A5020527825- Atmospheric chemistry and aerosols
- Atmospheric aerosols and clouds
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Meteorological Phenomena and Simulations
- Climate variability and models
- Aeolian processes and effects
- Air Quality Monitoring and Forecasting
- Air Quality and Health Impacts
- Cryospheric studies and observations
- Topological Materials and Phenomena
- Arctic and Antarctic ice dynamics
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Fire effects on ecosystems
- Icing and De-icing Technologies
- Vehicle emissions and performance
- Tropical and Extratropical Cyclones Research
- Climate Change and Geoengineering
- Graphene research and applications
- Quantum and electron transport phenomena
- Rare-earth and actinide compounds
- Advanced Aircraft Design and Technologies
- Iron-based superconductors research
- Energy, Environment, Economic Growth
ETH Zurich
2014-2024
TU Wien
2023
University of Stuttgart
2006-2021
IAC (United States)
2020
University of Vienna
2008-2016
Board of the Swiss Federal Institutes of Technology
2016
Goethe University Frankfurt
1989-1994
Abstract. Within the framework of AeroCom (Aerosol Comparisons between Observations and Models) initiative, state-of-the-art modelling aerosol optical properties is assessed from 14 global models participating in phase III control experiment (AP3). The are similar to CMIP6/AerChemMIP Earth System Models (ESMs) provide a robust multi-model ensemble. Inter-model spread species lifetimes emissions appears be that mass extinction coefficients (MECs), suggesting depth (AOD) uncertainties...
Abstract. Poor air quality is currently responsible for large impacts on human health across the world. In addition, pollutants ozone (O3) and particulate matter less than 2.5 µm in diameter (PM2.5) are also radiatively active atmosphere can influence Earth's climate. It important to understand effect of climate mitigation measures over historical period different future scenarios ascertain any from both health. The Coupled Model Intercomparison Project Phase 6 (CMIP6) presents an...
Abstract. We introduce and evaluate aerosol simulations with the global aerosol–climate model ECHAM6.3–HAM2.3, which is component of fully coupled aerosol–chemistry–climate ECHAM–HAMMOZ. Both host atmospheric climate ECHAM6.3 HAM2.3 were updated from previous versions. The version HAM contains improved parameterizations processes such as cloud activation, well emission fields for anthropogenic species modifications in online computation sea salt mineral dust emissions. Aerosol results nudged...
A large number of processes are involved in the chain from emissions aerosol precursor gases and primary particles to impacts on cloud radiative forcing. Those manifest a relationships that can be expressed as factors dlnX/dlnY driving effects These include between condensation nuclei (CCN) concentration emissions, droplet CCN concentration, fraction number, optical depth forcing depth. The relationship further decomposed into sum two terms involving effective radius liquid water path with...
Significance Uncertainties in the strength of aerosol–cloud interactions drive current uncertainty anthropogenic forcing climate. Previous studies have highlighted shortcomings using satellite data for determining forcing, which underestimate aerosol forcing. This work demonstrates that component radiative from due to instantaneous effect on cloud reflectivity (RFaci) can be calculated within 20%, only present-day observations variability and properties, provided is known. The model results...
Abstract. Nudging as an assimilation technique has seen increased use in recent years the development and evaluation of climate models. Constraining simulated wind temperature fields using global weather reanalysis facilitates more straightforward comparison between simulation observation, reduces uncertainties associated with natural variabilities large-scale circulation. On other hand, forcing introduced by nudging can be strong enough to change basic characteristics model climate. In...
Abstract. A total of 16 global chemistry transport models and general circulation have participated in this study; 14 been evaluated with regard to their ability reproduce the near-surface observed number concentration aerosol particles cloud condensation nuclei (CCN), as well derived droplet (CDNC). Model results for period 2011–2015 are compared measurements (aerosol particle number, CCN composition submicron fraction) from nine surface stations located Europe Japan. The evaluation focuses...
Abstract. In this study we examine the performance of 31 global model radiative transfer schemes in cloud-free conditions with prescribed gaseous absorbers and no aerosols (Rayleigh atmosphere), scattering-only aerosols, more absorbing aerosols. Results are compared to benchmark results from high-resolution, multi-angular line-by-line radiation models. For purely scattering bias relative models top-of-the atmosphere aerosol forcing ranges roughly −10 20%, over- underestimates cooling at...
We measured the optical reflectivity of [001]-oriented $n$-doped ${\mathrm{Cd}}_{3}{\mathrm{As}}_{2}$ in a broad frequency range (50--22 000 ${\mathrm{cm}}^{\ensuremath{-}1}$) for temperatures from 10 to 300 K. The conductivity, $\ensuremath{\sigma}(\ensuremath{\omega})={\ensuremath{\sigma}}_{1}(\ensuremath{\omega})+\mathrm{i}{\ensuremath{\sigma}}_{2}(\ensuremath{\omega})$, is isotropic within (001) plane; its real part follows power law,...
Abstract. The global aerosol–climate model ECHAM6.3–HAM2.3 (E63H23) as well the previous versions ECHAM5.5–HAM2.0 (E55H20) and ECHAM6.1–HAM2.2 (E61H22) are evaluated using observational datasets for clouds precipitation. In E63H23, amount of low clouds, liquid ice water path, cloud radiative effects more realistic than in versions. E63H23 has a physically based aerosol activation scheme, improvements cover changes detrainment convective sticking efficiency accretion crystals by snow,...
