1,721,129 research outputs found
Development of monitoring and GIS systems to assess distribution and diffusion of D. suzukii
Full text linkEnvironmental modelling and spatial ecology with focus on invasive Aedes mosquitoes and emergent mosquito-borne pathogens
Full text linkBiological invasions are a side effect of globalisation and human modification of natural systems. Invasive mosquitoes and the pathogens that they carry are leading causes of human suffering. Mosquito vectors of pathogens are often ecologically plastic and able to exploit human movements to disperse. As such they spread across wide geographical areas and are among the most successful species to have become invasive. Mosquito-borne pathogens have complex life cycles which involve a rich set of reservoir and vector hosts. They are evolutionarily very dynamic, ready to take advantage of new opportunities offered by anthropogenic environmental changes. Many pathogens associated with mosquitoes are indeed changing their ecology or modifying their geographical and biological distribution, being considered as invasive species. Despite this impressive plasticity, invasive mosquitoes and mosquito-borne pathogens are still part of a natural system, and as such are limited by environmental conditions. The main target of my research was to apply ecological theory and environmental modelling to gain knowledge on these limiting conditions, by establishing mechanistic and correlative associations between the environment, invasive vectors and pathogen demographics, as well as physiological and spatial dynamics. Understanding these mechanisms is key to design effective health policies which aim to mitigate the emergence of new pathogens, mainly by hindering the population that vectors them. The core of this thesis is formed by a series of stand-alone scientific papers, published, submitted or close to submission to peer-reviewed journals; the core chapters are backed by the General Introduction, and the General Summary and Outlook
Terra and Aqua satellites track tiger mosquito invasion: modelling the potential distribution of <it>Aedes albopictus </it>in north-eastern Italy
Full text linkAbstract Background The continuing spread of the Asian tiger mosquito Aedes albopictus in Europe is of increasing public health concern due to the potential risk of new outbreaks of exotic vector-borne diseases that this species can transmit as competent vector. We predicted the most favorable areas for a short term invasion of Ae. albopictus in north-eastern Italy using reconstructed daily satellite data time series (MODIS Land Surface Temperature maps, LST). We reconstructed more than 11,000 daily MODIS LST maps for the period 2001-09 (i.e. performed spatial and temporal gap-filling) in an Open Source GIS framework. We aggregated these LST maps over time and identified the potential distribution areas of Ae. albopictus by adapting published temperature threshold values using three variables as predictors (0°C for mean January temperatures, 11°C for annual mean temperatures and 1350 growing degree days filtered for areas with autumnal mean temperatures > 11°C). The resulting maps were integrated into the final potential distribution map and this was compared with the known current distribution of Ae. albopictus in north-eastern Italy. Results LST maps show the microclimatic characteristics peculiar to complex terrains, which would not be visible in maps commonly derived from interpolated meteorological station data. The patterns of the three indicator variables partially differ from each other, while winter temperature is the determining limiting factor for the distribution of Ae. albopictus. All three variables show a similar spatial pattern with some local differences, in particular in the northern part of the study area (upper Adige valley). Conclusions Reconstructed daily land surface temperature data from satellites can be used to predict areas of short term invasion of the tiger mosquito with sufficient accuracy (200 m pixel resolution size). Furthermore, they may be applied to other species of arthropod of medical interest for which temperature is a relevant limiting factor. The results indicate that, during the next few years, the tiger mosquito will probably spread toward northern latitudes and higher altitudes in north-eastern Italy, which will considerably expand the range of the current distribution of this species.</p
Trends in surface temperature from new long–term homogenized thermal data by applying remote sensing techniques and its validation using in-situ data of five southern European lakes
Full text linkRecent studies, based on a combination of long-term in-situ and satellite derived temperature data
indicate that lakes are rapidly warming at the global scale. Since Lake Surface Water Temperature
(LSWT) is highly responsive to long-term modifications in the thermal structure of lakes, it is a good
indicator of changes in lake characteristics. There have not been done many studies at a regional scale
to understand the lakes’ response to climate change, mainly due to lack of high spatio-temporal data.
Therefore, further studies are needed to understand variation in trends, impacts and consequences at
a regional scale. It is essential to have highly frequent spatially explicit data to understand the spatiotemporal
thermal variations of LSWT. Continuous in-situ water temperature data measured at high
temporal resolution from permanently installed stations are becoming increasingly available through
GLEON (Global Lake Ecological Observatory Network: http://gleon.org/) or NetLake (Networking
Lake Observatories in Europe). But these data are often heterogeneous with different sources and time
line, point based, and not available for many lakes around the globe. To establish permanent weather
stations for all the large lakes in the world is also not economically viable. As an alternative to direct
measurements, remote sensing is considered as a promising approach to reconstruct complete time
series of LSWT where direct measurements are missing. Temperature of land/water surfaces is one of
the direct and accurate measurements using satellite data acquired in the thermal infra-red spectral
region. Furthermore, the availability of daily satellite data since the 1980s at a moderate resolution
of 1 km from multiple polar orbiting satellites is an opportunity not to be missed. But owing to the
complexities related to earlier satellite missions, and the need of high level of processing, the potential
of the historical satellite data in deriving a homogenised LSWT is still not explored well.
There is a gap in the availability of long-term time series of LSWT from the satellite data which could
be used in understanding the patterns and drivers of thermal variations in large lakes. This thesis aims
to fill this gap by developing reproducible and extendable methods to derive homogenised daily LSWT
for thirty years from 1986 to 2015. Hence, the main objectives of this thesis are i) to reconstruct thirty
years (1986-2015) of daily satellite thermal data as a homogenised time series of LSWT for five large
Italian lakes by combining thermal data from multiple satellites, ii) to assess the quality of the satellite
derived LSWT using long-term in-situ data collected from the same lakes, iii) to report the seasonal
and annual trends in LSWT using robust statistical tests.
