Sensitivity of Pollutant Concentrations to the Turbulence Schemes of a Dispersion Modelling Chain over Complex Orography

Atmospheric circulation over mountainous regions is more complex than over flat terrain due to the interaction of flows on various scales: synoptic-scale flows, thermally-driven mesoscale winds and turbulent fluxes. In order to faithfully reconstruct the circulation affecting the dispersion and deposition of pollutants in mountainous areas, meteorological models should have a sub-kilometer grid spacing, where turbulent motions are partially resolved and the parametrizations of the sub-grid scale fluxes need to be evaluated. In this study, a modelling chain based on the Weather Research and Forecasting (WRF) model and the chemical transport model Flexible Air Quality Regional Model (FARM) is applied to estimate the pollutant concentrations at a 0.5 km horizontal resolution over the Aosta Valley, a mountainous region of the northwestern Alps. Two pollution episodes that occurred in this region are reconstructed: one summer episode dominated by thermally-driven winds, and one winter episode dominated by synoptic-scale flows. Three WRF configurations with specific planetary boundary layer and surface layer schemes are tested, and the numerical results are compared with the surface measurements of meteorological variables at twenty-four stations. For each WRF configuration, two different FARM runs are performed, with turbulence-related quantities provided by the SURface-atmosphere interFace PROcessor or directly by WRF. The chemical concentrations resulting from the different FARM runs are compared with the surface measurements of particulate matter of less than 10 µm in diameter and nitrogen dioxide taken at five air quality stations. Furthermore, these results are compared with the outputs of the modelling chain employed routinely by the Aosta Valley Environmental Protection Agency, based on FARM driven by COSMO-I2 (COnsortium for Small-scale MOdelling) at 2.8 km horizontal grid spacing. The pollution events are underestimated by the modelling chain, but the bias between simulated and measured surface concentrations is reduced using the configuration based on WRF turbulence parametrizations, which imply a reduced dispersion

DUST GENERATION AND DISPERSION (PM10 AND PM2.5) IN THE AOSTA VALLEY: ANALYSIS WITH THE FARM MODEL

The aim of this work is to analyze the origin and the dispersion of the particulate matter (PM10 and PM2.5) in a mountainous region: the Aosta Valley. To meet this goal, different simulations were performed, using the flexible air quality regional model (FARM), to study two scenarios: winter and summer situations. To evaluate the performance of the FARM model in order to simulate the air quality situation of the selected periods, a comparison of modelled results against observed air quality data was carried out for both primary pollutants and particulate matter next to the measurement stations . Farm performed well in simulating especially ozone (O3) and nitrogen dioxide (NO2) concentrations, showing a good reproduction of both daily peaks and their daytime variations. PM model results revealed the tendency to under-predict the observed values, so we tried to use a different emission factor for the road traffic (Lohmeyer factor). The new results were good for the urban and suburban areas, but they give over-predictions close to highways. The PM characterisation provided by the model gives good results: in some different points of the analysis domain (mountain, plain and urban points) we found PM profiles wich reproduce expected values

Sensitivity of Pollutant Concentrations to the Turbulence Schemes of a Dispersion Modelling Chain over Complex Orography

