
Trends in ozone concentration caused by emissions from fossil fuel combustion and natural sources
No full textjohannespletzer/rf-of-hypersonic-trajectories: First public release v1.0-doi
No full text<p><strong><span>Radiative forcing of hypersonic aircraft emission inventories</span></strong></p>
<p><strong><span></span></strong><span>The software quantifies climate impact of hypersonic aircraft emission inventories as a number and within seconds instead of very long numerical simulations that produce Petabytes of data. The input requires water vapor, hydrogen and nitrogen oxide emission data along flight trajectories.</span></p>
<p><span>The repository provides a Python package, examples and an executable to calculate the climate impact (stratosphere adjusted radiative forcing) of hypersonic aircraft emission inventories. The radiative forcing of water vapour changes and ozone changes are calculated on the basis of water vapour, hydrogen and nitrogen oxide emissions. <br></span></p>
<p><strong><span>Limitations</span></strong></p>
<p><span>Interpolation (30-38 km) and extrapolation surface-30 km are used. It is recommended to note the following:</span></p>
<ul>
<li><span>The atmospheric and radiative sensitivites are based on results from [Pletzer et al (2024)](https://acp.copernicus.org/articles/24/1743/2024/). The atmospheric composition of the numerical climate model is based on surface emission inventories for 2050. </span></li>
<li><span>The class includes a function (`drop_vertical_levels()`) that drops emission in the troposphere or below specified altitude levels and excludes it from the climate calculation. Its use is strongly recommended as long as sensitivities are not yet extended to altitudes below 30 km.</span></li>
<li><span>The climate impact of emission inventories where the average flight altitude does not correspond to the typical hypersonic flight altitudes (about 24-40 km) should not be estimated.</span></li>
<li><span>Meaningful results can be expected for the radiative effect of water vapour changes due to water vapour emissions. This explicitly excludes the radiative effect of water vapour changes due to hydrogen and nitrogen oxide emissions.</span></li>
<li><span>Meaningful results can be expected for the radiative effect of ozone changes due to water vapour, hydrogen and nitrogen oxide emissions.</span></li>
</ul>
<p><span>Please keep these limitations in mind when using the software.</span></p>
<p><strong><span>Python environment requirements</span></strong></p>
<p><span>The software requires various functions from the following python modules:</span></p>
<ul>
<li><span>numpy</span></li>
<li><span>pandas</span></li>
<li><span>xarray</span></li>
<li><span>scipy</span></li>
<li><span>xlsxwriter</span></li>
<li><span>netcdf4</span></li>
<li><span>aerocalc3</span></li>
</ul>
<p><span> </span><span>Install the required packages with <code>pip install numpy pandas xarray scipy xlsxwriter netcdf4 aerocalc3</code></span></p>
<p><strong><span>Getting started</span></strong></p>
<p><span>The repo contains two example notebooks for processing of emission inventories in mat- and nc-format. Otherwise, the user can run the main.py executable which reads all emission inventory files within the folder and returns the calculated radiative forcing in an xlsx file. Execute main.py with `python3 main.py <path_to_your_emission_files>`. Please contact Johannes Pletzer for any questions.</span></p>
<p><strong><span>Code quality</span></strong></p>
<p><span>The code was formatted according to PEP 8 style with the help of the modules 'flake8', 'isort', 'pylint' and 'black'.</span></p>
Finding the climate optimal cruise altitude for a selection of aircraft types and mission combinations
No full textThe climate impact of aviation is assessed as function of the emission altitude for two different aircraft types, the Boeing 787-800 and Boeing 777-300ER. The basis for this research is an assembly of 2,738 historical trajectories for which the fuel consumption and emissions were determined by using Piano-X aircraft performance data and atmospheric weather data from the European Centre for Medium-Range Weather Forecasts. The resulting emissions served as input for the climate response model AirClim which calculated the resulting climate response over time. To analyze the effect of changes in cruise altitude, the fuel consumption and corresponding emissions were recalculated for scenarios with relocated cruise altitude profiles ranging from an upward shift of 2000 ft to a downward shift of 18000 ft with respect to the original cruise altitude. By shifting cruise altitudes down, the total climate impact was found to be reduced for both aircraft types where the minimal climate impact is found for the lowest analyzed cruise altitude. The reduction in climate impact is mainly the result of the reduced short term forcings from contrail cirrus, ozone and the induced destruction of methane where their individual contribution to the total climate impact reduction was found to be dependent on aircraft type. Relocating cruise altitudes up was found to increase the climate impact for both aircraft types.Aerospace Engineerin
- …
