How to cite: Klenner, J., Lund, M. T., Muri, H., and Strømman, A. H.: Emission location shape atmospheric and climate effects of alternative fuels in domestic aviation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10038, https://doi.org/10.5194/egusphere-egu24-10038, 2024.

Hydrogen-powered aircraft have the potential to reduce CO2 emissions to zero. However, a significant portion of the global warming attributed to aviation arises from non-CO2 effects, including contrails. The thermodynamic state and microphysical pathways that form these contrails differ substantially between hydrogen and conventional kerosene combustion. Therefore, the overall climate impact of contrails formed by hydrogen combustion is not yet known and needs to be assessed by Global Circulation Models (GCMs). The contrail parametrization in a GCM cannot resolve the contrail formation processes. However, these early processes have a large influence on the contrail life cycle and should therefore be included in the contrail initialization of a GCM. Here, a crucial ingredient is the number of ice crystals formed during the jet phase.

In this study, we present a parametrization that provides a link between the outcome of a high-resolution model and the contrail initialization in a GCM. For that, we performed contrail formation simulations with the particle-based Lagrangian Cloud Module (LCM) in a box model approach. We assume that contrail droplets and ice crystals form solely on entrained ambient aerosols. With our simulation setup, we aim to cover the entire parameter space relevant for contrail formation in the case of hydrogen combustion. This involves varying background meteorological conditions, ambient aerosol properties, and engine exit conditions, resulting in more than 20,000 simulations.

The simulation results show that the number of formed ice crystals is mostly sensitive to a variation of the ambient aerosol background concentration, followed by a variation of the ambient temperature. We identify a parameter subspace where the number of ice crystals becomes almost independent of the size and chemical composition of the ambient aerosols.

Furthermore, we performed simulations with two coexisting background aerosol ensembles differing in mean size and/or solubility. The simulation results show that coarse mode particles have neither a direct nor an indirect influence on the number of formed ice crystals if their number concentration is 2-3 orders of magnitude lower than that of a coexisting Aitken/accumulation mode. Furthermore, the ice crystal number from simulations with the two coexisting background aerosol ensembles can be reconstructed by a weighted mean of two single simulations, each containing only one of the two aerosol ensembles. This allows to construct a simpler parametrization still covering the case of two coexisting aerosol ensembles.

We used the simulation results to train a shallow feed-forward neural network that maps the box model input parameters to the number of formed ice crystals. This neural network serves as a fit function of our simulation results, which can be implemented in a GCM for contrail initialization.

This work contributes to the collaborative effort of the German Aerospace Center (DLR) and Airbus in assessing the climate impact of H2 contrails.

How to cite: Zink, J. and Unterstrasser, S.: Parametrizing the number of formed ice crystals in contrails from hydrogen combustion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16192, https://doi.org/10.5194/egusphere-egu24-16192, 2024.

The effort to make aviation more climate-friendly requires to develop new propulsion technologies in comparison to the conventional kerosene combustion engines. Hydrogen (H₂) combustion is seen as a promising, green alternative. Assessing the climate impact of contrails, which is a major contribution to the aviation’s non-C02 effects, is an essential part of developing climate-friendly aviation. Our study investigates the properties of contrails behind H₂-powered aircraft, in particular in comparison to conventional contrails from kerosene combustion. For this, high-resolution simulations of individual contrails over their full lifecycle are performed employing the established EULAG-LCM model (a large-eddy simulation (LES) model with fully coupled particle-based ice microphysics). Young contrails and their interaction with the wake vortices are simulated as well as their transition into contrail-cirrus over time periods of several hours.

Recent simulations of contrail formation behind engines with H₂ combustion have shown that the number of created ice crystals is smaller than in conventional contrails, as the exhaust plumes are expected to be void of soot particles, on which contrail ice crystals typically form.
Previous simulations of the early contrail evolution during the vortex phase and the contrail-cirrus evolution have been performed for a broad parameter space regarding variations in meteorological and aircraft-related quantities. However, these simulations were restricted to contrails from conventional kerosene combustion.

In order to investigate the influence of a H­₂ propulsion system on the contrail evolution, two input parameters are adapted: The amount of emitted water vapour is larger and the number of initial ice crystals is smaller.  Moreover, we extend our set of atmospheric scenarios to higher ambient temperatures, as H₂ contrails can form in warmer environments where ice crystal formation in kerosene plumes does not occur.

We explore the H₂ contrail evolution for different idealised atmospheric scenarios. It is well-known that young contrails are strongly affected by the trailing wake vortices and a substantial fraction of the initially formed ice crystals can get lost due to adiabatic heating in the descending vortex pair. We clearly see that this ice crystal loss is reduced if fewer ice crystals are present in the beginning. On the other hand, ice crystal loss is more substantial for ambient temperatures above 225K.
Looking at the aged contrail-cirrus, we investigate in particular the evolution of the total extinction, which we assume to be a proxy of a change in the contrail climate impact. We observe that the initially prescribed ice crystal number, ambient temperature and relative humidity have a strong impact on the contrail lifecycle. Increasing the water vapour emission is, however, of secondary importance.

The total extinction of H₂ contrails is significantly lower than in the case of kerosene contrails. Hence, our simulations suggest that the usage of H₂ combustion as propulsion technology might strongly reduce the climate impact of a single contrail.

This work contributes to the collaborative effort of the German Aerospace Center (DLR) and Airbus in assessing the climate impact of H₂ contrails.

How to cite: Lottermoser, A. and Unterstraßer, S.: High-resolution modelling of contrails formed behind hydrogen-powered aircraft, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16300, https://doi.org/10.5194/egusphere-egu24-16300, 2024.

Contrails are estimated to account for the majority of the present-day warming by the aviation industry. Their formation relies on the availability of aerosol in the exhaust plume, upon which water vapour can condense and subsequently freeze to form contrail ice crystals Most modern aircraft operate in the soot-rich regime, releasing soot particles with a number emission index (EI_n) of between 10¹⁴ and10¹⁶ (kg-fuel)^-1. Under these conditions, the number concentration of soot particles and contrail ice crystals scales linearly. For this reason, existing global contrail simulations typically assume that the number concentration of ice crystals and soot particles are equivalent. However, the use of alternative fuels such as sustainable aviation fuel (SAF) and liquid hydrogen, and the adoption of cleaner lean-burn combustors in the existing fleet are likely to drive the soot EI_n into the soot-poor regime < 10¹³ (kg-fuel)^-1. Here, (semi) volatile material and entrained ambient particles can compete with soot for plume supersaturation and the relationship between the number concentration of soot particles and contrail ice crystals is non-linear. These effects are not currently accounted for in existing contrail models used to simulate regional and global contrail climate forcing.  

In this work, we extend the parcel model proposed by Kärcher et al. [1] to account for the activation of volatile particulate matter (vPM) in the soot-poor regime and integrate this into the contrail cirrus prediction model (CoCiP) [2]. We explore the relationship between the soot EI_n and the apparent ice emissions index (AEI) in the soot-rich and soot-poor regimes, evaluating the model’s sensitivity to different aerosol properties, including particle hygroscopicity and characteristics of the particle size distribution. Preliminary results show a linear relationship between the soot EI_n and AEI in the soot-rich regime, consistent with previous work [1]. However, in the soot-poor regime, the AEI: (i) could be up to two orders of magnitude larger than the soot EI_n; (ii) increases with decreasing ambient temperatures and (iii) depends on the assumed particle properties of the (semi) volatile and ambient particle modes. These results suggest that existing global contrail simulations may underestimate the contrail climate forcing for a small subset of flights with soot EI_n < 10¹⁴ (kg-fuel)^-1.

