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Francesca DESPINI

Personale tecnico amministrativo
Dipartimento di Ingegneria "Enzo Ferrari"

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2022 - Identification of SUHI in Urban Areas by Remote Sensing Data and Mitigation Hypothesis through Solar Reflective Materials [Articolo su rivista]
Costanzini, S.; Despini, F.; Beltrami, L.; Fabbi, S.; Muscio, A.; Teggi, S.

The urban heat island (UHI) is an increasingly widespread phenomenon of concern to the wellbeing and the health of populations living in urban environments. The SUHI (Surface UHI) is directly related to UHI and influences its extension and intensity. Satellite images in the thermal infrared spectral region can be used to identify and study the SUHI. In this work, Landsat 8 TIR images were acquired to study the SUHI of a medium-sized municipality of the Po valley in the northern part of Italy. An additional Worldview 3 satellite image was used to classify the study area and retrieve the surface albedo of building roofs. Using the Local Climate Zone approach, existing roof materials were virtually replaced by solar reflective materials, and the mitigation potential of the SUHI and the UHI was quantified. This virtual scenario shows a decrease in the overheating of building roofs with respect to the ambient temperature of up to 33% compared to the current situation in the industrial areas. Focusing on UHI intensity, the air temperature decrease could be up to 0.5◦C.

2022 - The new Unimore interdisciplinary teaching on transversal sustainability skills [Articolo su rivista]
Ghermandi, Grazia; Despini, Francesca

The global situation of the Covid-19 pandemic has changed several aspects of University life and management. In this context, the University of Modena and Reggio Emilia (Unimore) has introduced a new course for all of its students called "Transversal Skills on Sustainability". This course consists of 13 Modules offered by the various Unimore Departments to address the issue of Sustainability at 360 degrees. Each Department offers a thematic module concerning Sustainability in its own field of study and research. The course ranges from engineering issues with renewable energy, waste, air quality, to economics and sustainable finance. In addition, the course deals with issues related to sustainability in the medical, chemical and legal fields and many others. In this first year of delivery, this teaching has proven to be highly appreciated among students. Over 950 students have enrolled in teaching for the 2020/2021 academic year. Enrolled students come from all areas of the university: there are students of engineering, geology, economics, chemistry, but also of medicine, pharmacy, and many others.

2021 - Standard test methods for rating of solar reflectance of built-up surfaces and potential use of satellite remote sensors [Articolo su rivista]
Costanzini, S.; Ferrari, C.; Despini, F.; Muscio, A.

More and more attention is being paid to the solar reflectance of built-up surfaces due to its influence on the summer heating of buildings and urban areas and the consequent effects on energy needs for air conditioning, as well as on the peak load of the electric grid. Several standard test methods are available for measuring solar reflectance in the laboratory or in the field, based on different devices and approaches. A convergence of some methods has been achieved by rating programs in the U.S. and, more recently, in Europe and other areas. However, laboratory or field measurements are impractical for characterizing a large number of urban surfaces—whether it is for identifying critical issues, developing policies, or verifying compliance with building requirements. In this regard, satellite remote sensors have recently become available, through which it is possible to estimate the reflectance of roof and pavement surfaces thanks to a spatial resolution that is suitable for identifying and characterizing individual built-up surfaces. In the present paper, the most-used standard test methods for rating of solar reflectance are reviewed. Subsequently, some publicly accessible satellite sensors are examined, through which comparable measurements could be obtained.

2021 - Urban surfaces analysis with remote sensing data for the evaluation of UHI mitigation scenarios [Articolo su rivista]
Despini, F.; Ferrari, C.; Santunione, G.; Tommasone, S.; Muscio, A.; Teggi, S.

