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398 results on '"Di Sabatino, Silvana"'

4. CFD characterization of street canyon heating by solar radiation on building walls

Author

Pulvirenti, Beatrice and Di Sabatino, Silvana

Subjects
Physics - Fluid Dynamics, Physics - Atmospheric and Oceanic Physics
Abstract

Heat exchange processes between building walls and external air within street canyons is an important topic in air quality modelling considering that the thermal fields largely affect local flow dynamics and pollutant concentration distribution. Despite the abundance of numerical studies, many questions still remain unanswered, ultimately limiting the inclusion of heat effects in mesocale atmospheric models. Of interest in this study is the assessment of radiative processes at building walls in terms of emissivity (i.e. is the ratio of the thermal radiation from a surface to the radiation from an ideal black surface at the same temperature), shape factors (i.e. the proportion of the radiation which leaves the surface of a building and strikes toward the surface of another building) and their relation to the Richardson number. The study is approached via the computational fluid dynamics code OpenFOAM, with large eddy simulations (LES) extension to model turbulence within the canyon and Boussinesq approach to model heat transfer. Consequences on pollutant concentrations are also analysed. A model for setting the thermal boundary conditions on the building surfaces is developed, based on a database that gives the correlations between the emissivity of a surface and the heat flux emitted by this surface, under certain weather conditions, as a function of the latitude and longitude of the surface, the orientation, the time of the day. As a novel result an exponential law between the transfer coefficient and Ri (as well as with the emissivity) is proposed as a function of the canyon aspect ratio., Comment: Conference paper presented at the HARMO18 conference in Bologna (http://www.harmo18.eu/)

Published
2020

5. The drag force distribution within regular arrays of cubes and its relation to cross ventilation: theoretical and experimental analyses

Author

Buccolieri, Riccardo, Sandberg, Mats, Wigö, Hans, and Di Sabatino, Silvana

Subjects
Physics - Fluid Dynamics
Abstract

A novel set of wind tunnel measurements of the drag force and its spatial distribution along aligned arrays of cubes of height H and planar area index lambdap (air gap between cubes) equal to 0.028 (5H) to 0.69 (0.2H) is presented and analysed. Two different types of measurements are compared: one type where the drag force is obtained using the standard load cell method, another type where the drag force is estimated by measuring the pressure difference between windward and the leeward facades. Results show that the drag force is nearly uniformly distributed for lower lambdap (0.028 and 0.0625), it decreases up to 50% at the second row for lambdap=0.11, and it sharply decreases for larger lambdap (from 0.25 to 0.69) where the force mostly acts on the first row. It follows that for the lowest lambdap the drag force typically formulated as a drag area corresponds to the total frontal area of the array, whereas for large lambdap the drag area corresponds to the area of the first row. By assessing the driving pressure for ventilation from the drag force, the analysis is extended to estimate the cross ventilation as an example of application of this type of measurements.

Published
2020
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6. Integrated Agent-based Microsimulation Framework for Examining Impacts of Mobility-oriented Policies

Author

Adnan, Muhammad, Outay, Fatma, Ahmed, Shiraz, Brattich, Erika, di Sabatino, Silvana, and Janssens, Davy

Subjects
Physics - Physics and Society, Statistics - Computation, 62P20
Abstract

Travel demand management measures/policies are important to sustain positive changes among individuals' travel behaviour. An integrated agent-based microsimulation platform provides a rich framework for examining such interventions to assess their impacts using indicators about demand as well as supply side. This paper presents an approach, where individual schedules, derived from a lighter version of an activity-based model, are fed into a MATSIM simulation framework. Simulations are performed for two European cities i.e. Hasselt (Belgium), Bologna (Italy). After calibrating the modelling framework against aggregate traffic counts for the base case, the impacts of a few traffic management policies (restricting car access, increase in bus frequency) are examined. The results indicate that restricting car access is more effective in terms of reducing traffic from the network and also shifting car drivers/passengers to other modes of travel. The enhancement of bus infrastructure in relation to increase in frequency caused shifting of bicyclist towards public transport, which is an undesirable result of the policy if the objective is to improve sustainability and environment. In future research, the framework will be enhanced to integrate emission and air dispersion models to ascertain effects on air quality as a result of such interventions., Comment: Post-print

Published
2020
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8. Quantifying the effects of nature-based solutions in reducing risks from hydrometeorological hazards: Examples from Europe

Author

Shah, Mohammad Aminur Rahman, Xu, Jiren, Carisi, Francesca, De Paola, Francesco, Di Sabatino, Silvana, Domeneghetti, Alessio, Gerundo, Carlo, Gonzalez-Ollauri, Alejandro, Nadim, Farrokh, Petruccelli, Natasha, Polderman, Annemarie, Pugliese, Francesco, Pulvirenti, Beatrice, Ruggieri, Paolo, Speranza, Giuseppe, Toth, Elena, Zieher, Thomas, and Renaud, Fabrice G.

