Peter Huszar

Bio: Peter Huszar is an academic researcher from Charles University in Prague. The author has contributed to research in topics: Weather Research and Forecasting Model & Climate model. The author has an hindex of 13, co-authored 41 publications receiving 483 citations. Previous affiliations of Peter Huszar include Centre national de la recherche scientifique.

Modeling the regional impact of ship emissions on NO x and ozone levels over the Eastern Atlantic and Western Europe using ship plume parameterization

Abstract: . In general, regional and global chemistry transport models apply instantaneous mixing of emissions into the model's finest resolved scale. In case of a concentrated source, this could result in erroneous calculation of the evolution of both primary and secondary chemical species. Several studies discussed this issue in connection with emissions from ships and aircraft. In this study, we present an approach to deal with the non-linear effects during dispersion of NOx emissions from ships. It represents an adaptation of the original approach developed for aircraft NOx emissions, which uses an exhaust tracer to trace the amount of the emitted species in the plume and applies an effective reaction rate for the ozone production/destruction during the plume's dilution into the background air. In accordance with previous studies examining the impact of international shipping on the composition of the troposphere, we found that the contribution of ship induced surface NOx to the total reaches 90% over remote ocean and makes 10–30% near coastal regions. Due to ship emissions, surface ozone increases by up to 4–6 ppbv making 10% contribution to the surface ozone budget. When applying the ship plume parameterization, we show that the large scale NOx decreases and the ship NOx contribution is reduced by up to 20–25%. A similar decrease was found in the case of O3. The plume parameterization suppressed the ship induced ozone production by 15–30% over large areas of the studied region. To evaluate the presented parameterization, nitrogen monoxide measurements over the English Channel were compared with modeled values and it was found that after activating the parameterization the model accuracy increases.

Modelling the effects of climate change on air quality over Central and Eastern Europe: concept, evaluation and projections

Abstract: Modelling the effects of climate change on air quality over Central and Eastern Europe: concept, evaluation and projections Katarzyna Juda-Rezler, Magdalena Reizer, Peter Huszar, Bernd C. Kruger, Prodromos Zanis, Dimiter Syrakov, Eleni Katragkou, Wojciech Trapp, Dimitris Melas, Hristo Chervenkov, Ioannis Tegoulias, Tomas Halenka 1Faculty of Environmental Engineering, Warsaw University of Technology, 00-653 Warsaw, Poland 2Department of Meteorology and Environment Protection, Charles University, 180 00 Prague, Czech Republic 3Institute of Meteorology, University of Natural Resources and Life Sciences, 1190 Vienna, Austria 4Department of Meteorology and Climatology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece 5Department of Air and Water Pollution, National Institute of Meteorology and Hydrology, 1784 Sofia, Bulgaria 6Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece 7Air Protection Unit of Ekometria, 80-299 Gdansk, Poland 8National Institute of Meteorology and Hydrology, Branch Plovdiv, 4000 Plovdiv, Bulgaria

Decadal regional air quality simulations over Europe in present climate: near surface ozone sensitivity to external meteorological forcing

Abstract: . Regional climate-air quality decadal simulations over Europe were carried out with the RegCM3/CAMx modeling system for the time slice 1991–2000, in order to study the impact of different meteorological forcing on surface ozone. The RegCM3 regional climate model was firstly constrained by the ERA40 reanalysis dataset which is considered as an experiment with perfect meteorological boundary conditions and then it was constrained by the global circulation model ECHAM5. A number of meteorological parameters were examined including the 500 mb geopotential height, solar radiation, temperature, cloud liquid water path, planetary boundary layer height and surface wind. The different RegCM meteorological forcing resulted in changes of near surface ozone over Europe ranging between ± 4 ppb for winter and summer. The area showing the greatest sensitivity in O3 during winter is central and southern Europe while in summer central north continental Europe. The different meteorological forcing impacts on the atmospheric circulation, which in turn affects cloudiness and solar radiation, temperature, wind patterns and the meteorology depended biogenic emissions. For comparison reasons, the impact of chemical boundary conditions on surface ozone was additionally examined with a series of sensitivity studies, indicating that surface ozone changes are comparable to those caused by the different meteorological forcing. These findings suggest that, when it comes to regional climate-air quality simulations, the selection of external meteorological forcing can be as important as the selection of adequate chemical lateral boundary conditions.