Considering the new IPCC report and its recent suggestions, it is important to pay serious attention to the Urban Heat Island issue. In this study, satellite images acquired by the Worldview3 sensor (WV3) were processed to classify the different kinds of urban surface and to compute the albedo value for each surface. Then several UHI mitigation scenarios were analyzed, varying selectively the surface albedo by choosing solar reflective materials. Clay tile pitched roofs, dark roofs and parking areas were considered as “modifiable surfaces” and their albedo values were increased on the basis of the literature and of data made available by product manufacturers. For each proposed scenario, the reduction of intensity of the Urban Heat Island effect (ATD), the energy saving brought by lower absorption of air conditioning systems (ΔE) and the consequent cost savings were calculated. All the scenarios proved to be convenient and with a relatively fast return on investment. In particular, two scenarios involving the modification of several surfaces at the same time proved to be the most promising ones from the perspective of a public administration, with significant benefits on the well-being of the population, as well as with similar and relatively short payback periods.

Ghermandi, Grazia; Despini, Francesca

La formazione transdisciplinare sulla sostenibilità è riconosciuta come indispensabile in ogni ambito, professionale, politico, sociale. La situazione globale pandemica di Covid-19 ha modificato diversi aspetti della vita e della gestione degli Atenei, italiani e mondiali, fra cui certamente le modalità di erogazione della didattica. In questo contesto, l'Università degli Studi di Modena e Reggio Emilia (Unimore) ha introdotto un nuovo insegnamento aperto a tutti gli studenti, denominato "Competenze Trasversali sulla Sostenibilità", fruibile on line. L’insegnamento si compone di 12 moduli offerti dai diversi Dipartimenti di Unimore, che affrontano il tema della Sostenibilità da ogni prospettiva. Ciascun Dipartimento propone uno o più moduli tematici relativi alla Sostenibilità nei propri ambiti di studio e ricerca. L’insegnamento quindi spazia da moduli su energie rinnovabili, gestione rifiuti, qualità dell'aria, cambiamenti climatici, rischi naturali e antropici, fino ad altri su economia e finanza sostenibile e alla sostenibilità in ambito medico e legale, nella filosofia e nelle scienze umane. Nel primo anno di erogazione, 2020/2021, questo insegnamento ha riscosso grande interesse fra gli studenti. Oltre 950 studenti si sono iscritti, provenienti da tutti i corsi di studio dell'Ateneo, sia di primo che di secondo livello (triennali e magistrali) che a ciclo unico.

2020 - Urban tree species identification and carbon stock mapping for urban green planning and management [Articolo su rivista]
Choudhury, M. A. M.; Marcheggiani, E.; Despini, F.; Costanzini, S.; Rossi, P.; Galli, A.; Teggi, S.

Recently, the severe intensification of atmospheric carbon has highlighted the importance of urban tree contributions in atmospheric carbon mitigations in city areas considering sustainable urban green planning and management systems. Explicit and timely information on urban trees and their roles in the atmospheric Carbon Stock (CS) are essential for policymakers to take immediate actions to ameliorate the effects of deforestation and their worsening outcomes. In this study, a detailed methodology for urban tree CS calibration and mapping was developed for the small urban area of Sassuolo in Italy. For dominant tree species classification, a remote sensing approach was applied, utilizing a high-resolution WV3 image. Five dominant species were identified and classified by applying the Object-Based Image Analysis (OBIA) approach with an overall accuracy of 78%. The CS calibration was done by utilizing an allometric model based on the field data of tree dendrometry—i.e., Height (H) and Diameter at Breast Height (DBH). For geometric measurements, a terrestrial photogrammetric approach known as Structure-from-Motion (SfM) was utilized. Out of 22 randomly selected sample plots of 100 square meters (10 m × 10 m) each, seven plots were utilized to validate the results of the CS calibration and mapping. In this study, CS mapping was done in an efficient and convenient way, highlighting higher CS and lower CS zones while recognizing the dominant tree species contributions. This study will help city planners initiate CS mapping and predict the possible CS for larger urban regions to ensure a sustainable urban green management system.