Published
2023
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19. Characterizing hail-prone environments using convection-permitting reanalysis and overshooting top detections over south-central Europe.

Author

Giordani, Antonio, Kunz, Michael, Bedka, Kristopher M., Punge, Heinz Jürgen, Paccagnella, Tiziana, Pavan, Valentina, Cerenzia, Ines M. L., and Di Sabatino, Silvana

Subjects
SEVERE storms, METEOROLOGICAL satellites, SUMMER, REMOTE sensing, POTENTIAL energy, HAILSTORMS, HAIL
Abstract

The challenges associated with reliably observing and simulating hazardous hailstorms call for new approaches that combine information from different available sources, such as remote sensing instruments, observations, or numerical modelling, to improve understanding of where and when severe hail most often occurs. In this work, a proxy for hail frequency is developed by combining overshooting cloud top (OT) detections from the Meteosat Second Generation (MSG) weather satellite with convection-permitting High rEsolution ReAnalysis over Italy (SPHERA) reanalysis predictors describing hail-favourable environmental conditions. Atmospheric properties associated with ground-based reports from the European Severe Weather Database (ESWD) are considered to define specific criteria for data filtering. Five convection-related parameters from reanalysis data quantifying key ingredients for hailstorm occurrence enter the filter: most unstable convective available potential energy (CAPE), K index, surface lifted index, deep-layer shear, and freezing-level height. A hail frequency estimate over the extended summer season (April–October) in south-central Europe is presented for a test period of 5 years (2016–2020). OT-derived hail frequency peaks at around 15:00 UTC in June–July over the pre-Alpine regions and the northern Adriatic Sea. The hail proxy statistically matches with ∼63 % of confirmed ESWD reports, which is roughly 23 % more than the previous estimate over Europe coupling deterministic satellite detections with coarser global reanalysis ambient conditions. The separation of hail events according to their severity highlights the enhanced appropriateness of the method for large-hail-producing hailstorms (with hailstone diameters ≥ 3 cm). Further, signatures for missed small-hail occurrences are identified, which are characterized by lower instability and organization and warmer cloud top temperatures. [ABSTRACT FROM AUTHOR]

Published
2024
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21. Structure of Turbulence in Katabatic Flows below and above the Wind-Speed Maximum

Author

Grachev, Andrey A., Leo, Laura S., Di Sabatino, Silvana, Fernando, Harindra J. S., Pardyjak, Eric R., and Fairall, Christopher W.

Subjects
Physics - Atmospheric and Oceanic Physics
Abstract

Measurements of small-scale turbulence made over the complex-terrain atmospheric boundary layer during the MATERHORN Program are used to describe the structure of turbulence in katabatic flows. Turbulent and mean meteorological data were continuously measured at multiple levels at four towers deployed along the East lower slope (2-4 deg) of Granite Mountain. The multi-level observations made during a 30-day long MATERHORN-Fall field campaign in September-October 2012 allowed studying of temporal and spatial structure of katabatic flows in detail, and herein we report turbulence and their variations in katabatic winds. Observed vertical profiles show steep gradients near the surface, but in the layer above the slope jet the vertical variability is smaller. It is found that the vertical (normal to the slope) momentum flux and horizontal (along the slope) heat flux in a slope-following coordinate system change their sign below and above the wind maximum of a katabatic flow. The vertical momentum flux is directed downward (upward) whereas the horizontal heat flux is downslope (upslope) below (above) the wind maximum. Our study therefore suggests that the position of the jet-speed maximum can be obtained by linear interpolation between positive and negative values of the momentum flux (or the horizontal heat flux) to derive the height where flux becomes zero. It is shown that the standard deviations of all wind speed components (therefore the turbulent kinetic energy) and the dissipation rate of turbulent kinetic energy have a local minimum, whereas the standard deviation of air temperature has an absolute maximum at the height of wind-speed maximum. We report several cases where the vertical and horizontal heat fluxes are compensated. Turbulence above the wind-speed maximum is decoupled from the surface, and follows the classical local z-less predictions for stably stratified boundary layer., Comment: Manuscript submitted to Boundary-Layer Meteorology (05 December 2014)

Published
2015
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22. Characterization of the Morning Transition over the Gentle Slope of a Semi-Isolated Massif

Author

Farina, Sofia, Marchio, Mattia, Barbano, Francesco, Di Sabatino, Silvana, Zardi, Dino, Farina, Sofia, Marchio, Mattia, Barbano, Francesco, Di Sabatino, Silvana, and Zardi, Dino