The model developed in this work will be implemented in a global contrail simulation, incorporating activation of vPM. A sensitivity analysis will also be performed, and the results validated with in-situ measurements from the recent Emissions and Climate Impact of Alternative Fuels (ECLIF) III experimental campaign [3].

References

[1] Bernd Kärcher et al., Journal of Geophysical Research: Atmospheres, 2015, 120, 7893–7927.

[2] Ulrich Schumann, Geoscientific Model Development, 2012, 5, 43–580.

[3] Raphael Märkl et al., [EGUsphere preprint].

How to cite: Ponsonby, J., Teoh, R., and Stettler, M.: Towards an improved treatment of (semi) volatile particle activation in contrail models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17410, https://doi.org/10.5194/egusphere-egu24-17410, 2024.

Condensation trails (contrails) are considered the main non CO2 effect of aviation on global warming (Lee 2021) However, the uncertainty remains important and therefore a better understanding of the physical process underlying contrail formation is required. For a Jet A-1 kerosene fuel burned with a rich burn engine, the formation of contrails is mainly due to the condensation of water around soots emitted by the engine. In the case of Sustainable Aviation Fuels (SAF) or lean burn engines, the soots emitted are in very weak quantity so to let other nucleation process to occur (Kärcher 2018) such as homogeneous nucleation based on water and sulfuric acid (Rojo 2014). In order to perform contrail formation simulation with the details of the jet dilution due to the interaction between the plume and the aerodynamic of the aircraft, it is important to include the nucleation process strongly coupled with the aerodynamic in the simulation. This has been done for nucleation around soots (Khou 2016) but not for homogeneous nucleation. In this work, we propose a mix Lagrangian Eulerian approach in order to evaluate the homogeneous nucleation.

Lee D.S. et al., The contribution of global aviation to anthropogenic climate forcing for 2000 to 2018, Atmospheric Environment, 2021

Kärcher B, Formation and radiative forcing of contrail cirrus, Nature, 2018

Rojo C. et al., Impact of alternative jet fuels on aircraft-induced aerosols, Fuel, 2014

Khou JC. et al., CFD simulation of contrail formation in the near field of a commercial aircraft: Effect of fuel sulfur content, Atmospheric Chemistry, 2016

How to cite: Bonne, N.: A mix Lagrangian Eulerian approach for volatile particles and contrails formation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15562, https://doi.org/10.5194/egusphere-egu24-15562, 2024.

Aircraft induced cirrus clouds are estimated to account for 57% of aviation’s current-day climate impact, but this value is highly uncertain with the fidelity and biases in meteorological data being significant contributing factors. Our work aims to address this uncertainty and to provide empirical evaluation of multiple contrail modeling approaches. First, we use a dataset of contrail cross sections observed from the CALIOP orbital LIDAR that were attributed to specific flights to calibrate parameterizations for the initial widths and depths of contrails. We then examine the effect of systematic biases in wind, humidity and temperature, analyzing which modifications to the data provide the best agreement between a simulated contrail (using the APCEMM contrail model) and observations. Finally, we evaluate the degree of accuracy of the calibrated APCEMM model across a larger dataset and compare the results to those from the widely-used CoCiP model.

How to cite: Xu, M., Meijer, V., Barrett, S., and Eastham, S.: Empirical Calibration of Contrail Models based on LIDAR Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10398, https://doi.org/10.5194/egusphere-egu24-10398, 2024.

The cirrus clouds impact on the radiation budget of the Earth depends mainly of their optical thickness and altitude (Heymsfield et al., 2017). The contrails formed from aircraft emissions bring an additional impact to that of natural cirrus clouds (Kärcher, 2018). Their formation and potential evolution in cirrus clouds depend on the thermodynamical state of the atmosphere at fine scales, in particular of the saturation of water vapour with respect to ice. However, at their altitude of formation (~10 km), few reliable measurements of the water vapour are available.

In this study, we use observational data on the presence of crystals through their scattering observed by lidar and water vapor measurements using the Raman scattering technique (Fréville et al., 2015). Observations from standard meteorological balloon soundings (temperature, water vapor, and wind) (Dupont et al., 2020), as well as meteorological reanalyses (ECMWF), will be also analyzed to better characterize the overall context, considering finer vertical resolutions.

A first part of this study is to evaluate the quality of Modem M10 radiosondes humidity measurements available from the MeteoFrance network by comparison with ECMWF ERA-5 analysis. A second part of this study is to document contrails formation and evolution using a combination of instruments: an ADS-B recorder to identify aircraft type and position, a full sky camera to detect the presence of contrails and a collocated lidar to retrieve water vapour concentration profiles and macrophysical and optical properties of the contrail. The methodology and first results will be presented on a case study identified the 2nd of June 2023 above Clermont-Ferrand (France). Contrails have been observed when ECMWF ERA-5 relative humidity was around 115% and stay visible on the full-sky camera during more than 2 hours. This study is carried out in the framework of the European project BeCoM (Grant agreement ID: 101056885) whose main objective is to reduce the contrail radiative forcing.

Keywords: water vapour, cirrus, contrail, Lidar, camera.

Bibliography:

Kärcher et al., (2018). Formation and radiative forcing of contrail cirrus. Nature communications, 9(1), 1824.

Heymsfield et al., (2017). Cirrus clouds. Meteorological Monographs, 58, 2-1.

Fréville et al. (2015). Lidar developments at Clermont-Ferrand – France for atmospheric observation, Sensors, 2015, 15, 3041-3069; doi:10.3390/s150203041

Dupont et al., (2020). Characterization and corrections of relative humidity measurement from Meteomodem M10 radiosondes at midlatitude stations. Journal of Atmospheric and Oceanic Technology, 37(5), 857-871.

How to cite: Diarra, S., Baray, J.-L., Montoux, N., Fréville, P., Peyrin, F., Cacault, P., and Keckhut, P.: Comparisons of radiosonde water vapor measurements with ECMWF ERA-5 and contrails observations above Clermont-Ferrand (France), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10040, https://doi.org/10.5194/egusphere-egu24-10040, 2024.

The so-called ice-supersaturated regions with air parcels in the status of ice supersaturation (ISSRs) are potential formation regions of cirrus, making them of particular interest to contrails and aviation-induced cirrus. Contrail persistence requires slight ice subsaturation to ice supersaturation (Lee et al., 2021; Li et al., 2023); otherwise, ice crystals would sublimate quickly. Contrails and contrail cirrus in regions with high relative humidity with respect to ice (RH_ice) have been derived to cause a net warming impact in earlier studies (Sausen et al., 2005; Stuber and Forster, 2007; Lee et al., 2021)

Seasonal and regional variabilities and long-term trends of upper tropospheric RH_ice and ISSRs have been studied using IAGOS routine measurements from passenger aircraft (Petzold et al., 2020; Rohs et al., 2023, see also https://www.iagos.org/). With increasing awareness of the strong climate impact of contrails and contrail cirrus among other aviation emissions, re-routing aircraft to avoid contrail formation becomes an important mitigation target for the aviation industry. However, the correct representation of ISSRs in forecast models is an essential prerequisite to plan robustly more climate-friendly flight trajectories.

In this work, we will show the status of weather forecast models in representing real upper tropospheric ice supersaturation. The near real-time RH_ice dataset from IAGOS observations, provided post-flight to Copernicus Atmosphere Monitoring Service (CAMS), are used to study the occurrence patterns and favourable spatial and temporal conditions of ISSRs in dense air traffic regions, e.g., the North Atlantic flight corridor. Cases demonstrating the assessment of ISSRs and contrail forecast models at cruise levels with in-situ aircraft observations will be showcased.