2019 - Impact assessment of vehicular exhaust emissions by microscale simulation using automatic traffic flow measurements [Articolo su rivista]
Ghermandi, Grazia; Fabbi, Sara; Bigi, Alessandro; Veratti, Giorgio; Despini, Francesca; Teggi, Sergio; Barbieri, Carla; Torreggiani, Luca

In order to assess the impact of traffic on local air quality a microscale simulation of pollutant concentration fields was produced for two busy intersections, in Reggio Emilia and in Modena, Italy. The simulation was performed by the model suite Micro-Swift-Spray, a Lagrangian particle dispersion model accounting for buildings. Direct measurements of traffic flow were continuously collected in Reggio Emilia over the period January 13–24, 2014 by a two channel radar traffic counter and in Modena from October 28 to November 8, 2016 by four single channel radar traffic counters and used for the hourly modulation of vehicular emissions. Combining radar counts with vehicular fleet composition for each municipality, specific emission factors were obtained. For both cities, simulated concentration fields were compared to local air quality measurements at the nearest urban traffic and urban background sites. The simulated NOx showed large correlation with the observations, notwithstanding some underestimation. The results proved the reliability of the procedure and provided a fair estimate of the NO2 mass fraction of total NOx (primary NO2) due to vehicular emissions in the investigated traffic sites.

2019 - Photogrammetry and Remote Sensing for the identification and characterization of trees in urban areas [Articolo su rivista]
Mueed Choudhury, M. A.; Costanzini, S.; Despini, F.; Rossi, P.; Galli, A.; Marcheggiani, E.; Teggi, S.

For the last few decades, there have been a lot of studies recognising the significant roles of the urban trees as a high-quality carbon sink. This work is a preliminary study about how remote sensing and photogrammetry could be useful tools to identify urban trees for the purpose of Carbon Storage (CS) computation in urban areas. Our first study area is a typical urban park located in Sassuolo, a municipality in the northern part of Italy in the so-called "Pianura Padana". We measured the tree Height (H) and the Diameter at Breast Height (DBH), required for the calibration of the CS, based on the tree allometry during the field data collection along with the constructing a 3D model through the photogrammetric approach. A high-resolution WorldView (WV) 3 satellite image of the same area, was classified using an object-oriented approach to count the number of trees varied with different species. This preliminary study will enhance the possibilities of the application of these approaches in case of the larger urban areas to ascertain the accuracy of the tree CS calibration.

2018 - A multi-temporal analyses of Land Surface Temperature using Landsat-8 data and open source software: The case study of Modena, Italy [Articolo su rivista]
Barbieri, Tommaso; Despini, Francesca; Teggi, Sergio

The Urban Heat Island (UHI) phenomenon, namely urban areas where the atmospheric temperature is significantly higher than in the surrounding rural areas, is currently a very well-known topic both in the scientific community and in public debates. Growing urbanization is one of the anthropic causes of UHI. The UHI phenomenon has a negative impact on the life quality of the local population (thermal discomfort, summer thermal shock, etc.), thus investigations and analyses on this topic are really useful and important for correct and sustainable urban planning; this study is included in this context. A multi-temporal analysis was performed in the municipality of Modena (Italy) to identify and estimate the Surface Urban Heat Island (SUHI, strictly correlated to the UHI phenomenon) from 2014 to 2017. For this purpose, Landsat-8 satellite images were processed with Quantum Geographic Information System (QGIS) to obtain the Land Surface Temperature (LST) and the Normalized Difference Vegetation Index (NDVI). For every pixel, LST and NDVI values of three regions of interest (ROI, i.e., Countryside, Suburbs, and City Center) were extracted and their correlations were investigated. A maximum variation of 6.4 °C in the LST values between City Center and Countryside was highlighted, confirming the presence of the SUHI phenomenon even in a medium-sized municipality like Modena. The implemented procedure demonstrates that satellite data are suitable for SUHI identification and estimation, therefore it could be a useful tool for public administration for urban planning policies.

2016 - Correlation between remote sensing data and ground based measurements for solar reflectance retrieving [Articolo su rivista]
Despini, Francesca; Ferrari, Chiara; Bigi, Alessandro; Libbra, Antonio; Teggi, Sergio; Muscio, Alberto; Ghermandi, Grazia

Surface and atmospheric modifications due to urbanization generally lead to the urban heat island effect (UHI). This phenomenon is an issue of growing interest and has long been studied by ground based observation. With the advent of remote sensing technologies, observation of UHIs became possible with airborne and spaceborne sensors. Remote sensing data allow urban surfaces characterization to study UHI mitigation methodologies such as the application of cool roofs and cool colors. In this study remote sensing data have been used first to identify urban surfaces and then to retrieve the solar reflectance value of these surfaces. The first area of interest is the city of Modena in the Emilia Romagna region (Italy). On this area orthorectified images by an airborne sensor are used. Available images do not allow to directly obtain the solar reflectance value. Therefore it has been investigated a correlation between satellite remote sensing data and ground based measurements. The solar reflectance was obtained for all urban surfaces of interest such as roofs and pavements. In this way it was possible to assess the real situation and to hypothesize achievable improvements in the solar reflectance of several urban surfaces aimed at improving thermal comfort and energy efficiency of buildings.