Abstract. The chemistry–climate model ECHAM-HAMMOZ contains a detailed representation of tropospheric and stratospheric reactive chemistry state-of-the-art parameterizations aerosols using either modal scheme (M7) or bin (SALSA). This article describes evaluates the version ECHAM6.3-HAM2.3-MOZ1.0 with focus on gas-phase chemistry. A 10-year simulation was performed to test stability provide data for its evaluation. comparison observations concentrates year 2008 includes total column ozone CO...
Abstract. Increased concentrations of aerosol can enhance the albedo warm low-level cloud. Accurately quantifying this relationship from space is challenging due in part to contamination statistics near clouds. Aerosol retrievals clouds be influenced by stray cloud particles areas assumed cloud-free, particle swelling humidification, shadows and enhanced scattering into field (3-D radiative transfer) To screen for we have developed a new cloud–aerosol pairing algorithm (CAPA) link...
Abstract. In this paper, we present the implementation and evaluation of aerosol microphysics module SALSA2.0 in framework aerosol–chemistry–climate model ECHAM-HAMMOZ. It is an alternative to default modal scheme M7 The within ECHAM-HAMMOZ evaluated against observations optical properties, mass, size distributions, comparing also skill implementation. largest differences between are methods used for calculating microphysical processes, i.e., nucleation, condensation, coagulation, hydration....
Cirrus clouds impact the planetary energy balance and upper-tropospheric water vapor transport are therefore relevant for climate. In this study cirrus at temperatures colder than −40°C simulated by ECHAM–Hamburg Aerosol Module (ECHAM-HAM) general circulation model compared to Cloud–Aerosol Lidar Infrared Pathfinder Satellite Observations ( CALIPSO) satellite data. The captures cloud cover pattern reproduces observed median ice content within a factor of 2, while extinction is overestimated...
Abstract. How clouds change in a warmer climate remains one of the largest uncertainties for equilibrium sensitivity (ECS). While large spread cloud feedback arises from low-level clouds, it was recently shown that mixed-phase are also important ECS. If current contain too few supercooled droplets, much ice will to liquid water climate. As by Tan et al. (2016), this overestimates negative cloud-phase and underestimates ECS CAM global model (GCM). Here we use newest version ECHAM6-HAM2 GCM...
Abstract. This study presents a multiparameter analysis of aerosol trends over the last 2 decades at regional and global scales. Regional time series have been computed for set nine optical, chemical-composition mass properties by using observations from several ground-based networks. From these derived different regions world. Most related to loading exhibit negative trends, both surface in total atmospheric column. Significant decreases optical depth (AOD) are found Europe, North America,...
Abstract. The radiative forcing from aerosols (particularly through their interaction with clouds) remains one of the most uncertain components human climate. Observation-based studies have typically found a smaller aerosol effective than in model simulations and were given preferential weighting Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). With own sources uncertainty, it is not clear that observation-based estimates are more reliable. Understanding source...
Observations of cloud processes can reduce aerosol forcing uncertainty by constraining parameterizations in climate models.
The climate models of the Intergovernmental Panel on Climate Change list black carbon (BC) as an important contributor to global warming based its radiative forcing (RF) impact. Examining closely these models, it becomes apparent that they might underpredict significantly direct RF for BC, largely due their assumed spherical BC morphology. Specifically, light absorption and agglomerates are enhanced by scattering between constituent primary particles determined Rayleigh-Debye-Gans theory...
Abstract. General circulation models' (GCMs) estimates of the liquid water path adjustment to anthropogenic aerosol emissions differ in sign from other lines evidence. This reduces confidence effective radiative forcing climate by aerosol–cloud interactions (ERFaci). The discrepancy is thought stem part GCMs' inability represent turbulence–microphysics cloud-top entrainment, a mechanism that leads reduction response an increase aerosols. In real atmosphere, enhanced entrainment be dominant...
Abstract. General circulation models' (GCMs) estimates of the liquid water path adjustment to anthropogenic aerosol emissions differ in sign from other lines evidence. This reduces confidence effective radiative forcing climate by aerosol–cloud interactions (ERFaci). The discrepancy is thought stem part GCMs' inability represent turbulence–microphysics cloud-top entrainment, a mechanism that leads reduction response an increase aerosols. In real atmosphere, enhanced entrainment be dominant...
Utilizing infrared vibrational spectroscopy we have investigated dimerized two-dimensional organic salts in order to search for possible charge redistribution that might constitute electronic dipoles and ferroelectricity: the quantum spin liquid $\ensuremath{\kappa}$-(BEDT-TTF)${}_{2}$Cu${}_{2}$(CN)${}_{3}$ [BEDT-TTF: bis-(ethylenedithio)tetrathiafulvalene], antiferromagnetic Mott insulator $\ensuremath{\kappa}$-(BEDT-TTF)${}_{2}$Cu[N(CN)${}_{2}$]Cl, superconductor...
Abstract. Aerosol–cloud interactions continue to constitute a major source of uncertainty for the estimate climate radiative forcing. The variation aerosol indirect effects (AIE) in models is investigated across different dynamical regimes, determined by monthly mean 500 hPa vertical pressure velocity (ω500), lower-tropospheric stability (LTS) and large-scale surface precipitation rate derived from several global (GCMs), with focus on liquid water path (LWP) response cloud condensation...