[Note: This work is conducted within the framework of the Horizon 2020 project ACACIA with Grant Agreement No. 875036 and the SESAR 3 JU project CICONIA with Grant Agreement No. 101114613.]

How to cite: Li, Y., Rohs, S., Blomel, T., Bundke, U., and Petzold, A.: Upper tropospheric humidity and ISSRs: near real-time flight data delivery, statistics, and application for contrail forecast model assessment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11846, https://doi.org/10.5194/egusphere-egu24-11846, 2024.

So far, the various components contributing to the global climate impact of aviation were mostly quantified and ranked on the basis of radiative forcings. However, regarding for example the Paris Agreement, the temperature change at Earth’s surface is the main target parameter, for which radiative forcing is only a proxy. A specific climate sensitivity parameter for contrail cirrus has, so far, not been established.

Here we close this gap for contrail cirrus with specially designed global climate model simulations, equipped with a coupled mixed layer ocean to determine the corresponding surface temperature change. For the first time the climate sensitivity and efficacy parameters were calculated for contrail cirrus. The efficacy of contrail cirrus to warm the Earth’s surface is found to be 62% smaller compared to CO₂ in the effective radiative forcing framework. That means that radiative forcings of same magnitude result in a much weaker surface warming for contrail cirrus than for CO₂. The origin of the reduced efficacy can be explained in detail by analyzing the related Feedback processes. An opposing response of the natural clouds (even in sign), with decreasing resp. increasing low- and mid-level clouds in case of CO₂ resp. contrail cirrus was found to be the main reason. In addition, a more negative Lapse-Rate Feedback was found for contrail cirrus, originating from a non-homogeneous vertical warming, with the largest temperature increase directly below contrail cirrus and decreasing in strength toward Earth’s surface.

The reduced contrail cirrus efficacy substantially affects contrail cirrus mitigation concepts when using climate metrics based on surface temperature change (e.g. GTP or ATR). Therefore, re-routing aiming for contrail cirrus reduction, but leading to an increased fuel consumption and additional CO₂ emissions might be much less effective than currently assumed.

How to cite: Bickel, M., Ponater, M., Burkhardt, U., Righi, M., Hendricks, J., and Jöckel, P.: Estimating the Climate Efficacy of Contrail Cirrus on Surface Temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18183, https://doi.org/10.5194/egusphere-egu24-18183, 2024.

Aviation has long been linked to environmental problems, including pollution, noise, and climate change. Although CO₂ emissions are the primary focus of public discussion, non-CO₂ emissions from aviation, such as contrails, nitrogen oxides, or cloud cover caused by aviation, can have comparable impacts on the climate. Previous studies have investigated the impact of different weather conditions on aviation and identified regions that are sensitive to climate change. They have also created data products, such as 4-dimensional climate change functions (CCFs), which enable air traffic management (ATM) to plan for climate-optimized trajectories. However, these functions were only derived for specific regions, seasons, and weather situations [1,2].

The presented research focuses on developing methods to determine the sensitivity of the atmosphere to aviation emissions in relation to climate effects. This is necessary to describe spatially and temporally dependent distributions, which are required to determine climate-optimized aircraft trajectories. While previous studies have focused on characterizing the North Atlantic Flight Corridor region [2], this study aims to extend the geographic scope by performing Lagrangian simulations for the extratropical regions of the northern hemisphere. The modular global climate model EMAC was used in this study to investigate contrail evolution on Lagrangian trajectories. The study analyzed the effects of contrails on the temporal evolution of key contrail formation parameters along these trajectories, as well as their effects on radiation in terms of the radiative forcing concept. With this comprehensive model, we can investigate the physical processes that determine the effects of contrails on climate and study their spatial and temporal variations.

The project leading to this study was funded by the European SESAR programme under Grant Agreement No. 101114785 (CONCERTO). High performance supercomputing resources were used from the German CARA Cluster in Dresden and the DKRZ Cluster in Hamburg.

References:  

[1] Matthes, S., Lührs, B., Dahlmann, K., Grewe, V., Linke, F., Yin, F., Klingaman, E. and Shine, K. P.: Climate-Optimized Trajectories and Robust Mitigation Potential: Flying ATM4E, Aerospace 7(11), 156, 2020.

[2]  Frömming, C., Grewe, V., Brinkop, S., Jöckel, P., Haslerud, A. S., Rosanka, S., van Manen, J., and Matthes, S.: Influence of weather situation on non-CO₂ aviation climate effects: the REACT4C climate change functions, Atmos. Chem. Phys., 21, 9151–9172, https://doi.org/10.5194/acp-21-9151-2021, 2021.

How to cite: Peter, P., Matthes, S., Frömming, C., and Grewe, V.: Contrail formation in mid-latitudes: Estimating the climate effect of contrails with climate change functions in EMAC using a Lagrangian approach., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20120, https://doi.org/10.5194/egusphere-egu24-20120, 2024.

Strategic planning of climate-optimal flight trajectories is one option to potentially reduce the climate impact of non-CO₂ aviation emissions. Such a measure builds upon detailed knowledge of climate response to aviation emissions at specific locations. So-called climate change functions (CCFs) were calculated by means of a Lagrangian approach within the atmospheric chemistry climate model system EMAC (ECHAM5/MESSy Atmospheric Chemistry Model) to provide this information. The CCFs contain temporally and spatially resolved information on the climate effect of standardized non-CO₂ aviation emissions, such as water vapour, nitrogen oxides, and effects of contrail cirrus. The initial CCFs were calculated for three specific summer and five winter weather situations covering the Northern Atlantic flight corridor (Frömming et al., 2021).

The present study (Frömming et al., in prep) describes updates over previous CCF calculations. These include the geographical expansion of the CCF domain from the Northern Atlantic towards EU and USA, the calculation of CCFs for a weather situation in spring, a higher spatial resolution for contrail CCFs, employing nudged climate model simulations enabling the comparison with observations, a consistent methodology for instantaneous to adjusted radiative forcing conversion, a more sophisticated choice of future emission scenario and the inclusion of efficacies.

As the calculation of CCFs demands very high computational effort, they cannot be used for operational eco-efficient flight planning. For that reason, more generally applicable algorithmic Climate Change Functions (aCCFs) were derived (van Manen and Grewe, 2019; Yin et al., 2023) based on statistics of weather-related similarities within the CCFs. The aCCFs require only a small number of local meteorological parameters taken from numerical weather forecast models and represent a fast methodology to predict the specific climate impact per unit emission for a certain location, altitude and time.

Since the new CCFs are located partially outside the initial aCCF domain and time, an independent comparison of CCFs and aCCFs is performed. Results indicate that, depending on species, particular attention is required, when aCCFs - developed for winter and summer - are transferred to other seasons, e.g. spring, when midlatitudes might be influenced by polar airmasses. Further studies expanding the spatial and temporal domains of CCFs appear necessary.

References:

Frömming, C., Grewe, V., Brinkop, S., Jöckel, P., Haslerud, A. S., Rosanka, S., Van Manen, J., and Matthes, S.: Influence of weather situation on non-CO₂ aviation climate effects: The REACT4C climate change functions, ACP, 21, 9151 – 9172, 2021.

van Manen, J. and Grewe, V.: Algorithmic climate change functions for the use in eco-efficient flight planning, Transportation Research Part D: Transp. Env., 67, 388–405, 2019.