2014 - Estimation of subpixel MODIS water temperature near coastlines using the SWTI algorithm [Articolo su rivista]
Teggi, Sergio; Despini, Francesca

Satellite derived water surface temperature maps are widely used in many environmental studies and applications. The Moderate Resolution Imaging Spectroradiometer (MODIS) is among the widely used sensors in this field and sea surface temperature (SST) is one of the standard quantities derived from MODIS imagery. However, MODIS SST maps have limited applications in near-shore and coastal environments due to inadequate spatial resolution of 1km. This problem means that the MODIS pixels closer than 1km from the shore are mixed pixels, i.e. they include by both water and land, and must be discarded from the SST map. In this work SWTI (Sharpening Water Thermal Imagery) methods were applied to MODIS thermal imagery for the first time. The information required by SWTI regarding cover fractions and perpendicular vegetation index was obtained from the MODIS images in the Visible-Near Infrared bands at a spatial resolution of 250m. In this way, the SST MODIS maps were extended to a minimum distance of 250m from the shore. The SWTI results were evaluated using as a reference the SST computed from two ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) images acquired simultaneously to the MODIS images and covering the same areas. The applied validation methodology provides an evaluation of the deviations introduced by SWTI separated from the pre-existing differences between MODIS SST and ASTER SST upscaled to 250m. For sea coast environments, SWTI was able to compute the SST of more than 80% of the pixels close to the shore at a spatial resolution of 250m. This represents an increase of 67% compared to the number of pixels obtainable using a simple downscaling method based on polynomial interpolation; in areas with lagoons and estuaries the increases were +70% and +60% respectively. The ASTER SST comparison showed that the SST bias and the unsystematic deviation introduced by SWTI were S≤0.45K and σ(εS)≤0.88K respectively, corresponding to a total deviation TD≤0.97K. SWTI is written in the IDL language and could be adapted for automatic application to MODIS images.

2014 - Methods and metrics for the assessment of Pan-sharpening algorithms [Relazione in Atti di Convegno]
Despini, Francesca; Teggi, Sergio; Baraldi, Andrea

Recent remote sensing applications require sensors that provide both high spatial and spectral resolution, but this is often not possible for economic and constructive reasons. The "fusion" of images at different spatial and spectral resolution is a method widely used to solve this problem. Pan-sharpening techniques have been applied in this work to simulate PRISMA images. The work presented here is indeed part of the Italian Space Agency project “ASI-AGI”, which includes the study of a new platform, PRISMA, consisting of an hyperspectral sensor with a spatial resolution of 30 m and a panchromatic sensor with a spatial resolution of 5 m, for monitoring and understanding the Earth's surface. Firstly, PRISMA images have been simulated using images from MIVIS and Quickbird sensors. Then several existing fusion methods have been tested in order to identify the most suitable for the platform PRISMA in terms of spatial and spectral information preservation. Both standard and wavelet algorithms have been used: among the former there are Principal Component Analysis and Gram-Schmidt transform, and among the latter are Discrete Wavelet Transform and the “à trous” wavelet transform. Also the Color Normalized Spectral Sharpening method has been used. Numerous quality metrics have been used to evaluate spatial and spectral distortions introduced by pan-sharpening algorithms. Various strategies can be adopted to provide a final rank of alternative algorithms assessed by means of a battery of quality indexes. All implemented statistics have been standardized and then three different methodologies have been used to achieve a final score and thus a classification of pan-sharpening algorithms. Currently a new protocol is under development to evaluate the preservation of spatial and spectral information in fusion methods. This new protocol should overcome the limitations of existing alternative approaches and be robust to changes in the input dataset and user-defined parameters.