Atmospheric circulation over mountainous regions is more complex than over flat terrain due to the interaction of flows on various scales: synoptic-scale flows, thermally-driven mesoscale winds and turbulent fluxes. In order to faithfully reconstruct the circulation affecting the dispersion and deposition of pollutants in mountainous areas, meteorological models should have a sub-kilometer grid spacing, where turbulent motions are partially resolved and the parametrizations of the sub-grid scale fluxes need to be evaluated. In this study, a modelling chain based on the Weather Research and Forecasting (WRF) model and the chemical transport model Flexible Air Quality Regional Model (FARM) is applied to estimate the pollutant concentrations at a 0.5 km horizontal resolution over the Aosta Valley, a mountainous region of the northwestern Alps. Two pollution episodes that occurred in this region are reconstructed: one summer episode dominated by thermally-driven winds, and one winter episode dominated by synoptic-scale flows. Three WRF configurations with specific planetary boundary layer and surface layer schemes are tested, and the numerical results are compared with the surface measurements of meteorological variables at twenty-four stations. For each WRF configuration, two different FARM runs are performed, with turbulence-related quantities provided by the SURface-atmosphere interFace PROcessor or directly by WRF. The chemical concentrations resulting from the different FARM runs are compared with the surface measurements of particulate matter of less than 10 µm in diameter and nitrogen dioxide taken at five air quality stations. Furthermore, these results are compared with the outputs of the modelling chain employed routinely by the Aosta Valley Environmental Protection Agency, based on FARM driven by COSMO-I2 (COnsortium for Small-scale MOdelling) at 2.8 km horizontal grid spacing. The pollution events are underestimated by the modelling chain, but the bias between simulated and measured surface concentrations is reduced using the configuration based on WRF turbulence parametrizations, which imply a reduced dispersion

Multi-year measurements of columnar aerosol properties at an Alpine EuroSkyRad Station

A Prede POM-02 sun/sky aerosol photometer has been operating in the Saint-Christophe (Aosta Valley, Italy) site for almost 4 years, measuring sun irradiance and sky diffuse radiance for retrieving columnar aerosol optical properties. The peculiar position in an Alpine valley makes this site particularly significant for both assessing aerosols radiative impact on the high-sensitivity mountain climate and for tracing long-range transport of aerosol within the Mediterranean basin, acting as a background station. Indeed, limited local aerosol sources make this site particularly suitable to study air masses advections and interactions in such a complex environment. Complying with the EuroSkyRad network procedures, the SUNRAD.pack and SKYRAD.pack inversion algorithms have been used to determine aerosol parameters from direct and diffuse radiative fluxes, respectively. The resulting aerosol optical depth (AOD) and Ångström exponent values generally show very low mean AOD values, but with a large standard deviation due to periodical advection phenomena from natural (e.g. Saharan dust) and anthropogenic (polluted air from Po Valley) sources, as resulting from both specific aerosol optical properties and HYSPLIT backward trajectories analysis. A co-located optical particle sizer (OPS) and a lidar-ceilometer, allow to assess both the particle size distribution (PSD) at the surface and the vertical aerosol distribution for some of the most significant advection episodes carrying aerosols from external sources to the valley

Air Quality in the Italian Northwestern Alps during Year 2020: Assessment of the COVID-19 «Lockdown Effect» from Multi-Technique Observations and Models

The effect of COVID-19 confinement regulations on air quality in the northwestern Alps is assessed here based on measurements at five valley sites in different environmental contexts. Surface concentrations of nitrogen oxides (NO and NO2), ozone (O3), particulate matter (PM2.5 and PM10), together with a thorough microphysical (size), chemical, and optical (light absorption) aerosol characterisation, complemented by observations along the vertical column are considered. Even in the relatively pristine environment of the Alps, the «lockdown effect» is well discernible, both in the early confinement phase and in late 2020. The variations observed during the first confinement period in the city of Aosta (−61% NO, −43% NO2, +5% O3, +9% PM2.5, −12% PM10, relative to average 2015–2019 conditions) are attributed to the competing effects of air pollution lockdown-induced changes (−74%, −52%, +18%, −13%, −27%, relative to the counterfactual scenario for 2020 provided by a predictive statistical model trained on past measurements) and meteorology (+52%, +18%, −11%, +25%, +20%, relative to average conditions). These changes agree well with the ones obtained from a chemical transport model with modified emissions according to the restrictions. With regard to column-integrated quantities and vertical profiles, the NO2 column density decreases by >20% due to the lockdown, whereas tropospheric aerosols are mainly influenced by large-scale dynamics (transport of secondary particles from the Po basin and mineral dust from the Sahara desert and the Caspian Sea), except a shallow layer about 500 m thick close to the surface, possibly sensitive to curtailed emissions (especially exhaust and non-exhaust particles from road traffic and fugitive emissions from the industry)