Yin, F., Grewe, V., Castino, F., Rao, P., Matthes, S., Dahlmann, K., Dietmüller, S., Frömming, C., Yamashita, H., Peter, P., et al.: Predicting the climate impact of aviation for en-route emissions: the algorithmic climate change function submodel ACCF 1.0 of EMAC 2.53, GMD, 16, 3313–3334, 2023.

Frömming, C., Matthes, S., Dietmüller, S., Peter, P., Grewe, V., Dahlmann, K., Jöckel., P., Geographical extension and refinement of Climate Change Functions: AIRTRAC.Vxy (included in EMAC-MESSy d2.52), GMD, in prep.

How to cite: Frömming, C., Matthes, S., Dietmüller, S., Peter, P., Grewe, V., Dahlmann, K., and Jöckel, P.: Update of Climate Change Functions and comparison with algorithmic Climate Change Functions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17462, https://doi.org/10.5194/egusphere-egu24-17462, 2024.

Planning climate-optimized aircraft trajectories requires temporally and spatially resolved quantitative estimates of the climate effects of aviation emissions. Algorithmic climate change functions (aCCFs) are applied, which efficiently assesses the climate effects of CO₂ and individual non-CO₂ effects (i.e. nitrogen oxide (NO_x) induced ozone, methane and PMO, water vapour, and contrail-cirrus) using meteorological input data at the time and location of the emission. A consistent set of initial prototype aCCFs (aCCF-V1.0) has recently been made available (Yin et al., 2023), and an updated formulation of this aCCFs calibrated towards the climate response model AirClim has been developed (aCCF-V1.0A, Matthes et al., 2023).

Utilizing the recently published open source Python Library CLIMaCCF (Dietmüller et al., 2023), we calculate aCCFs for individual and merged non-CO₂ climate effects for a variety of different summer and winter weather patterns over the North Atlantic flight corridor as well as over the European airspace. The calculations are based on meteorological data from the ERA5 reanalysis dataset. Through a detailed analysis of these aCCFs, we identify meteorological conditions with large non-CO₂ climate effects and demonstrate the influence of these identified weather patterns on the mitigation potential.

We use ensemble members to systematically characterize the uncertainties arising from the limited predictability of weather forecasts for the weather patterns identified above. This allows to access the robustness of the climate effect estimates (and their mitigation potential). Moreover, we investigate the sensitivity of using different physical climate metrics and efficacy parameters and thus provide further insight to uncertainties linked to climate science.

We further investigate the dependence of aCCF patterns to differently resolved meteorological input data (temporal, spatial, and vertical variation). Based on this analysis, we provide recommendations regarding the level of complexity for such an advanced MET service. Additionally, sensitivity studies using meteorological data from different data products (i.e. archived historical forecast) are shown.

Acknowledgement: The current study has been supported by the following projects: CICONIA, which has received funding from the European Union under grant agreement no. 101114613, CONCERTO, which has received funding from the European Union under grant agreement no. 101114785 and the BMWK LuFo project D-KULT 20M2111A.

How to cite: Dietmüller, S., Matthes, S., Frömming, C., Peter, P., and Dahlmann, K.: Investigating periods and regions with large mitigation potential using algorithmic climate change functions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14735, https://doi.org/10.5194/egusphere-egu24-14735, 2024.

The climate impact of a flight is determined not only by the amount of aircraft emissions, but also by the time, location, and specific weather conditions at which such emissions occur. As a result, there is the potential of mitigating the climate impact of a flight by optimizing its trajectory. This operational strategy presents trade-offs between minimizing the climate impact from carbon dioxide (CO₂), which only depends on the amount of emitted CO₂, and minimizing the so-called non-CO₂ effects of aviation, due to the radiative forcing from contrails and contrail cirrus, the perturbation of atmospheric concentrations of ozone and methane caused by NO_x emissions, and H₂O emissions at high flight levels. Moreover, operating costs and climate impact are expected to be conflicting objectives for trajectory optimization (Grewe et al., 2014). The characteristics of the sets of Pareto optimal solutions resulting from such multi-objective optimizations would, however, vary under different atmospheric conditions.

To compare the benefits and costs associated to this operational strategy under different weather patterns, we use the air traffic simulator AirTraf, which optimizes aircraft trajectories based on the atmospheric fields computed by the ECHAM/MESSy Atmospheric Chemistry (EMAC) model (Yamashita et al., 2020). This modelling chain presents the advantage of enabling the analysis of optimized aircraft trajectories over a large number of consecutive days, identifying preferred compromise solutions between multiple optimization objectives (Castino et al., 2023). In the present study, we consider four winter and four summer seasons between 2015 and 2019, optimizing 100 flights over the North Atlantic Corridor (NAC) on each simulation day. Subsequently, we compare trajectories minimizing different objective functions, including fuel used, and the potential formation of contrails along the trajectory. We classify the weather patterns by comparing their similarity to the positive and negative phases of the North Atlantic Oscillation (NAO) and East Atlantic (EA) patterns, applying the methodology  presented by Irvine et al. (2013). As a result, we can identify which conditions are correlated to a larger potential of mitigating the climate impact of our air traffic sample, e.g., by reducing the formation of persistent contrails.

Acknowledgment: This research has received funding from the Horizon Europe Research and Innovation Actions programme under Grant Agreement No 101056885.

References:

• Irvine, E. A., et al.: Characterizing North Atlantic weather patterns for climate-optimal aircraft routing, Meteorological Applications, 20, 80 – 93, https://doi.org/10.1002/met.1291, 2013.
• Grewe, V., et al.: Reduction of the air traffic's contribution to climate change: A REACT4C case study, Atmospheric Environment, 94, 616 – 625, https://doi.org/10.1016/j.atmosenv.2014.05.059, 2014.
• Yamashita, H., et al.: Newly developed aircraft routing options for air traffic simulation in the chemistry–climate model EMAC 2.53: AirTraf 2.0, Geoscientific Model Development, 13, 4869 – 4890, https://doi.org/10.5194/gmd-13-4869-2020, 2020.
• Castino, F., et al.: Decision-making strategies implemented in SolFinder 1.0 to identify eco-efficient aircraft trajectories: application study in AirTraf 3.0, Geosci. Model Dev. Discuss. [preprint], https://doi.org/10.5194/gmd-2023-88, in review, 2023.

How to cite: Castino, F., Yin, F., Grewe, V., and Yamashita, H.: Mitigation potential of optimized aircraft trajectories and its dependency on weather patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16759, https://doi.org/10.5194/egusphere-egu24-16759, 2024.

Aviation outflow is the only anthropogenic source of pollution that is directly emitted into the upper troposphere and potentially alters cloud patterns by creating linear contrails. These contrail cirrus formations can either increase high-cloud cover in supersaturated, cloud-free air or modify the microphysics of existing natural cirrus clouds. Despite the likelihood of aircraft intersecting natural cirrus, the extent of their impact remains uncertain.

Our study interests using the ICON_NWP model, integrated with a two-moment cloud microphysical scheme, to simulate contrail formation and dynamics. Central to this research is examining how aviation aerosols and emitted water vapor influence contrail development within already existing cirrus clouds.

The number of surviving nucleated ice crystals after the jet phase depends on engine and fuel parameters as well as on the ambient atmosphere (Kärcher et al 2015) and displays large regional variation (Bier & Burkhardt, 2019).  Bier and Burkhardt (2022) demonstrated that the concentration of ice crystals after the jet phase varies, ranging in terms of ice particle concentrations from 160 to 200 cm-3 over the North Pacific.