2014 - Preliminary analysis of urban surfaces for the characterizaͳ tion and the mitigation of the heat island effect [Relazione in Atti di Convegno]
Despini, Francesca; Teggi, Sergio; Muscio, Alberto; Ghermandi, Grazia

The urban heat island (UHI) phenomenon is an issue of growing interest and the subject of numerous studies. UHI is defined as the metropolitan area that is significantly warmer than its surrounding rural areas. UHI has significant impacts on the buildings energy consumption and outdoor air quality, therefore it is considered an important environmental topic. The most effective approaches to mitigate UHI include, among others, the albedo increase of materials used for manmade surfaces (e.g. pavements, roofs), the increment of vegetated areas (e.g. parks, flowerbed, gardens), the increment of water surfaces (e.g. ponds). The UHI mitigation results in a reduction of the energy consumption and in an improvement of outdoor air quality. A recent model study carried by Rossi et al. (CIRIAF, University of Perugia) correlated the increase of materials albedo with energy saving in terms of reduction of carbon dioxide emissions. Therefore surfaces characterization is an useful information for planning UHI mitigation actions. Albedo of different types of urban surfaces can be obtained from bibliographic data, from laboratory measurements or retrieved from spaceborne or airborne remote sensing data. This data reported surface reflectance for each band, from which albedo can be directly obtained. In this work, airborne remote sensing data have been used for UHI characterization and for the study of UHI mitigation. The area of interest is the city of Modena in the Emilia Romagna region (Italy). On this area four orthorectified images acquired in the electromagnetic regions of the visible and near-infrared by an airborne sensor with a spatial resolution of 2 meters are used. Using an object-oriented technique, the four images have been segmented and classified into categories representing different types of land cover significant for UHI: Cultivated Soils, Green Areas, Roads, Parking, Railways and Buildings. The "Buildings" class is further divided in pitched roofs made of tiles (typical buildings of the historical center of the city) and in flat roofs of industrial buildings with both bright and dark coverings. This information will be used in the model described above in order to study UHI mitigation. This study presents some preliminary results of the application of this methodology that will be developed in the upcoming years for the application to various sites of interest.

2013 - Analysis of temperature maps of waterbodies obtained from ASTER TIR images [Articolo su rivista]
Despini, Francesca; Teggi, Sergio

Thermal water pollution is a highly relevant issue to which increasing attention is being paid. Satellite remote sensing represents a useful tool for the mointoring and study of the temperatures of waterbodies. The purpose of this work is to define a methodology for the analysis of the surface temperature maps of coastal waterbodies and watercourses from satellite images for quality assessment and for regulatory purposes. Three different procedures are developed in order to study the temperature field of waterbodies, to extract the temperature profile at a fixed distance from the coastline and to analyse the cross sections of the watercourses as prescribed by the law. Extraction and analysis of surface temperature patterns are undertaken using image segmentation techniques. This work also represents a first test of the advantages given by the Sharpening Water Thermal Imagery (SWTI) algorithm, which improves the spatial resolution of Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) images from 90 to 30 m. The developed procedures and the SWTI algorithm are applied to ASTER images acquired on the lagoon of Venice and on the delta of the Po River. Statistical parameters and temperature profile are extracted in order to verify compliance with legal limits. The use of the developed procedures enables the individuation and quantification of thermal anomalies such as industrial discharges both in the sea and in watercourses. © 2013 Copyright Taylor and Francis Group, LLC.

2013 - Attempt of identification of wet areas with ASTER images for archeological studies [Relazione in Atti di Convegno]
Bertacchini, Eleonora; Despini, Francesca; Teggi, Sergio; Capra, Alessandro; M., Dubbini

