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  1. Conference proceedings ; Online: The impact of dynamical downscaling in different pollutant transport scenarios

    Poulidis, A. / Meyer, S. / Schlager, H. / Vrekoussis, M.

    XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)

    2023  

    Abstract: Pollutant transport modelling is widely used to study and forecast pollution events. Regional scale models are often employed to produce high-resolution datasets to drive transport modelling; however, this requires expertise, resources, and time. As such, ...

    Abstract Pollutant transport modelling is widely used to study and forecast pollution events. Regional scale models are often employed to produce high-resolution datasets to drive transport modelling; however, this requires expertise, resources, and time. As such, the benefits of downscaling under different transport scenarios need to be explored. Here, the added value of downscaling was tested in the aftermath of the “Effect of Megacities on the transport and transformation of pollutants on the regional to global scales” (EMeRGe) project. During the project, transport forecasts were carried out after controlled releases of perfluoroalkylcycloalkanes (PFCs) to identify sampling areas for aircraft observations using IFS forecast data for 3 cases over different orographic settings: short-distance transport over small-scale topographic maxima (Manilla; Philippines), short-distance transport over large-scale topographic maxima (Taipei, Taiwan) and long-distance transport over mixed topography (Nanjing, China, sampled over Taiwan). Considering the expected PFC mixing ratios of ppqV, it is important to explore whether the best possible areas were chosen. To do this, transport simulations were repeated using: FLEXPART (with ERA5 and IFS data), and FLEXPART-WRF (with dynamically-downscaled IFS data down to 1.1km and 4 PBL parametrisations. Of the three scenarios, dynamical downscaling led to significant differences for the Manilla and Taipei cases, caused by the representation of the orographic flow regimes. The choice of PBL scheme also significantly impacted accuracy, but there was no systematically better-performing option. Overall, results highlight the role that dynamical downscaling can play as an important component in campaign planning when dealing with observations over orographically-complex areas.
    Subject code 380
    Language English
    Publishing date 2023-07-11
    Publishing country de
    Document type Conference proceedings ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Conference proceedings ; Online: An unsupervised machine learning-based methodology to study the seasonal dispersal pathways of short-lived pollutants from Major Population Centers

    Poulidis, A. / Daskalakis, N. / Kanakidou, M. / Vrekoussis, M.

    XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)

    2023  

    Abstract: The rapid increase in human population since 1900 has occurred along with a rapid increase in urbanization - the process of migration from rural into urban areas. The fossil fuel combustion-based emissions affecting areas with high population densities ... ...

    Abstract The rapid increase in human population since 1900 has occurred along with a rapid increase in urbanization - the process of migration from rural into urban areas. The fossil fuel combustion-based emissions affecting areas with high population densities induce a significant health risk for local populations. Protection of human health requires better knowledge of local and regional impacts of urban pollution dispersal. This study addresses the issue of short-lived pollutant transport (e.g. NOx) by constructing a methodology to study the seasonality of common dispersal pathways from Major Population Centers (MPCs); initially applied to 5 MPCs in south America during 2018. For each city, ERA5 reanalysis data were used to drive the FLEXPART emission transport model to simulate the dispersal of near-surface emissions. Simulations are performed for a total of 8 hours from release in the early morning and in the evening, to capture the effects of commuting. A total of 100,000 trajectories per release time per city were analyzed to create representative average trajectories. The k-means clustering algorithm was then applied to categorize the emissions per MPC. Clustering for each MPC led to a robust grouping of trajectories that were seen to reflect climatological and topographic phenomena during the simulation period and exhibit strong seasonality. This finding supports potential applicability of the proposed methodology for a global analysis of MPC emissions.
    Subject code 910
    Language English
    Publishing date 2023-07-11
    Publishing country de
    Document type Conference proceedings ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Conference proceedings ; Online: A multi-model study on the impacts of continuous volcanic activity on air quality in the surrounding communities

    Poulidis, A. / Takishita, K. / Iguchi, M. / Vrekoussis, M.

    XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)

    2023  

    Abstract: Chemistry modelling can be employed to study regional air quality and inform mitigation strategies. To accurately represent air quality, realistic emission data for all natural and anthropogenic sources need to be supplied. Volcanic emissions represent a ...

    Abstract Chemistry modelling can be employed to study regional air quality and inform mitigation strategies. To accurately represent air quality, realistic emission data for all natural and anthropogenic sources need to be supplied. Volcanic emissions represent a significant challenge, due to their unpredictable nature. As a result, only a small number of volcanoes are included in emission datasets, focusing only SO 2 , despite the potential release of micron-scale volcanic ash that can affect particulate matter (PM) concentrations. These emissions can be especially important in the case of volcanoes with long periods of passive emissions and intermittent eruptions, as in the case of Sakurajima volcano in southern Japan. Due to its high level of activity since 1955 and the large nearby population, Sakurajima is one of the most closely-monitored volcanoes in the world. The permanent deployment of equipment such as tiltmeters and tephra collectors has allowed for the accurate estimation of volcanic ash emissions, giving us the unique opportunity to provide realistic input data for air quality modelling. Emissions were simulated using two models: WRF-chem, a chemistry model, and FALL3D a volcanic emission transport model. Simulations are carried out for 2019, covering anthropogenic, biomass burning and non-volcanogenic natural emissions (WRF-chem) and volcanic emissions (FALL3D), with results validated against daily surface observations of airborne concentrations (PM and SO 2 ) and monthly ashfall values within the Kagoshima prefecture. Overall, results provide the first direct comparison of the ratio between volcanogenic and non-volcanogenic emissions and confirm the importance of the former.
    Subject code 550
    Language English
    Publishing date 2023-07-11
    Publishing country de
    Document type Conference proceedings ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: New insights into real-time detection of tephra grainsize, settling velocity and sedimentation rate.