We assume a suggestive fixed-wing span of 50 meters, typical of aircrafts such as Airbus 300 and Boeing 737, correlating to a water vapor emission rate of 10 g per meter of flight. In our simulations, contrail formation is initiated at 450 seconds, marking the end of the vortex phase. Beyond this point, the remaining ice crystals are predominantly influenced by atmospheric conditions. Within each grid box, our initial step involves assessing the critical contrail temperature according to the Schmidt-Appleman criterion. Depending on whether these criteria are met, we then proceed to either introduce ice crystals or add the corresponding amount of water vapor.

Ultimately, we compare our simulation results with corresponding aircraft data, utilizing the DARDAR-NICE dataset that offers height-resolved measurements within cirrus clouds, to validate the imprints of aircraft emissions.

How to cite: Marjani, S. and Quaas, J.: Exploring the Interaction between Aircraft Emissions and Cirrus Clouds: Through Simulation Techniques and Satellite retrievals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16260, https://doi.org/10.5194/egusphere-egu24-16260, 2024.

Non-CO₂ emissions contribute to climate effects from aviation in the same order of magnitude as carbon dioxide (CO₂) emissions. However, the non-CO₂ effects, comprising e.g., ozone and methane induced from NO_x emissions, together with contrails, or the indirect aerosol effects, are associated with much larger uncertainties. The EU Aeronautics project ACACIA (Advancing the SCience for Aviation and ClimAte) explored the climate impacts of non-CO₂ effects which show a strong dependence on atmospheric conditions and synoptic situation. While CO₂ and non-CO₂ effects in general introduce a warming effect for climate change, some indirect effects might result in a relatively large cooling.

ACACIA investigated indirect aerosol effects comprising formation and properties of clouds. Atmospheric conditions for the formation of long-lived contrails have been investigated, with the aim to improve their predictability. Indirect effects of nitrogen oxide emissions on atmospheric ozone and methane have been estimated, using a set of global chemistry-climate models. These different effects have been brought to a common scale by various physical climate metrics. A dedicated study on prevailing uncertainties has been performed, with the goal to provide robust recommendations considering uncertainties of individual estimates. Together with the numerical studies a dedicated analysis of existing measurement data has been completed in order to identify needs and requirements for atmospheric observations.

To this end, ACACIA brought together research across scales, from plume to global scale, from laboratory experiments to global models resulting in a series of scientific publications, and it proceeds from fundamental physics and chemistry to the provision of recommendations for policy, regulatory bodies, and other stakeholders in the aviation business. 

Acknowledgements This project ACACIA (Advancing the scienCe for Aviation and ClImAte) receives funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 875036. High performance supercomputing resources were used from the German DKRZ Deutsches Klimarechenzentrum Hamburg.

How to cite: Matthes, S., Bellouin, N., Dedoussi, I., Fuglestvedt, J., Gierens, K., Hauglustaine, D., Kanji, Z., Krämer, M., Lee, D., Lohmann, U., Petzold, A., Quaas, J., Righi, M., and Weinzierl, B.: Advancing understanding on aviation's non-CO2 climate effects through combination of numerical modelling and observations: ACACIA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18806, https://doi.org/10.5194/egusphere-egu24-18806, 2024.

Anthropogenic transport sectors are concerned by their climate effects which results from CO₂ and non-CO₂ effects, comprising NO_x-induced changes of atmospheric ozone and methane. Here climate-chemistry models are required to advance our understanding on induced changes of reactive species and the associated radiative forcing associated to aviation emissions. Evaluation of such comprehensive models is key in order to be able to investigate associated uncertainties can use observational datasets from research infrastructures like IAGOS and DLR aircraft measurement campaign data, as well as ground-based observations.

We use the MECO(n) system which is a “MESSy-fied ECHAM and COSMO nested n-times”, relying on the Modular Earth Submodel System (MESSy) framework. For this purpose, both models have been equipped with the MESSy infrastructure, implying that the same process formulations (MESSy submodels) are available for both models. Modelled atmospheric distributions from the multi-scale model system MECO(n) are systematically compared to observational data from aircraft measurements in the upper troposphere and lower stratosphere. Nudging of meteorology to reanalysis data, and special diagnostics available within the modular MESSy infrastructure are implemented in the numerical simulations. Online sampling along aircraft trajectories allows to extract model data with a high temporal resolution (MESSy submodel S4D), in order to evaluate model representation and key processes. Beyond systematic evaluation with IAGOS scheduled aircraft measurements, particular focus on those episodes where dedicated measurements from aircraft campaigns are available.

We present an analysis of reactive species, NO_y and ozone, which also identifies those weather pattern and synoptic situations where transport sectors, comprising aviation contributes strong signals. We evaluate model representation of the NO_x-induces effect on radiatively active species ozone and methane via the hydroxyl radical in both model instances, ECHAM5 and COSMO. This is key for advancing the scientific understanding of NO_x-induced effects from transport effects required in order to quantify potential compensation and trade-offs and eventually in order to identify robust mitigation options for sustainable anthropogenic transport sectors.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 875036 (ACACIA, Advancing the Science for Aviation and Climate). This work uses measurement data from the European Research Infrastructure CARIBIC/IAGOS. High-Performance Super Computing simulations have been performed by the Deutsches Klima-Rechenzentrum (DKRZ, Hamburg) and the Leibniz-Rechenzentrum (LRZ, München).

How to cite: Dahlmann, K., Matthes, S., Nickl, A.-L., Peter, P., Mertens, M., Ziereis, H., Harlaß, T., and Zahn, A.: Transport-induced changes of atmospheric composition in the UTLS in the multi-scale Earth system model MECO(1), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19971, https://doi.org/10.5194/egusphere-egu24-19971, 2024.

Over the last decades, the increasing globalisation and the associated need for substantially shortened travel times has led to public and privately-funded development of supersonic aircraft. The International Civil Aviation Organization (ICAO) needs to define standards for the advent of this new generation of supersonic aviation. The SENECA project (“noiSe and EmissioNs of supErsoniC Aircraft”) aims at developing supersonic aircrafts, investigating the impact of specifical supersonic engine technologies on the aircraft performance and noise, providing aircraft fuel burn, emitted CO2 data and engine emission indices for NOx, CO, HC, SOx and soot and quantifying a range of climate impacts of supersonic aviation.

In the context of this project, the ONERA objectives are to model and characterize the contrails due to supersonic aircraft during cruise and to provide data to climatologists to calculate their global impact.

In this study, a focus is made on the vortex phase of the contrail aging modelled with the CEDRE software from ONERA. The vortex phase strongly depends on both the aircraft geometry and the atmospheric conditions. So, first RANS simulations using mesh adaptation were performed to obtain an aerodynamical field used to initialize the vortex phase [1]. 

From the RANS field, a slice far from the aircraft is extracted, extruded and interpolated on a 3D mesh whose longitudinal dimension corresponds to the Crow wave length. Jet and atmospheric fluctuations are added to trigger the Crow instability, and the stratification of the atmosphere is also modelled corresponding to the lower stratosphere where the aircraft is flying in cruise regime. After those steps, a LES simulation is performed to simulate the contrail aging.

[1] M. Muller and E. Terrenoire, Near-field mesh adaptation for contrail modeling of a supersonic aircraft, 3AF International Conference on Applied Aerodynamics, 29-31 March 2023, Bordeaux, France

How to cite: Muller, M., Terrenoire, E., Bouhafid, Y., and Bonne, N.: Contrail aging simulation of a supersonic aircraft, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9776, https://doi.org/10.5194/egusphere-egu24-9776, 2024.

How to cite: Euchenhofer, M. V., Ross, I., Eastham, S. D., Meijer, V., and Waitz, I. A.: A comparison of contrail detectability from LEO and GEO satellite images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12227, https://doi.org/10.5194/egusphere-egu24-12227, 2024.