Satellite images are a tool increasingly used in environmental monitoring and in recent years have become also strongly used in the field of archaeology. In this study it was conducted an experimental analysis on the identification of wetlands from satellite images in order to identify sites of interest from the archaeological point of view because probable sites of ancient settlements. The studied area is the Plan de la Limagne which is located in North-East of the French city of Clermont-Ferrand. For wet areas identification were used two ASTER satellite images and pre-existing carthography. Different indexes have been used to identify wet areas. First of all, it was used the NDVI (Normalized Difference Vegetation Index) to discriminate bare soils. Secondly, through the Tasseled Cap transform, other indexes were obtained, such as the Greeness Index, the Brightness Index (SBI - Soil Brightnes Index) and the Wetness Index. Then it has been used the ATI index (Apparent Thermal Inertia) that provides information on the thermal inertia of soils. Through these indexes, visual inspection and the study of spectral signatures, it has been tried not only to identify wetlands within the images, but also to find repeatable processes for the detection of these areas. Some "anomalous" areas, that are probably wet areas, have been identified with this procedure. The identification of wet areas has been carried out in a raw way, this is surely a first approximation analysis. Certainly the in situ analysis would provide the possibility of a better evaluation, in fact field measurements could be used to calibrate the model and then find an effective and repeatable procedure for identifying wetlands.

2012 - SPOT5 imagery for soil salinity assessment in Iraq [Relazione in Atti di Convegno]
Teggi, Sergio; Costanzini, Sofia; Despini, Francesca; P., Chiodi; F., Immordino

Soil salinization is a form of topsoil degradation due to the formation of soluble salts at deleterious levels. This phenomenon can seriously compromise vegetation health and agricultural productivity, and represents a worldwide environmental problem. Remote sensing is a very useful tool for soil salinization monitoring and assessment. In this work we show some results of a study aimed to define a methodology for soil salinity assessment in Iraq based on SPOT 5 imagery. This methodology allows the identification of salinized soils primarily on bare soils. Subsequently some soil salinity assessment can be done on vegetated soils. On bare soil the identification of salt is based on spectral analysis, using the Minimum Noise Fraction transformation and several indexes found in literature. In case of densely vegetated soils the methodology for the discrimination of salinized soils has been integrated with the results obtained from the classification of vegetation coverage. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

2012 - Soil salinization assessment on Iraq using satellite remote sensing imagery [Relazione in Atti di Convegno]
Teggi, Sergio; S., Costanzini; Despini, Francesca; Ghermandi, Grazia; F., Immordino

Soil salinization is a form of topsoil degradation due to the formation of soluble salts at deleterious levels. This phenomenon can seriously compromise vegetation health and agricultural productivity, and represents a worldwide environmental problem. Remote sensing is a very useful tool for soil salinization monitoring and assessment. In this work we show some results of a study aimed to define the most suitable remote sensing methodologies for soil salinity assessment in Iraq. This activity is part of the Strategies for Water and Land Resources in Iraq project. The satellite images used were acquired by the ETM+ and by the SPOT5 satellite sensors, in the Visible-Near Infrared electromagnetic region, and with spatial resolution of 30 m (ETM+) and of 10 m (SPOT5). The methods used for the investigation of bare soils and vegetation can be summarized in: pre-elaborations (atmospheric corrections, georeferentiation, reflectance computation); individuation of bare soils and of vegetated soils; analysis of the correlations between several surface quantities computed from the satellite images and soil salinity indicators; analysis of the suitability of these quantities for soil salinity classification of the images using for example class separability analysis, principal component analysis and vegetation indexes. The first results obtained indicate that some areas with soil salinization, in particular those with outcrop of salt at the surface, and different type of vegetation can be individuated. The work carried out until now shows that remote sensing images could be fruitfully used for the soil salinization characterization of the studied area, but the definition of the methodology would require a dataset of ground information that describes in detail the actual soil salinization.

2011 - Improvement of the spatial resolution of MODIS coastal waters thermal mapping [Relazione in Atti di Convegno]
Teggi, Sergio; Despini, Francesca; Ghermandi, Grazia; M., Serafini

Thermal mapping is an highly relevant tool for the assessment of the quality of coastal waters. Remote sensing is an useful technique for monitoring large surfaces in near real time, nevertheless, spatial resolution represents an important limiting factor. In this work it the spatial improvement, from 1km to 250m, of MODIS thermal imagery on coastal water obtained with the SWTI (SharpeningWater Thermal Imagery) is shown. This algorithm is applied, for the first time, to MODIS images acquired on the lagoon of Venice and on the delta of the Po River. The performances of SWTI are evaluated taking as a reference a couple of ASTER images acquired simultaneously to the MODIS images and on the same areas. Moreover, the water temperatures obtained with a simple bilinear interpolation of the MODIS images is also considered. Several statistical parameters, as bias and root mean square difference, are used to quantify the the difference between ASTER and MODIS/SWTI water temperatures along coastlines. In all the the cases these differences are lower than 1K.

