Papers by Johannes Werhahn
Describing the direct and indirect radiative effects of atmospheric aerosols over Europe by using coupled meteorology-chemistry simulations: a contribution from the AQMEII-Phase II exercise
dphase_mm5_15: MM5 model 72h forecast (15km) run by FZK-IMK for the MAP D-PHASE project
Project: D-PHASE, Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood... more Project: D-PHASE, Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood Events in the Alpine region - The Mesoscale Alpine Programme (MAP, the first WWRP Research and Development Project (RDP)) is an international research initiative devoted to the study of atmospheric and hydrological processes over mountainous terrain. It aims towards expanding our knowledge of weather and climate over complex topography, and thereby to improve current forecasting capabilities. A large-scale field phase in the Alpine region took place from 7 September to 15 November 1999. D-PHASE (Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood Events in the Alpine region) is a WWRP Forecast Demonstration Project (FDP) and aims at demonstrating some of the many achievements of MAP, in particular the ability of forecasting heavy precipitation and related flooding events in the Alpine region. The MAP FDP will address the entire forecasting chain ranging from ...
Atmospheric aerosols modify the radiative budget of the Earth due to their optical, microphysical... more Atmospheric aerosols modify the radiative budget of the Earth due to their optical, microphysical and chemical properties, and are considered one of the most uncertain climate forcing agents. In order to characterise the uncertainties associated with satellite and modelling approaches to represent aerosol optical properties, mainly aerosol optical depth (AOD) and Ångström exponent (AE), their representation by different remote-sensing sensors and regional online coupled chemistry-climate models over Europe are evaluated. This work also characterises whether the inclusion of aerosolradiation (ARI) or/and aerosol-cloud interactions (ACI) help improve the skills of modelling outputs. Two case studies were selected within the EuMetChem COST Action ES1004 framework when important aerosol episodes in 2010 all over Europe took place: a Russian wild-fire episode and a Saharan desert dust outbreak that covered most of the Mediterranean Sea. The model data came from different regional air-quality-climate simulations performed by working group 2 of EuMetChem, which differed according to whether ARI or ACI was included or not. The remotesensing data came from three different sensors: MODIS, OMI and SeaWIFS. The evaluation used classical statistical metrics to first compare satellite data versus the groundbased instrument network (AERONET) and then to evaluate model versus the observational data (both satellite and ground-based data). Regarding the uncertainty in the satellite representation of AOD, MODIS presented the best agreement with the AERONET observations compared to other satellite AOD observations. The differences found between remote-sensing Published by Copernicus Publications on behalf of the European Geosciences Union. 5022 L. Palacios-Peña et al.: An assessment of aerosol optical properties over Europe sensors highlighted the uncertainty in the observations, which have to be taken into account when evaluating models. When modelling results were considered, a common trend for underestimating high AOD levels was observed. For the AE, models tended to underestimate its variability, except when considering a sectional approach in the aerosol representation. The modelling results showed better skills when ARI+ACI interactions were included; hence this improvement in the representation of AOD (above 30 % in the model error) and AE (between 20 and 75 %) is important to provide a better description of aerosol-radiation-cloud interactions in regional climate models.
Improving the Representation of Flow in Complex Terrainby Regional-Local Scale Model Coupling
Development and Application of a Multi-scale Flow Field Analysis System for Complex Terrain
Hochaufgelöste Erfassung der urbanen Feinstaubbelastung mittels Messnetz aus kostengünstigen Sensoren und numerischen Simulationen
Gefahrstoffe Reinhaltung Der Luft, 2021
Im Rahmen des interdisziplinären Projekts „Smart Air Quality Network" (SmartAOnet) ist ein ... more Im Rahmen des interdisziplinären Projekts „Smart Air Quality Network" (SmartAOnet) ist ein Messsystem für die Erfassung und Visualisierung der räumlichen Verteilung von Luftschadstoffkonzentrationen im urbanen Raum entstanden. Die mehr als dreijährige Arbeit in SmartAOnet war darauf ausgerichtet, ein kostengünstiges Messnetz, das auf andere Städte übertragbar ist, mit Modellrechnungen (Stadtklimamodell PALM4U) zur hochaufgelösten -räumlichen und zeitlichen -Bestimmung der Luftqualität in der Modellregion Augsburg zu verknüpfen. Kernbestandteil ist ein Datenhaltungssystem auf der Projektwebseitewww.smartaq.net/en/dashboard/, das sowohl Daten der Konzentrationen von PM10, PM2,5 und Partikelanzahlen dieses Messnetzes als auch weiterer Luftschadstoff-und meteorologischer Messungen, der Verkehrszählschleifen und urbaner Charakteristika (unter anderem Gebäude-und Straßendaten) zusammenstellt und für jedermann zugänglich erfasst. Dasvielschichtige, heterogene Messnetz umfasst aktuell mehr als100 Middle-und Low-cost-Sensoren, zum Teil neu entwickeltestationäre Sensoren. Ergänzt wurden diese durch mobile Messungen (Fahrräder, Messkarren), unbemannte Flugobjekte undFernerkundungssysteme für die dreidimensionale Erfassungder Verteilung von Luftschadstoffen und meteorologischen Parametern auf einer Fläche von etwa 10 x 10 km, so dass bereitsmehrere hundert Millionen Datensätze erstellt werden konnten. Dazu hat auch die Bürgerbeteiligung durch Messungen mit Low-cost-Sensoren beigetragen