The climate impact of aviation can be separated into CO2 and non-CO2 effects, with the latter being potentially larger than the former. In this
context we are more specifically interested in condensation trails (hereafter contrails) and induced cirrus. Monitoring contrail formation and evolution is
necessary to understand their radiative effects and help the aviation industry to transition towards a more sustainable activity. Current research aimed at
detecting contrails is mostly based on geostationary satellite images because they allow to follow the contrail over a long period of time. However a major
shortcoming is that the formation phase of the contrails cannot be detected and larger, but older, contrails cannot always be attributed to the flights
that produced them. To circumvent the problem that satellite images do not have a sufficient resolution to observe the contrail formation phase, we
use a ground-based hemispheric camera with a two-minute sampling rate as a complementary source of information. As a first step, we have developed
a traditional morphological algorithm that will help preparing a sufficiently large labelled database as required to train a deep-learning algorithm. Our
algorithm aims to detect whether each aircraft that passes in the field of view of the camera (as monitored from an ADSB radar) produces a contrail or not. We are thus able to relate contrail formation and evolution with aircraft
type, flight altitude and weather conditions. We start by focusing on the young linear contrails that appears just behind the aircraft. We also consider
all weather conditions except completely cloudy conditions that prevents contrails to be observed. The algorithm combines various morphological
treatments to binarise the image and a linear Hough transform to identify straight lines in a direction close to the aircraft’s trajectory. Its performance is evaluated against a database that was manually annotated consisting of 400 images with 407 contrails. We find that our algorithm has a specificity
of 97%, i.e. there are few false detections, but its sensitivity is about 55%, i.e. it is missing a significant fraction of contrail appearances. Looking in
more details, the sensitivity is 60% in clear-sky contidions but only 40% in conditions of a thin high cloud cover with superimposed contrails. An
analysis of several years of contrail detection will be presented to determine precisely the fraction of contrail-producing flights and the associated weather
conditions with non-persistent and persistent contrails.

How to cite: Gourgue, N., Boucher, O., and Barthes, L.: A Morphological Algorithm for the Detection of Linear Contrails, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14802, https://doi.org/10.5194/egusphere-egu24-14802, 2024.

A recent study (Lee et al., 2021) has shown that contrails are the main contributor to aviation-related radiative forcing. However, the same study shows that this contribution is highly imprecise due to numerous uncertainties. Among the most important are the numerous contingencies regarding the vertical and horizontal extent of ice plumes, as well as their altitude, which may differ from the flight level of the emitting aircraft, rising to hundreds of meters. This uncertainty is largely due to its interaction with the aircraft’s dynamic wake, which, very soon after the aircraft’s passage, is reduced to two counter-rotating vortices known as wingtip vortices.

These two vortices descend by induction into the atmosphere, driving the plumes to lower altitudes. However, these dynamics are influenced by atmospheric stratification, as shown in Spalart (1996). In most cases, the two wake vortices continue their descent, but certain dynamic structures are created in their vicinity by the baroclinic torque due to buoyancy, and rise to flight altitude. The wake then splits into two parts: one descending into the atmosphere and the other rising back up to, or slightly above, flight altitude. A long, rising column of fluid joins the two wakes. The plume initially trapped around the two vortices can then evolve in three different ways. Either the plume remains with the vortices well below the flight altitude, or it rises to this altitude or even higher, entrained in the secondary wake, or it is distributed between the two wakes and the column uniting them, as shown by Saulgeot et al. (2023).

Among the parameters influencing these dynamics is the relationship between atmospheric stratification, quantified by the Brunt-Väisälä frequency N, and the characteristic time τ₀ of the vortex dipole

                                                                   τ₀ = b₀/ W₀

where the natural motion of the vortices is a descent at constant speed W₀ caused by mutual induction. This is the reference time scale, and the initial vortex separation b₀ is the reference distance. In this scale framework, the effective stratification of the vortex flow is measured by the inverse of the Froude number

                                                                    Fr⁻¹ = Nτ₀.                                                                  

The intermediate vorticity column plays a fundamental role in the upwelling of the plume: it is the only link between the primary and secondary wakes and can therefore influence both the latter and the plume. At the end of the two-dimensional phase of wake evolution, before the onset of the Crow instability, this column can destabilize, isolating the two parts of the wake and preventing the plume from rising. This can be thought of as thermal plume jet instabilities. These are of two types: sinusoidal and varicose. In most cases, the two instabilities follow one another (see figure 1): the varicose instability appears first, then the sinusoidal instability takes over due to a higher growth rate. Nevertheless, the appearance of one or the other can be observed independently.

Figure 1: Vorticity field for Fr⁻¹ =0.6. (a) t =7.3τ₀; (b) t =7.4τ₀; (c) t =7.5τ₀; (d) t =7.6τ₀; (e) t =7.7τ₀; (f) t =7.8τ₀; (g) t =7.9τ₀.

How to cite: Saulgeot, P., Brion, V., Bonne, N., Dormy, E., and Jacquin, L.: Two-dimensional stability of a wake vortex dipole in a stratified atmosphere., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12820, https://doi.org/10.5194/egusphere-egu24-12820, 2024.

Analyzing the formation of contrails on emissions from the most recent generation of aircraft engines is key to understand the climate impact from aviation. As for conventional Rich-Quench-Lean engines contrail ice crystals mainly form on a high number of emitted soot particles, the question arises which and how many particles are activated during the contrail formation process if soot emissions are strongly reduced through the Lean Combustion technology.

The ecoDemonstrator experiment is a collaboration between Boeing, GE, NASA, DLR and other international partners and took place in October 2023. For the first time, we present in-flight measurements of contrail ice crystals in the exhaust of the ultra-low soot emitting CFM International LEAP-1B engine. This experiment combines the lean-burning engine technology with the use of Sustainable Aviation Fuels (SAF) and ultra-low sulfur kerosene (LS-Jet-A) in newly manufactured engines to achieve close to soot-free emissions. During the experiment, we performed measurements on board the NASA DC-8 research aircraft, sampling emissions behind a Boeing 737 MAX 10 aircraft. In addition to gas and particle emissions, we also measured the number concentrations of ice crystals that formed behind the 737 MAX 10 at a distance between 3 and 8 kilometers with two Cloud and Aerosol Spectrometers (CAS) that were positioned on the upper and lower fuselage of the DC-8. We show a first analysis of the contrail ice data for selected flights and present apparent ice emission indices (AEI) in relation to ambient conditions.

How to cite: Bräuer, T., Märkl, R., Scheibe, M., Sauer, D., Dischl, R., Heckl, C., Aufmhoff, H., Stremming, L., Voigt, C., Digangi, J., Diskin, G., Baughcum, S., Griffin, W., Rahmes, T., Miller, C., and Moore, R.: In-flight Measurements of Contrails in the Low Soot Regime during the ecoDemonstrator Experiment , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10277, https://doi.org/10.5194/egusphere-egu24-10277, 2024.

Nitrogen oxides, emitted from air traffic, are of concern due to their impact on climate by changing atmospheric ozone and methane levels. Using the DLR research aircraft Falcon, total reactive nitrogen (NOy) measurements were carried out at high altitudes to characterize emissions in the fresh aircraft exhaust from the latest generation Rolls-Royce Trent XWB-84 engine aboard the long-range Airbus A350-941 aircraft. The impact of different engine thrust settings, monitored in terms of combustor inlet temperature, pressure, and engine fuel flow, was tested for three different fuel types under similar atmospheric conditions: Jet A-1, for the first time a 100% sustainable aviation fuel (SAF), and a blend of both fuels. In addition, a range of combustor temperatures were tested during ground emission measurements. We confirm that the NOx emission index increases with increasing combustion temperature, pressure and fuel flow. We find that as expected, the fuel type has no measurable effect on the NOx emission index. These measurements are used to evaluate cruise NOx emission index estimates from three engine emission models. Our measurements thus help to evaluate the ground to cruise correlation of current engine models, serve as input for climate modelling, and extend the extremely sparse data set on in-flight aircraft NOx emissions to newer engine generations.