Regional climate model assessment of the urban land-surface forcing over central Europe

Abstract: For the purpose of qualifying and quantifying the climate impact of cities and urban surfaces in general on climate of central Europe, the surface parameterization in regional climate model RegCM4 has been extended with the Single-layer Urban Canopy Model (SLUCM). A set of experiments was performed over the period of 2005–2009 for central Europe, either without considering urban surfaces or with the SLUCM treatment. Results show a statistically significant impact of urbanized surfaces on temperature (up to 1.5 K increase in summer) as well as on the boundary layer height (increases up to 50 m). Urbanization further influences surface wind with a winter decrease up to −0.6 m s−1, though both increases and decreases were detected in summer depending on the location relative to the cities and daytime (changes up to 0.3 m s−1). Urban surfaces significantly reduce the humidity over the surface. This impacts the simulated summer precipitation rate, showing a decrease over cities of up to −2 mm day−1. Significant temperature increases are simulated over higher altitudes as well, not only within the urban canopy layer. With the urban parameterization, the climate model better describes the diurnal temperature variation, reducing the cold afternoon and evening bias of RegCM4. Sensitivity experiments were carried out to quantify the response of the meteorological conditions to changes in the parameters specific to the urban environment, such as street width, building height, albedo of the roofs and anthropogenic heat release. The results proved to be rather robust and the choice of the key SLUCM parameters impacts them only slightly (mainly temperature, boundary layer height and wind velocity). Statistically significant impacts are modelled not only over large urbanized areas, but the influence of the cities is also evident over rural areas without major urban surfaces. It is shown that this is the result of the combined effect of the distant influence of the cities and the influence of the minor local urban surface coverage.

Effects of climate change on ozone and ­particulate matter over Central and Eastern Europe

Abstract: We investigated the changes in exceedances of key atmospheric pollutants due to climate change in central and southeastern Europe. The RegCM3/CAMx and ALADINCLIMATE/CMAQ regional climate-chemistry modelling systems were used for high-resolution simulations (10 km). The simulations performed cover 3 decadal time slices (1991−2000, 2041−2050, 2091−2100). The future simulations were driven under the A1B IPCC scenario. Our model simulations yielded changes in ozone, particulate matter with a diameter <10 μm (PM10) and sulphur dioxide (SO2) resulting from climate change, without taking into consideration changes in anthropogenic emissions. We observed a shift in the average pollutant levels, and the frequency of occurrence of extreme pollution changed, especially in 2091–2100. Due to elevated air temperature, accumulated ozone exposure over the 40 ppbv (parts per billion by volume) threshold (AOT40) for crops and forests tended to increase by up to 20 to 30% in many areas of central Europe by the end of the century. Marked increases in the number of 8 h ozone threshold exceedances and ozone maxima were also observed. An increase in hourly and daily SO2 exceedances was predicted. Finally, PM10 exceedances were predicted to change due to different future climate. A small change (±1 d yr−1) was calculated for an extensive area of central Europe, and exceedances decreased around the Benelux states and Romania. The modelled SO2 and PM10 changes can be partly attributed to different horizontal and vertical mixing as evidenced by changes in the ventilation co efficient (defined as the product of horizontal wind speed at the surface and the planetary boundary layer height), and the majority of the SO2 and PM10 exceedances occurred during winter and autumn.