AGU Fall Meeting Abstracts, Dec 1, 2019
Global change has triggered several transformations, such as alterations in climate, land product... more Global change has triggered several transformations, such as alterations in climate, land productivity, water resources, and atmospheric chemistry, with far reaching impacts on ecosystem functions and services. Finding solutions to climate and land cover change-driven impacts on our terrestrial environment is one of the most important scientific challenges of the 21st century, with farreaching interlinkages to the socio-economy. The setup of the German Terrestrial Environmental Observatories (TERENO) Pre-Alpine Observatory was motivated by the fact that mountain areas, such as the pre-alpine region in southern Germany, have been exposed to more intense warming compared with the global average trend and to higher frequencies of extreme hydrological events, such as droughts and intense rainfall. Scientific research questions in the TERENO Pre-Alpine Observatory focus on improved process understanding and closing of combined energy, water, C, and N cycles at site to regional scales. The main long-term objectives of the TERENO Pre-Alpine Observatory include the characterization and quantification of climate change and land cover-management effects on terrestrial hydrology and biogeochemical processes at site and regional scales by joint measuring and modeling approaches. Here we present a detailed climatic and biogeophysical characterization of the TERENO Pre-Alpine Observatory and a summary of novel scientific findings from observations and projects. Finally, we reflect on future directions of climate impact research in this particularly vulnerable region of Germany.
Atmospheric Chemistry and Physics, Apr 12, 2018
Atmospheric aerosols modify the radiative budget of the Earth due to their optical, microphysical... more Atmospheric aerosols modify the radiative budget of the Earth due to their optical, microphysical and chemical properties, and are considered one of the most uncertain climate forcing agents. In order to characterise the uncertainties associated with satellite and modelling approaches to represent aerosol optical properties, mainly aerosol optical depth (AOD) and Ångström exponent (AE), their representation by different remote-sensing sensors and regional online coupled chemistry-climate models over Europe are evaluated. This work also characterises whether the inclusion of aerosolradiation (ARI) or/and aerosol-cloud interactions (ACI) help improve the skills of modelling outputs. Two case studies were selected within the EuMetChem COST Action ES1004 framework when important aerosol episodes in 2010 all over Europe took place: a Russian wild-fire episode and a Saharan desert dust outbreak that covered most of the Mediterranean Sea. The model data came from different regional air-quality-climate simulations performed by working group 2 of EuMetChem, which differed according to whether ARI or ACI was included or not. The remotesensing data came from three different sensors: MODIS, OMI and SeaWIFS. The evaluation used classical statistical metrics to first compare satellite data versus the groundbased instrument network (AERONET) and then to evaluate model versus the observational data (both satellite and ground-based data). Regarding the uncertainty in the satellite representation of AOD, MODIS presented the best agreement with the AERONET observations compared to other satellite AOD observations. The differences found between remote-sensing Published by Copernicus Publications on behalf of the European Geosciences Union. 5022 L. Palacios-Peña et al.: An assessment of aerosol optical properties over Europe sensors highlighted the uncertainty in the observations, which have to be taken into account when evaluating models. When modelling results were considered, a common trend for underestimating high AOD levels was observed. For the AE, models tended to underestimate its variability, except when considering a sectional approach in the aerosol representation. The modelling results showed better skills when ARI+ACI interactions were included; hence this improvement in the representation of AOD (above 30 % in the model error) and AE (between 20 and 75 %) is important to provide a better description of aerosol-radiation-cloud interactions in regional climate models.