How to cite: Roiger, A., Harlass, T., Braeuer, T., Schlager, H., Schumann, U., Sauer, D., Voigt, C., Doernbrack, A., Maerkl, R., Dischl, R., Schripp, T., Bondorf, L., Grein, T., Gauthier, M., Renard, C., Luff, D., Johnson, M., Madden, P., Swann, P., and Sallinen, R.: In-flight and ground-based measurements of nitrogen oxide emissions from latest generation jet engines and 100% sustainable aviation fuel, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19754, https://doi.org/10.5194/egusphere-egu24-19754, 2024.

The radiative forcing of aviation aerosol-cloud interactions remains very uncertain. Its quantification relies on climate models. One of the main drivers of aerosol concentrations and long-range vertical and horizontal transport in climate models is wet scavenging, which can be parameterised in different ways with several tunable parameters. In this work, we use the LMDZ-OR-INCA climate to investigate the impact of different scavenging parameterisations on aerosol transport, using regional and seasonal vertical profiles obtained from ATom and HIPPO airborne measurements to discriminate between parameterisations. Results show that the residence time and the mass budgets of BC from all sources are both significantly influenced by the scavenging parameterisation. Moreover, the ability of a BC scavenging parameterisation to simulate vertical aerosol concentration profiles depends on geographical location, altitude and season. Near-surface aerosol concentrations, mainly due to Landing and Take-off Operations (LTO), are also affected by the choice of a wet scavenging parameterisation. Results suggest it may be possible to design a new scavenging routine for LMDZ-OR-INCA model to better represent the long-range transport of aviation aerosols and reduce uncertainties in aviation aerosol-cloud interaction radiative forcing.

How to cite: Février, N., Hauglustaine, D., and Bellouin, N.: Improving aviation aerosol scavenging representation in LMDZ-OR-INCA model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19989, https://doi.org/10.5194/egusphere-egu24-19989, 2024.

Due to rapid urbanization and population growth, high aerosol pollution in the Korean Peninsula has become a major environmental concern. High concentrations of PM_2.5 in atmosphere is not only highly hazardous to humans, but also contributes significantly to visibility degradation and climate change. In study, K-means clustering analysis was performed to classify major synoptic patterns on the Korean Peninsula during the seasonal PM_2.5 management from 2015 to 2019. Also, we analyzed synoptic patterns according to the air quality on each cluster by dividing the PM_2.5 pollution standard into four levels to identify the differences in the occurrence of PM_2.5 concentrations in the similar meteorological environment. As a result, the synoptic patterns were classified into five clusters (C1~C5). The clusters (C1, C3, C4) with pressure gradient from east to west showed differences of PM_2.5 concentrations in Seoul as the pressure gradient between east and west changed. The clusters (C2, C5) with pressure gradients from south to north had different PM_2.5 concentrations in Seoul depending on the location and intensity of high pressure located in southeast of the Korean Peninsula and the intensity and location of high- and low-pressure systems located in the North Pacific and Kamchatka Peninsula, respectively. This study confirmed that air quality can vary depending on the location and strength of high- and low-pressure systems in the similar synoptic meteorological environment.

How to cite: Chae, D., Kim, J., Yoo, J.-W., and Lee, S.-H.: A study of differences in PM2.5 concentrations at similar synoptic meteorological fields during the seasonal PM2.5 management from 2015 to 2019, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7334, https://doi.org/10.5194/egusphere-egu24-7334, 2024.

The shipping industry is a significant source of both SO₂ and NO_x, two air pollutants which have neg-active implications for climate and air quality. SO2 is heavily regulated such that January 2020 marked a global reduction of the maximum permitted sulfur fuel content (SFC) in shipping fuel from 3.5% to 0.5% by mass. There are also various limits on NO_x in coastal and inland waterways with more widespread NO_x emissions limits likely to be implemented in the future. The anticipated effect of the new regulations is an improvement of coastal air quality, but there is a potential drawback in terms of reducing the climate cooling effect of SO₂ caused by a change in cloud properties. However, the difficulty in measuring emissions from ships means that the overall impact and level of compliance with new and future regulations is unclear. Therefore, monitoring strategies capable of providing regular and long-term measurements of air pollutant emissions from the shipping industry are essential for fundamental research and compliance monitoring. Here we present top-down methodologies for calculating the SFC, along with emission ratios of ∆NO_x/∆CO₂ from individual ships. First, we demonstrate the application of an airborne platform to perform targeted measurements of ship plumes in the English Channel and Atlantic shipping lanes, allowing the comparison of emissions inside and out of sulfur emission control areas (SECAs). Second, we implement a stationary, point-sampling approach to measure ships arriving and departing two European ports.

Our results show there has been a significant reduction in the SFC of ships in the open ocean shipping lanes due to the new emission regulations, with most ships now well below the 0.5% limit imposed in 2020. Our measurements also show good agreement with a comprehensive ship specific emissions inventory (the Ship Traffic Emission Assessment Model – STEAM). This confirms the validity of models that use the new sulfur limit for radiative forcing calculations. In terms of NO_x, the measured ∆NO_x/∆CO₂ ratios were generally greater than those from diesel vehicles operating within a typical European fleet, suggesting ships could be a significant source of NO_x to cities, especially where ports are close to populated areas. It is envisaged that the presented methodologies could be implemented to facilitate widespread monitoring of ship emissions, which could provide the basis for policy formulation and validation.

How to cite: Lee, J., Pasternak, D., Wilde, S., and Lacy, S.: SO2 and NOx emissions from European shipping: a measurement study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10092, https://doi.org/10.5194/egusphere-egu24-10092, 2024.

As air quality targets become more stringent, a better understanding of urban air pollution sources continues to be important for the development of targeted and effective policy.  Ambient measurements of the enhancement of NOx and CO₂ concentrations above background can be linked to direct emissions via the calculation of emission ratios (ΔNOx/ΔCO₂), which in turn provide insight into emission sources. In this work, we use a regression analysis method to quantify emission ratios from high time resolution (1 second) roadside measurements of NOx and CO₂ taken in two major UK cities, London and Manchester. Calculated emission ratios allow us to gain a greater understanding of the effect of factors such as fleet composition and vehicle operating conditions on NOx emissions, along the roads measured. Additionally, a comparison of emission ratios across the two cities allows for an interesting discussion on the differences in traffic behaviour and effectiveness of local traffic-related policy (e.g. low emission zones). Analysis of long-term measurements of NOx and CO₂ at the Marylebone Road site demonstrate the effect of changes in vehicle technology and the effect of the ULEZ. This work also aims to highlight the benefit of long-term high time resolution measurements on a local level to develop an advanced understanding of local traffic-related NOx emission characteristics.

How to cite: Williams, C., Drysdale, D. W., Cliff, D. S., Moller, D. S., and Lee, P. J.: Use of high-time resolution roadside measurements to inform NOx emission ratios , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6075, https://doi.org/10.5194/egusphere-egu24-6075, 2024.