State-of-the-art with regional climate models

Abstract: Regional climate models are used by a large number of groups, for more or less all regions of the world. Regional climate models are complementary to global climate models. A typical use of regional climate models is to add further detail to global climate analyses or simulations, or to study climate processes in more detail than global models allow. The relationship between global and regional climate models is much akin to that of global and regional weather forecasting models. Over the past 20 years, the development of regional climate models has led to increased resolution, longer model runs, and steps towards regional climate system models. During recent years, community efforts have started to emerge in earnest, which can be expected to further advance the state-of-the-art in regional climate modeling. Applications of regional climate models span both the past and possible future climates, facilitating climate impact studies, information and support to climate policy, and adaptation. (Less)

Global air quality and climate

Abstract: Emissions of air pollutants and their precursors determine regional air quality and can alter climate. Climate change can perturb the long-range transport, chemical processing, and local meteorology that influence air pollution. We review the implications of projected changes in methane (CH4), ozone precursors (O3), and aerosols for climate (expressed in terms of the radiative forcing metric or changes in global surface temperature) and hemispheric-to-continental scale air quality. Reducing the O3 precursor CH4 would slow near-term warming by decreasing both CH4 and tropospheric O3. Uncertainty remains as to the net climate forcing from anthropogenic nitrogen oxide (NOx) emissions, which increase tropospheric O3 (warming) but also increase aerosols and decrease CH4 (both cooling). Anthropogenic emissions of carbon monoxide (CO) and non-CH4 volatile organic compounds (NMVOC) warm by increasing both O3 and CH4. Radiative impacts from secondary organic aerosols (SOA) are poorly understood. Black carbon emission controls, by reducing the absorption of sunlight in the atmosphere and on snow and ice, have the potential to slow near-term warming, but uncertainties in coincident emissions of reflective (cooling) aerosols and poorly constrained cloud indirect effects confound robust estimates of net climate impacts. Reducing sulfate and nitrate aerosols would improve air quality and lessen interference with the hydrologic cycle, but lead to warming. A holistic and balanced view is thus needed to assess how air pollution controls influence climate; a first step towards this goal involves estimating net climate impacts from individual emission sectors. Modeling and observational analyses suggest a warming climate degrades air quality (increasing surface O3 and particulate matter) in many populated regions, including during pollution episodes. Prior Intergovernmental Panel on Climate Change (IPCC) scenarios (SRES) allowed unconstrained growth, whereas the Representative Concentration Pathway (RCP) scenarios assume uniformly an aggressive reduction, of air pollutant emissions. New estimates from the current generation of chemistry–climate models with RCP emissions thus project improved air quality over the next century relative to those using the IPCC SRES scenarios. These two sets of projections likely bracket possible futures. We find that uncertainty in emission-driven changes in air quality is generally greater than uncertainty in climate-driven changes. Confidence in air quality projections is limited by the reliability of anthropogenic emission trajectories and the uncertainties in regional climate responses, feedbacks with the terrestrial biosphere, and oxidation pathways affecting O3 and SOA.

A review of operational, regional-scale, chemical weather forecasting models in Europe

Abstract: Numerical models that combine weather forecasting and atmospheric chemistry are here referred to as chemical weather forecasting models. Eighteen operational chemical weather forecasting models on regional and continental scales in Europe are described and compared in this article. Topics discussed in this article include how weather forecasting and atmospheric chemistry models are integrated into chemical weather forecasting systems, how physical processes are incorporated into the models through parameterization schemes, how the model architecture affects the predicted variables, and how air chemistry and aerosol processes are formulated. In addition, we discuss sensitivity analysis and evaluation of the models, user operational requirements, such as model availability and documentation, and output availability and dissemination. In this manner, this article allows for the evaluation of the relative strengths and weaknesses of the various modelling systems and modelling approaches. Finally, this article highlights the most prominent gaps of knowledge for chemical weather forecasting models and suggests potential priorities for future research directions, for the following selected focus areas: emission inventories, the integration of numerical weather prediction and atmospheric chemical transport models, boundary conditions and nesting of models, data assimilation of the various chemical species, improved understanding and parameterization of physical processes, better evaluation of models against data and the construction of model ensembles. © 2012 Author(s).