Risk factor analysis of posterior reversible encephalopathy syndrome after allogeneic hematopoietic SCT in children

no abstract availabl

Acute childhood idiopathic thrombocytopenic purpura: AIEOP consensus guidelines for diagnosis and treatment

Background and Objectives. A recent evaluation carried out by the Associazione Italiana di Ematologia e Oncologia Pediatrica (AIEOP) about practice management of acute childhood idiopathic thrombocytopenic purpura (ITP) revealed a remarkable difference of behaviors among the different AIEOP centers. A need for common practice guidelines for this frequent illness arose from this observation. Our aim was to make the diagnosis and treatment of childhood ITP uniform. In the future we will evaluate the influence of these guidelines on practice behaviors. Data sources and Methods. Our main reference was the 1996 document produced by the American Society of Hematology (ASH). Their recommendations were updated with information from literature searched for in the MEDLINE database (June 1996-October 1998); search terms included: thrombocytopenia, ITP, diagnosis, therapy, children. The computerized search retrieved 83 articles. Data extraction: the scientific validity of the literature was evaluated by a panel of members using published guidelines. The strength of the evidence was assessed using level of evidence criteria. Only data from level I and level II studies were taken in account. Only one study out of the 83 retrieved articles met these selection criteria and it was considered in addition to the 11 out of 581 articles selected in the ASH ITP guidelines. This preliminary work pointed out each issue about ITP not addressed by clinical studies and all participants in a Consensus Conference expressed their opinion about these issues. Results. Diagnosis is essentially based on history, physical examination, a complete blood count and an examination of the peripheral blood smear. Treatment is recommended taking into account the clinical picture and number of platelets. The main difference between these guidelines and those from ASH are: AIEOP guidelines rely on the opinion of the members of the consensus conference, ASH ones on a panel of experts; therapeutic options include only products available in Italy; the indications to treatment rely more on clinical picture than on platelet number. Interpretation and Conclusions.These are explicitly developed, evidence-based practice guidelines to assist Italian pediatricians in making decisions about diagnosis and appropriate health care for patients with acute childhood ITP

Pediatric immune thrombocytopenia: a focus on eltrombopag as second-line therapy

ABSTRACTBackground Immune thrombocytopenia (ITP) is the most common acquired bleeding disorder. In both children and adults, the primary goal of any therapeutic approach consists of cessation of bleeding and its prevention. Several options are currently available for first-line therapy in Europe, including corticosteroids and intravenous immunoglobulin (IVIg) infusion, which has a similar efficacy and safety profile in both the pediatric and adult populations. When second-line therapy is needed in the pediatric setting, current guidelines recommend eltrombopag as the drug of choice.Procedure The aim of this article is to summarize the available evidence and present real-life experience on eltrombopag as second-line therapy in pediatric patients with ITP, with a focus on dosing and response to therapy as well as its tapering and discontinuation.Results In our setting, eltrombopag is associated with good safety profile as well as promising efficacy; dose de-escalation was feasible in 94% of cases and often reached very low pro/kg dosage, with full discontinuation in 15% of cases. In daily practice, a standardized approach for discontinuation of eltrombopag in pediatric patients with ITP is still lacking. Herein, an easy-to-use scheme for tapering and discontinuation in candidate pediatric patients is proposed that proposes 25% dose reduction every four weeks.Conclusions In future management of pediatric ITP patients, it will be crucial to assess if thrombopoietin receptor agonists might be more effective in earlier phases of the disease and can modify the course of the disease

Retrospective evaluation of 90 children with essential thrombocythemia: the AIEOP experience

We report 90 children affected by ETevaluated over many years in the Units of Italian Association for Hemato-Oncolog