The Eastern Mediterranean experiences a rapid acceleration of climate warming mainly due to the continuous growth of greenhouse gases (GHG) in the atmosphere. Carbon dioxide (CO₂) is a key contributor to the human-induced greenhouse effect due to its long lifetime and high atmospheric concentrations. With its levels continuing to rise, the need to mitigate its emissions is of utmost importance. Towards this direction, atmospheric models are used to assess the influence of emissions on atmospheric composition. Emission fields used in models, called bottom-up emission inventories, provide information on the amounts and the distribution of the emitted pollutants. However, these emissions are coupled with large uncertainties at small spatiotemporal scales. Therefore, optimization of these emission estimates is needed to increase accuracy and thus support the identification of targets for emission reduction. In this study, we are optimizing the anthropogenic emissions of CO₂ over Greece by using the data assimilation system CTDAS-WRF (Carbon Tracker Data Assimilation Shell) that uses an Ensemble Kalman filter data assimilation method. As a forward model, we use WRF-CHEM with the GHG mechanism that allows passive tracer transport of CO₂. The sum of emissions from all different anthropogenic sectors from the CAMS anthropogenic emission inventory (CAMS-GLOB-ANT 5.3) is used as input to the model, in addition to biogenic (VPRM) and biomass burning emissions (FINN 2.5). The simulations are then compared to in-situ, FTIR and satellite observations of CO₂ that have been assimilated by CTDAS. The differences between the observations and the simulations are assumed to be only due to the uncertainty of the anthropogenic emissions. Therefore, our system is optimizing only these emissions. Preliminary results show the largest underestimates by the bottom-up inventories over the city of Athens.

How to cite: Gialesakis, N., Daskalakis, N., Reum, F., Vrekoussis, M., and Kanakidou, M.: Inversions of anthropogenic CO2 emissions using CTDAS-WRF over Greece in the East Mediterranean., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-671, https://doi.org/10.5194/egusphere-egu24-671, 2024.

How to cite: Yang, Y.: Elucidating the Impacts of Various Atmospheric Ventilation Conditions on Local and Transboundary Ozone Pollution Patterns: A Case Study of Beijing, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1644, https://doi.org/10.5194/egusphere-egu24-1644, 2024.

Polycyclic aromatic hydrocarbons (PAHs) in the atmospheric environment are almost exclusively formed in combustion processes. Oxygenated and nitrated PAHs are co-emitted with parent PAHs from fossil fuel and biomass combustion processes, and many are formed in photochemical and microbiological reactions of PAHs in air and soil. As semivolatiles resisting biodegradation in soils and surface waters to some extent, polycyclic aromatic compounds (PACs) i.e., PAHs and their derivatives, can be subject to re-volatilisation., which may turn soils and surface waters from sinks into secondary sources and enhances the long-range transport potential of PACs by multihopping (grasshopper effect). The significance of these secondary sources for PAC abundances in ambient air is unknown and is not accounted for in emission inventories. Gaps in PAH emission inventories have been indicated by field studies in various countries.

We determined the concentrations of 15 parent, 10 oxygenated and 17 nitrated PAHs in air and soils at a rural and near-coastal northern European site and a central European rural background site, and in air and surface seawater at two off-shore sites in the eastern Mediterranean and along NW-SE transects in the Mediterranean. Directions of air-soil and air-sea exchanges were derived from the substances’ fugacities.

At the central European site, a number of 2-4 ring PACs were found to volatilise from grassland and more from forest soils in summer, and much less in winter. Conversely, at the receptor site in northern Europe, net deposition of PACs prevails and re-volatilisation occurs only sporadically. In the Mediterranean, 3-4 ring PAHs and dibenzofuran are found to volatilise in most seasons.

Existing data on air-surface exchange of PACs is notably scarce, and methodological uncertainties persist in quantifying air-soil exchange. As very little is known about the spatial and seasonal distributions of PACs soil burdens and net mass fluxes, an assessment of the significance of soils and surface waters as secondary sources of PACs in the air of source and receptor areas is not possible.

How to cite: Lammel, G., Bandowe, B. A. M., Bohlin-Nizzetto, P., Degrendele, C., Halse, A. K., Iakovides, M., Kukučka, P., Kyprianou, M., Martiník, J., Mwangi, J., Palátová Nežiková, B., Přibylová, P., Prokeš, R., Sáňka, M., Sobotka, J., Vinkler, J., Wietzoreck, M., Pöschl, U., Stephanou, E. G., and Tsapakis, M. and the PAC air-surface exchange: Soils and surface waters are secondary sources of polycyclic aromatic compounds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17795, https://doi.org/10.5194/egusphere-egu24-17795, 2024.

Indore grapples with severe air quality challenges due to rapid urban development, posing significant public health risks. To investigate the source contributions, it is vitally important to distinguish the contribution of local emissions and regional emissions. This study employs the WRF-Chem model in tracer mode to discern the contributions of PM_2.5 and CO emissions from diverse regions over Indore, India. We identify the different high-emission contributing local and transboundary 25 regions and sources of particulate matter and CO emissions in Indore using WRF-Chem model during 2019.  The model utilizes a two-domain configuration. Model simulations successfully capture the spatial distributions of key meteorological parameters over the domain when compared to various datasets such as IMERG, MOPITT, and ERA5.  Results reveal that CO anthropogenic sources, both local and transported across domain boundaries, significantly contribute to concentrations in Indore. While the general spatial distribution of simulated CO aligns with MOPITT, simulated values are comparatively lower due to the exclusion of secondary sources and biogenic emissions. PM_2.5 in Indore itself is a main source of emissions with contributions exceeding 16% throughout the year, whereas biomass burning emerges as the primary source of PM_2.5 during specific months, with a consistent contribution observed throughout the year within the Indore district boundary. From an effective mitigation strategy perspective, further, we have combined local emissions and CAMS emissions in the model for the quantification of various pollutants over the Indore region.  We estimated the various sectoral contributions from residential, industry, transport, DG sets, eateries, brick kilns, and crematoriums with high spatial resolution using Weather Research and Forecasting with a Chemistry model.

How to cite: Tikle, S., Bouarar, I., Kumar, R., and Brasseur, G.: Source attribution modeling of PM2.5 and CO in Indore, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16230, https://doi.org/10.5194/egusphere-egu24-16230, 2024.

Within the scope of the ZEDU1 (Zero Emission Drive Unit Generation 1) project, both a conventional electric vehicle as a reference model and a prototype of the Zero Emission Drive Unit were developed for measurement characterizations. Concurrently with the demonstrator development, examinations of cast iron and hard-coated brake discs were conducted under real operating conditions and on test benches. Special attention was paid to the influence of recuperation on the airborne particle emissions from the brakes. Advanced on-board measurement methods were developed and effectively utilized.

The results highlight that the brake temperature significantly influences particle generation in the range of 10 nm, while the braking process primarily produces particles between 200 nm and 300 nm. Impressively, the use of regenerative braking during real driving led to a reduction in abrasion emissions of up to nearly 90%. Furthermore, a reduction of up to 83% in airborne brake abrasions for particle sizes ranging from 300 nm to 10 µm was observed with hard-coated brake discs.

Moreover, a novel brake system without airborne abrasion emissions was developed and validated. A demonstrator vehicle, equipped with the newly developed ZEDU1 unit, was designed, measured, and assessed for its everyday usability. Comprehensive tests confirm the complete functionality and durability of the developed brake system, thus showcasing its practicality

How to cite: Reiland, S., Philipps, F., and Arens, L.: Brake and Tire Emission Analysis with the Zero-Emission-Drive-Unit-Demonstrator for Battery Electric Vehicles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19733, https://doi.org/10.5194/egusphere-egu24-19733, 2024.