    Freret-Lorgeril, V / Bonadonna, C / Rossi, E / Poulidis, A P / Iguchi, M

    Scientific reports

    2022  Volume 12, Issue 1, Page(s) 4650

    Abstract: Characterizing the size and settling velocity of pyroclastic fragments injected into the atmosphere during volcanic eruptions (i.e., tephra) is crucial to the forecasting of plume and cloud dispersal. Optical disdrometers have been integrated into ... ...

    Abstract Characterizing the size and settling velocity of pyroclastic fragments injected into the atmosphere during volcanic eruptions (i.e., tephra) is crucial to the forecasting of plume and cloud dispersal. Optical disdrometers have been integrated into volcano monitoring networks worldwide in order to best constrain these parameters in real time. Nonetheless, their accuracy during tephra fallout still needs to be assessed. A significant complication is the occurrence of particle aggregates that modify size and velocity distributions of falling tephra. We made the first use of the Thies Clima Laser Precipitation Monitor (LPM) for tephra-fallout detection at Sakurajima volcano (Japan), which is characterized by a lower size detection window with respect to more commonly used disdrometers (e.g., Parsivel
    MeSH term(s) Atmosphere ; Disasters ; Japan ; Volcanic Eruptions
    Language English
    Publishing date 2022-03-17
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-022-08711-1
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: The Effect of Wind and Atmospheric Stability on the Morphology of Volcanic Plumes From Vulcanian Eruptions

    Poulidis, A. P. / Takemi, T. / Iguchi, M.

    Journal of geophysical research. 2019 Aug., v. 124, no. 8

    2019  

    Abstract: Volcanic plumes from small and moderate eruptions represent a challenge in the study of plume morphology due to eruption source parameter uncertainties and atmospheric influence. Sakurajima volcano, Japan, features such activity and due to its continuous ...

    Abstract Volcanic plumes from small and moderate eruptions represent a challenge in the study of plume morphology due to eruption source parameter uncertainties and atmospheric influence. Sakurajima volcano, Japan, features such activity and due to its continuous eruptions in the recent years provides an ideal natural laboratory. A data set of 896 eruptions between 2009 and 2016 with well‐constrained plume heights, estimated erupted mass, and associated atmospheric conditions has been compiled. Plume heights ranged between 1,500 and 5,000 m and mainly developed under stable atmospheric stratification and low background wind speeds. The eruptions presented in the database were used to drive FPLUME, a 1‐D integral volcanic plume model, to study the simulated plume morphology. FPLUME was seen to provide consistent results under stable atmospheric stratification. A method for the real‐time monitoring of erupted mass used in the Sakurajima observatory was seen to provide appropriate first guess estimates for the eruptions, showing agreement with analytical and simulated mass flow rate calculations. Volcanic plumes from Sakurajima show significant influence by the atmospheric environment. The plume scaling parameter (Π) was used to characterize the expected degree of plume bending with results correlating well against modeled plume angles. The vertical wind profile was seen to have a significant impact on the resolved plume. Wind shear characteristics were seen to have a mechanical effect on the plume, aiding or inhibiting bending. Finally, potential issues were identified in simulations under unstable atmospheric conditions as the model either failed to provide a solution or overestimated the plume height.
    Keywords Japan ; data collection ; databases ; geophysics ; mass flow ; models ; research ; wind
    Language English
    Dates of publication 2019-08
    Size p. 8013-8029.
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ISSN 2169-9313
    DOI 10.1029/2018JB016958
    Database NAL-Catalogue (AGRICOLA)

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  6. Article ; Online: Aerodynamic characteristics and genesis of aggregates at Sakurajima Volcano, Japan.

    Vecino, M C Diaz / Rossi, E / Freret-Lorgeril, V / Fries, A / Gabellini, P / Lemus, J / Pollastri, S / Poulidis, A P / Iguchi, M / Bonadonna, C

    Scientific reports

    2022  Volume 12, Issue 1, Page(s) 2044

    Abstract: Aggregation of volcanic ash is known to significantly impact sedimentation from volcanic plumes. The study of particle aggregates during tephra fallout is crucial to increase our understanding of both ash aggregation and sedimentation. In this work, we ... ...

    Abstract Aggregation of volcanic ash is known to significantly impact sedimentation from volcanic plumes. The study of particle aggregates during tephra fallout is crucial to increase our understanding of both ash aggregation and sedimentation. In this work, we describe key features of ash aggregates and ash sedimentation associated with eleven Vulcanian explosions at Sakurajima Volcano (Japan) based on state-of-the-art sampling techniques. We identified five types of aggregates of both Particle Cluster (PC) and Accretionary Pellet (AP) categories. In particular, we found that PCs and the first and third type of APs can coexist within the same eruption in rainy conditions. We also found that the aerodynamic properties of aggregates (e.g., terminal velocity and density) depend on their type. In addition, grainsize analysis revealed that characteristics of the grainsize distributions (GSDs) of tephra samples correlate with the typology of the aggregates identified. In fact, bimodal GSDs correlate with the presence of cored clusters (PC3) and liquid pellets (AP3), while unimodal GSDs correlate either with the occurrence of ash clusters (PC1) or with the large particles (coarse ash) coated by fine ash (PC2).
    Language English
    Publishing date 2022-02-07
    Publishing country England
    Document type Journal Article
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-022-05854-z
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Book ; Thesis: Die Entwicklung und Situation der Grundschullehrerausbildung in Griechenland

    Poulidis, Alexandros

    1986  

    Author's details vorgelegt von Alexandros Poulidis
    Language German
    Size IV, 350 S., graph. Darst.
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Frankfurt am Main, 1986
    Database Former special subject collection: coastal and deep sea fishing

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