Atmospheric Physics & Environmental Sciences

Johannes Gutenberg University Mainz > Faculty 08 > Physics > Physics Research > Research Areas > Atmospheric Physics & Environmental Sciences

Our research explores the dynamics of the Earth’s system with a focus on the atmosphere across scales, from local processes to the whole globe. We aim to improve the theoretical understanding of nonlinear phenomena and their interactions with physical processes, which is key for advancing weather forecasts and climate projections. Using numerical models, reanalysis data, and advanced diagnostic tools, we link theory with atmospheric observations and simulations. A central focus is on clouds, precipitation, aerosols, and atmospheric chemistry, studying how these factors interact to shape air quality, weather, and climate. By integrating dynamics, microphysics, and chemistry, we work toward a comprehensive framework that improves prediction and representation of uncertainties in climate and weather models.

The focus of our research is on the dynamics of the Earth‘s atmosphere from the micro scale all the way to the planetary scale. We aim to improve the conceptual understanding of the complex nonlinear dynamical phenomena and their interactions with „physical processes“. This understanding is essential to improve weather prediction and climate projections.

Our methods include a hierarchy of numerical models as well as the use of data from reanalysis projects and climate model simulations. As an important avenue towards conceptual understanding we develop and use sophisticated diagnostic tools allowing us to gain novel insight that cannot be obtained from just plotting model variables. The diagnostic tools, in turn, are related to theoretical concepts such as linear theory, PV thinking, or wave activity.

Our research team develops and applies computer models for the climate system which include atmospheric chemistry and its interactions with weather and climate. With the help of these tools we investigate how chemical compounds in the Earth system influence air quality and climate. It is key not only to simulate and analyse the distributions of relevant compounds in the system, but also to understand the processes which are responsible for the distributions of those trace species.
Our studies range from local and regional scales up to the entire Earth system, therefore including processes on a multitude of scales.

Clouds and precipitation are defining elements of weather and climate. Their occurrence is strongly determined by the dynamic forcing and thermodynamic conditions, but also by moisture and aerosol availability, and cloud microphysical processes. Clouds in turn influence the evolution of the atmospheric flow, thermodynamic conditions, and aerosol properties. Physical understanding of these complex interactions is a major challenge as is the representation of the moist atmosphere in operational weather forecasting and climate models. We are working on a fully integrated view of cloud microphysics, aerosol science, and atmospheric dynamics with particular foci on

comprehensive physical process understanding,
full integration of aspects from all three disciplines into field campaign planning, model evaluation, and the analysis of climate and weather data, and
representation of cloud microphysical / aerosol uncertainty in ensemble weather forecasting.

The research focuses on transport, transformation and mixing processes from the surface to the upper troposphere and lower stratosphere (UTLS). A focus in on the UTLS, where those processes strongly influence the distribution of radiatively active trace gases, aerosols and cirrus clouds. As all those compounds impact the radiative balance and hence surface temperatures, they are key to understanding climate change. The research combines airborne trace gas measurements, Lagrangian trajectory analysis, reanalysis data, and Earth system models to study cross-tropopause exchange, transport regimes, and pathways in the UTLS. Experimental work also investigates fundamental physical and chemical processes of aerosols, clouds, and hydrometeors using field campaigns and a vertical wind tunnel facility. A particular emphasis is also on aviation effects, which can significantly alter atmospheric composition and cloud properties, and are studied through an integrated approach linking aircraft and satellite observations, process studies, and model applications.

The central research topics of the group of Peter Hoor are related to transport and mixing processes affecting the tropopause region or the extratropical upper troposphere / lower stratosphere (ExUTLS, see e.g. Gettelman et al., 2011).

Changes of the distributions of trace gases, like water vapor, ozone and ozone depleting substances, and thin cirrus clouds in the upper troposphere and lower stratosphere (UTLS) strongly impact radiative forcing of the Earth’s climate and surface temperatures (Solomon et al., 2010), and are of key importance for understanding climate change (Hegglin and Shepherd, 2009; Riese et al., 2012). Transport and mixing in the extratropical upper troposphere / lower stratosphere (ExUTLS) play a key role for the quantitative understanding of the distribution of these radiatively active species (Riese et al., 2010). The formation of the extratropical transition layer (ExTL) around the tropopause, which exhibits chemical characteristics of both the stratosphere and the troposphere (Hoor et. al, 2002, 2004; Pan et al., 2004), is a direct consequence of the underlying frequent small scale mixing processes.

The AG Hoor combines airborne measurements of trace gases with Lagrangian analysis tools and meteorological analysis and reanalysis data as well as Earth system models to

investigate processes at the tropopause leading to cross tropopause exchange

to identify transport regimes and quantify time scales of transport in the UTLS region

identify transport pathways in the troposphere

The scientific activities for these topics are separated among different working groups. The key questions address fundamental physical and chemical processes concerning atmospheric aerosols, clouds, and large hydrometeors. The experimental research is centered on field measurements on various platforms. Additionally, detailed laboratory studies are conducted including the operation of the unique Mainz vertical wind tunnel facility.

Aircraft operating at cruise altitudes are the only direct anthropogenic emission sources in the tropopause region at altitudes of 8 to 12 km. Aviation contributes significanly to global warming through emissions of carbon dioxide, nitrogen oxides, aerosol and specifically through aircraft induced cloud modifications. At present, large uncertainties hinder the targetted reduction of individual climate effects from aviation. Clouds have a multifold impact on the atmosphere. They affect the radiation budget, take part in the hodrological cycle, offer sites for heterogeneous reactions and transport and redistribute trace gases. Particularly the ice nucleation processes, cloud life cycle and climate impact are not understood in detail.

The aim of the group is to study the effects of clouds on atmospheric composition and climate with a specific focus on aircraft emissions in a wholistic approach combining aircraft measurements, satellite observations, process studies and global modeling.