2011 - Miglioramento della risoluzione spaziale di immagini TIR MODIS su aree costiere [Relazione in Atti di Convegno]
Teggi, Sergio; Despini, Francesca; M., Serafini

Thermal mapping of water bodies is an highly relevant tool for the study of thermal pollution, an issue to which increasing attention is paid. Remote sensing is an useful tool for monitoring large surface in near real time, but the main limiting factor is the spatial resolution. In this work it is shown the spatial improvement of MODIS thermal imagery on coastal water obtained with the SWTI (Sharpening Water Thermal Imagery) algorithm that allows to increase spatial resolution from 1 km to 250 m. SWTI is applied to two MODIS images, acquired on the lagoon of Venice and the delta of the Po river. As a reference we use a couple of ASTER images acquired simultaneously to the MODIS images and on the same areas. The root mean square errors computed excluding outliers are lower than 1.5 K that can be considered satisfactory when compared with the ASTER and MODIS temperature accuracies.

2010 - Analisi di mappature termiche di acque costiere e corsi d’acqua ottenute da immagini ASTER [Relazione in Atti di Convegno]
Despini, Francesca; Teggi, Sergio

The ASTER sensor is, currently, the main radiometer that acquires information in the Thermal Infrared (TIR) region with a spatial resolution of 90 m. The purpose of this work is to develop a working methodology for the analysis of water temperature obtained from ASTER images. Images were initially processed with an algorithm that improves spatial resolution from 90 m to 30 m using information drawn from the Visibile-Near infrared (VNIR) ASTER bands. Then data were analyzed and classified with an object-oriented approach. Specific procedures were developed in order to automate the monitoring process and to better interpret and display water temperature of the analyzed images. The studies were performed both on images at 90 m and at 30 m (computed with the algorithm for improving the spatial resolution). In this way it was possible to test the effectiveness and validity of the algorithm. For example, watercourses in the image at 90 m were barely visible while in the image at 30 m can be easily analyzed. This study is not concluded: the procedures will be soon applied to a wider range of case studies. Thus it will be possible to verify the versatility of the procedures themselves, and the advantages from the use of the algorithm for improving the spatial resolution.

2009 - Applications of Terra MODIS data for Iraq marshland monitoring [Relazione in Atti di Convegno]
Despini, Francesca; Teggi, Sergio; L., Bovio; F., Immordino

Since the 1970s, the Iraq Marshlands have been damaged significantly, but recently (May 2003-March 2004), more than 20% of the original marshland area has been re-flooded.The goal of the work is to observe the evolution of the marshes in terms of extension and to evaluate the success of wetland restoration on the base of multispectral and multitemporal MODIS images collected in 2007-2008.MODIS (MODerate resolution Imaging Spectroradiometer) has a viewing swath width of 2,330 km and views the entire surface of the Earth every one to two days. Its detectors measure 36 spectral bands between 0.405 and 14.385 μm, and it acquires data at three spatial resolutions -- 250m, 500m, and 1,000m.These data with their low spatial resolution but high time frequency are suitable for regional-scale time-series studies.The satellite data have been corrected for atmospheric effects using an IDL (Interactive Data Language) procedure based on MODTRAN and 6S radiative transfer codes. These radiative transfer codes require, in input, atmospheric vertical profiles, aerosol optical thickness(AOT) and columnar water vapour content (WV). Vertical profiles are obtained from the nearest meteorological station or by climatological data set. AOT and WV are retrieved either from the MODIS MODATML2 atmospheric product, or from the AERONET (Aerosol robotic network).Then different classifications (Pixel- and Object-Oriented) have been tested, compared and discussed to evaluate the best approach to apply on regional-scale time-series studies