The first part of the thesis deals with the accurate processing of historical Advanced Along-Track
Scanning Radiometer (AVHRR) sensor data to derive time series of LSWT. A new method to resolve
the complex geometrical issues with the earlier AVHRR data obtained from National Oceanic and
Atmospheric Administration (NOAA) satellites has been developed. The new method can accurately
process historical AVHRR data and develop time series of geometrically aligned thermal channels in
the spectral range of 10.5-12.5 μm. The validation procedure to check the accuracy of image to image
co-registration using 2000 random images (from a total of 22,507 images) reported sub-pixel accuracy
with an overall Root Mean Square Error (RMSE) of 755.65 m. The usability of newly derived time
series of thermal channels to derive LSWT for lakes were tested and validated. Furthermore, crossplatform
and inter-platform validations were performed using corresponding same day observations
which reported an overall RMSE of less than 1.5 °C. In the second part of the thesis, a new method was developed to derive homogenised daily LSWT
standardized at 12:00 UTC from thermal channels of thirteen different satellites. The new method
is implemented for Lake Garda in Northern Italy developing time series of homogenised daily LSWT
for last thirty years from 1986 to 2015. The sensors used in this study are the AVHRR from multiple
NOAA satellites, Along Track Scanning Radiometer (ATSR) series from European Remote Sensing
(ERS) satellites and Moderate Resolution Imaging Spectroradiometer (MODIS) from Aqua and Terra
satellites. The LSWT time series are then validated using long-term in-situ data obtained from a deep
and a shallow sampling location in the lake. Validation of LSWT from individual satellites against
corresponding in-situ data reported an overall RMSE of 0.92 °C. The validation between final homogenised
LSWT and the in-situ data reported a coefficient of determination (R2) of 0.98 and a RMSE of 0.79 °C.
In the third part of the thesis, homogenised daily LSWT for the last thirty years (1986-2015) were
developed for five large lakes in Italy using the newly developed methods. The LSWT time series
was validated against the in-situ data collected from the respective lakes. Furthermore, long-term
trend analysis to study the seasonal and annual variations in LSWT over thirty years was performed
over the newly developed LSWT data. The validation procedure reported an average RMSE and
Mean Absolute Error (MAE) of 1.2 °C and 0.98 °C, respectively, over all the lakes. The trend analysis
reported an overall regional summer warming rate of 0.03 °C yr-1 and an annual warming rate of
0.017 °C yr-1. During summer, all studied sub-Alpine lakes showed high coherence in LSWT to each
other. The summer mean LSWT of Lake Garda, located in the sub-Alpine region also exhibit high
temporal coherence with that of central Italian Lake Trasimeno. Annually, mean LSWT of all subAlpine
lakes were found to be highly coherent to each other, while mean LSWT of Lake Trasimeno
resulted less coherent to the other lakes.
Overall, the thesis aims at contributing to the accurate processing of the various historical satellite data
and the development of a new method which allows to merge them into a unified, longest possible
time series of LSWT. The newly developed methods used open source geospatial software tools, which
ensure the reproducibility and also extensibility to any other geographic location given the availability
of satellite data. Although this study is using LSWT as the primary physical variable, the developed
methods can be used to derive any other time series of land and water based regional products from
satellite dat
Indicatori ecologici estratti da dati satellitari: high performance computing with GRASS GIS
No full textNews in GRASS GIS 7
Full text linkGRASS GIS, commonly referred to as GRASS (Geographic Resources Analysis Support System), is the free Geographic Information System (GIS) software with the longest record of development as FOSS4G community project. The increasing demand for a robust and modern analytical free GIS led to the start of GRASS GIS 7 development in April 2008. Since GRASS 6 more than 10,000 changes have been implemented with a series of new modules for vector network analysis, image processing, voxel analysis, time series management and improved graphical user interface (http://trac.osgeo.org/grass/wiki/Grass7/NewFeatures). The core system offers a new Python API and large file support for massive data analysis. Many modules have been undergone major optimization also in terms of speed. The presentation will highlight the advantages for users to migrate to the upcoming GRASS GIS 7 release
Freie Geo-Informationssysteme (FOSSGIS) für räumliche Analyse
No full textFreie Geo-Informationssysteme (FOSSGIS) stehen heute für qualitative Geodatenprozessierung von Raster- und Vektorkarten, innovative Fernerkundungsmethoden und Datenbankmanagement. FOSSGIS werden in räumlichen Analysen, Modellierung, für anspruchsvolle Visualisierung und WebGIS täglich von tausenden Nutzern verwendet. Interoperabilität und Aufbau gemeinsamer Software-Bibliotheken erlauben die Vernetzung zwischen den verschiedenen Softwareprodukten. Der Vortrag illustriert: Nutzungsmöglichkeiten freier Geo-Informationssysteme in der Archäologie bei der Integration heterogener Datenquellen, die Erhebung neuer Geodaten mit verschiedenen Fernerkundungsmethoden und Datenanalyse. Weiterhin werden Ausblicke auf die Verwaltung und Analyse von Geodaten-Zeitreihen gegeben
GRASS GIS e Sextante
No full textGRASS GIS has been integrated into Sextante as an extension. Sextante itself is commonly used within gvSIG. Through this integration, gvSIG users have access to the wealth of well tested algorithms provided by GRASS GIS
Spatio-temporal reconstruction of satellite-based temperature maps and their application to the prediction of tick and mosquito disease vector distribution in Northern Italy
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