Subjects
Turbulence, Atmospheric Science, Mountain meteorology, Energy budget/balance
Abstract

This paper investigates the surface-layer processes associated with the morning transition from nighttime downslope winds to daytime upslope winds over a semi-isolated massif. It provides an insight into the characteristics of the transition and its connection with the processes controlling the erosion of the temperature inversion at the foot of the slope. First, a criterion for the identification of days prone to the development of purely thermally driven slope winds is proposed and adopted to select five representative case studies. Then, the mechanisms leading to different patterns of erosion of the nocturnal temperature inversion at the foot of the slope are analyzed. Three main patterns of erosion are identified: the first is connected to the growth of the convective boundary layer at the surface, the second is connected to the descent of the inversion top, and the third is a combination of the previous two. The first pattern is linked to the initiation of the morning transition through surface heating, and the second pattern is connected to the top-down dilution mechanism and so to mixing with the above air. The discriminating factor in the determination of the erosion pattern is identified in the partitioning of turbulent sensible heat flux at the surface. Significance Statement The purpose of this study is to improve our understanding of the thermally driven slope circulations with a focus on the unsteady processes associated with the morning transition and the erosion patterns of the nocturnal temperature inversion, so far in the literature less investigated and understood than the evening transition. Understanding this diurnal process will advance our abilities to model it and to improve the accuracy of weather forecasting in complex terrain.

Published
2023

27. Performance evaluation of MeteoTracker mobile sensor for outdoor applications.

Author

Barbano, Francesco, Brattich, Erika, Cintolesi, Carlo, Ghafoor Nizamani, Abdul, Di Sabatino, Silvana, Milelli, Massimo, Peerlings, Esther E. M., Polder, Sjoerd, Steeneveld, Gert-Jan, and Parodi, Antonio

Subjects
DEW point, WEATHER, DETECTORS, METEOROLOGICAL stations, ATMOSPHERIC temperature, HUMIDITY
Abstract

The morphological complexity of urban environments results in a high spatial and temporal variability of the urban microclimate. The consequent demand for high-resolution atmospheric data remains a challenge for atmospheric research and operational application. The recent widespread availability and increasing adoption of low-cost mobile sensing offer the opportunity to integrate observations from conventional monitoring networks with microclimatic and air pollution data at a finer spatial and temporal scale. So far, the relatively low quality of the measurements and outdoor performance compared to conventional instrumentation has discouraged the full deployment of mobile sensors for routine monitoring. The present study addresses the performance of a commercial mobile sensor, the MeteoTracker (IoTopon Srl), recently launched on the market to quantify the microclimatic characteristics of the outdoor environment. The sensor follows the philosophy of the Internet of Things technology, being low cost, having an automatic data flow via personal smartphones and online data sharing, supporting user-friendly software, and having the potential to be deployed in large quantities. In this paper, the outdoor performance is evaluated through tests aimed at quantifying (i) the intra-sensor variability under similar atmospheric conditions and (ii) the outdoor accuracy compared to a reference weather station under sub-optimal (in a fixed location) and optimal (mobile) sensor usage. Data-driven corrections are developed and successfully applied to improve the MeteoTracker data quality. In particular, a recursive method for the simultaneous improvement of relative humidity, dew point, and humidex index proves to be crucial for increasing the data quality. The results mark an intra-sensor variability of approximately ± 0.5 °C for air temperature and ± 1.2 % for the corrected relative humidity, both of which are within the declared sensor accuracy. The sensor captures the same atmospheric variability as the reference sensor during both fixed and mobile tests, showing positive biases (overestimation) for both variables. Through the mobile test, the outdoor accuracy is observed to be between ± 0.3 to ± 0.5 °C for air temperature and between ± 3 % and ± 5 % for the relative humidity, ranking the MeteoTracker in the real accuracy range of similar commercial sensors from the literature and making it a valid solution for atmospheric monitoring. [ABSTRACT FROM AUTHOR]

Published
2024
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28. Introducing the Bulletin of Atmospheric Science and Technology

Author

Di Girolamo, Paolo, Di Sabatino, Silvana, Archer, Cristina Lozej, Buontempo, Carlo, Bordoni, Simona, Budillon, Giorgio, Buzzi, Andrea, Cimini, Domenico, Curci, Gabriele, Cuxart, Joan, Davolio, Silvio, Ferretti, Rossella, Gerosa, Giacomo, Marzano, Frank, Miglietta, Mario Marcello, Paccagnella, Tiziana, Petitta, Marcello, Pilla, Francesco, Richard, Evelyne, Rotunno, Richard, Serafin, Stefano, Serio, Carmine, Troccoli, Alberto, and Zardi, Dino