Atmospheric Chemistry and Physics, Aug 11, 2017
The climate effect of atmospheric aerosols is associated with their influence on the radiative bu... more The climate effect of atmospheric aerosols is associated with their influence on the radiative budget of the Earth due to the direct aerosol-radiation interactions (ARIs) and indirect effects, resulting from aerosol-cloud-radiation interactions (ACIs). Online coupled meteorology-chemistry models permit the description of these effects on the basis of simulated atmospheric aerosol concentrations, although there is still some uncertainty associated with the use of these models. Thus, the objective of this work is to assess whether the inclusion of atmospheric aerosol radiative feedbacks of an ensemble of online coupled models improves the simulation results for maximum, mean and minimum temperature at 2 m over Europe. The evaluated models outputs originate from EuMetChem COST Action ES1004 simulations for Europe, differing in the inclusion (or omission) of ARI and ACI in the various models. The cases studies cover two important atmospheric aerosol episodes over Europe in the year 2010: (i) a heat wave event and a forest fire episode (July-August 2010) and (ii) a more humid episode including a Saharan desert dust outbreak in October 2010. The simulation results are evaluated against observational data from the E-OBS gridded database. The results indicate that, although there is only a slight improvement in the bias of the simulation results when including the radiative feedbacks, the spatiotemporal variability and correlation coefficients are improved for the cases under study when atmospheric aerosol radiative effects are included.
Smart Air Quality Network for spatial high-resolution monitoring in urban area
A pragmatic, data driven approach, which for the first time combines existing in situ and remote ... more A pragmatic, data driven approach, which for the first time combines existing in situ and remote sensing data sets with a networked mobile air pollutant measurement strategy in the urban space is an objective of the Smart Air Quality Network (SmartAQnet) project. It aims to implement an intelligent, reproducible, finely-tuned (spatial, temporal), yet cost-effective air quality measuring network, initially in the model region of Augsburg, Germany. Central to this is the development and utilization of partial, already existing (but not yet combined) data on the one hand and the collection and integration of relevant missing data on the other hand. Unmanned aerial vehicles (UAV) with low-weight meteorological sensors and particle counter are used to monitor the three-dimensional dynamics of the lower atmosphere. Ground-based remote sensing by ceilometer for mixing layer height detection as well as a Radio-Acoustic Sounding System (RASS) for temperature and wind profile measurements at the University campus complete the new network architecture and UAV height profiling of atmospheric parameters. The SmartAQnet research initiative focuses on the subject of data access and data-based applications. Such complex monitoring provides the basis of deeper process understanding of air pollution exposure. The network architecture is shown and first results about spatial variation of meteorological influences upon air pollution exposure is presented using ceilometer, UAV and the existing monitoring network data.
We present results of aircraft measurements which were performed using a 80 x 80 km^ box shaped f... more We present results of aircraft measurements which were performed using a 80 x 80 km^ box shaped flight path around the cities of Halle, Leipzig, and Bitterfeld, in the southern part of eastern Germany. The data sets, which were obtained close to emission sources of primary pollutants, are highly variable. The resulting skewed distributions make quantitative interpretation difficult. The influence of this region on regional air chemistry was detectable between 1990 and 1994. This is particularly true for SC>2 which is still emitted in large quantities both from point and area sources.
Measured mean global radiation (W/m 2) July 2006: RFB vs. observed July 2006 mean global radiatio... more Measured mean global radiation (W/m 2) July 2006: RFB vs. observed July 2006 mean global radiation Helmholtz Climate Initiative Regional Climate Change Topic 9
Contributions to the case studies Modeling protocol: Distributed to EuMetChem WG2/WG4 mailing lis... more Contributions to the case studies Modeling protocol: Distributed to EuMetChem WG2/WG4 mailing list members + 5 additional possible participants on June 24th.
Assessment of three-dimensional, fine-granular measurement of particulate matter by a smart air quality network in urban area
Remote Sensing of Clouds and the Atmosphere XXIV, 2019
Ground-based remote sensing by three ceilometers for mixing layer height detection over Augsburg ... more Ground-based remote sensing by three ceilometers for mixing layer height detection over Augsburg as well as a Radio- Acoustic Sounding System (RASS) for temperature and wind profile measurements at the campus of Augsburg University are applied together with UAV height profiling with low-weight meteorological sensors and particle counter to monitor the three-dimensional dynamics of the lower atmosphere. Results about meteorological influences upon spatial variation of air pollution exposure are presented on this data basis which is more than one year long. Special focus is on the information about atmospheric layering as well as mixing and transport conditions for emitted particulate matter. Better understanding of these complex processes support knowledge about quality of air, which we breath, and especially high air pollution episodes and hot spot pollution regions.
The TERENO-preAlpine Observatory: A Research Infrastructure for Hydrometeorological Observation and -Modeling across Compartments and Scales
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Papers by Johannes Werhahn