Published
2020
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29. Preface

Author

Di Sabatino, Silvana and Princevac, Marko

Subjects
Mathematical Sciences, Physical Sciences, Engineering, Meteorology & Atmospheric Sciences
Published
2015

36. DEVELOPING A RESEARCH STRATEGY TO BETTER UNDERSTAND, OBSERVE, AND SIMULATE URBAN ATMOSPHERIC PROCESSES AT KILOMETER TO SUBKILOMETER SCALES

Author

Barlow, Janet, Best, Martin, Bohnenstengel, Sylvia I., Clark, Peter, Grimmond, Sue, Lean, Humphrey, Christen, Andreas, Emeis, Stefan, Haeffelin, Martial, Harman, Ian N., Lemonsu, Aude, Martilli, Alberto, Pardyjak, Eric, Rotach, Mathias W, Ballard, Susan, Boutle, Ian, Brown, Andy, Cai, Xiaoming, Carpentieri, Matteo, Coceal, Omduth, Crawford, Ben, Di Sabatino, Silvana, Dou, Junxia, Drew, Daniel R., Edwards, John M., Fallmann, Joachim, Fortuniak, Krzysztof, Gornall, Jemma, Gronemeier, Tobias, Halios, Christos H., Hertwig, Denise, Hirano, Kohin, Holtslag, Albert A. M., Luo, Zhiwen, Mills, Gerald, Nakayoshi, Makoto, Pain, Kathy, Schlünzen, K. Heinke, Smith, Stefan, Soulhac, Lionel, Steeneveld, Gert-Jan, Sun, Ting, Theeuwes, Natalie E, Thomson, David, Voogt, James A., Ward, Helen C., Xie, Zheng-Tong, and Zhong, Jian

Published
2017

41. Introducing the Bulletin of Atmospheric Science and Technology

Author

Di Girolamo, Paolo, Di Sabatino, Silvana, Archer, Cristina Lozej, Buontempo, Carlo, Bordoni, Simona, Budillon, Giorgio, Buzzi, Andrea, Cimini, Domenico, Curci, Gabriele, Cuxart, Joan, Davolio, Silvio, Ferretti, Rossella, Gerosa, Giacomo, Marzano, Frank, Miglietta, Mario Marcello, Paccagnella, Tiziana, Petitta, Marcello, Pilla, Francesco, Richard, Evelyne, Rotunno, Richard, Serafin, Stefano, Serio, Carmine, Troccoli, Alberto, and Zardi, Dino

Published
2024
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45. Characterizing hail-prone environments using convection-permitting reanalysis and overshooting top detections over south-central Europe.

Author

Giordani, Antonio, Kunz, Michael, Bedka, Kristopher M., Punge, Heinz Jurgen, Paccagnella, Tiziana, Pavan, Valentina, Cerenzia, Ines M. L., and Di Sabatino, Silvana

Subjects
HAILSTORMS, HAIL, SEVERE storms, METEOROLOGICAL satellites, SUMMER, REMOTE sensing, POTENTIAL energy
Abstract

The challenges associated with reliably observing and simulating hazardous hailstorms call for new approaches that combine information from different available sources, such as remote sensing instruments, observations, or numerical modeling, to improve understanding of where and when severe hail most often occurs. In this work, a proxy for hail frequency is developed by combining overshooting cloud top (OT) detections from the Meteosat Second Generation (MSG) weather satellite with convection-permitting SPHERA reanalysis predictors describing hail-favorable environmental conditions. Atmospheric properties associated with ground-based reports from the European Severe Weather Database (ESWD) are considered to define specific criteria for data filtering. Five convection-related parameters from reanalysis data quantifying key ingredients for hailstorm occurrence enter the filter, namely: most unstable convective available potential energy (CAPE), K index, surface lifted index, deep-layer shear, and freezing level height. A hail frequency estimate over the extended summer season (April-October) in south-central Europe is presented for a test period of 5 years (2016-2020). OT-derived hail frequency peaks at around 15 UTC in June-July over the pre-Alpine regions and the northern Adriatic sea. The hail proxy statistically matches with ~ 62% of confirmed ESWD reports, which is roughly 22% more than the previous estimate over Europe coupling deterministic satellite detections with coarser global reanalysis ambient conditions. The separation of hail events according to their severity highlights enhanced appropriateness of the method for large-hail-producing hailstorms (with hailstones diameters > 3 cm). Further, signatures for small-hail missed occurrences are identified, which are characterized by lower instability and organization, and warmer cloud-top temperatures. [ABSTRACT FROM AUTHOR]

Published
2023
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