1,721,002 research outputs found
MONITORAGGIO E VALUTAZIONE DELL'IMPATTO DELLE ATTIVITÀ UMANE SULL'ECO-AMBIENTE BASATO SUL TELERILEVAMENTO - Osservazione congiunta di satelliti diurni e notturni
Get PDFA partire dalla rivoluzione industriale, la rapida crescita della popolazione globale e gli intensi processi di urbanizzazione hanno portato a un eccessivo sfruttamento delle risorse naturali e hanno rimodellato la superficie terrestre. Secondo il rapporto IPCC Climate Change 2021, le attività umane hanno causato un riscaldamento globale: il sistema climatico ha sperimentato cambiamenti diffusi e rapidi, e la probabilità di eventi meteorologici estremi composti è aumentata notevolmente. Pertanto, il monitoraggio tempestivo delle attività umane e dell'ambiente naturale è di grande importanza per lo sviluppo sostenibile della società. Poiché ci sono diverse limitazioni alle soluzioni di monitoraggio a terra comunemente usate, le piattaforme di telerilevamento, che possono ottenere rapidamente informazioni regionali e persino globali sui processi di superficie, sono diventate uno strumento essenziale per le osservazioni della terra. Così, questa tesi mira ad esplorare l'integrazione del telerilevamento diurno e notturno per tracciare le dinamiche delle impronte delle attività umane e dell'eco-ambiente, e per valutare quantitativamente le interazioni tra loro: tutti questo è di grande importanza per la promozione degli Obiettivi di Sviluppo Sostenibile. Per raggiungere questo obiettivo, è stata implementata una serie di attività di ricerca sia nell'elaborazione dei dati che nell'esplorazione delle applicazioni. In primo luogo, sono stati sviluppati i modelli di calibrazione per i fenomeni di saturazione e turbolenza interannuale presenti nei dati NTL. In secondo luogo, è stato proposto un metodo basato sui dati più avanzati di Black Marble Suite, per le immagini mensili NTL composte in tempo quasi reale, il quale ha fornito un importante supporto per il rilevamento degli effetti degli eventi a breve termine. Inoltre, sono stati prodotti e resi open source i livelli di riferimento di qualità per i dati ENTL, attualmente molto utilizzati . Infine, le attività umane e le dinamiche ecoambientali a scala locale, regionale e globale sono state valutate e discusse attraverso i dati NTL e i modelli RSEI. Anche se questi lavori meritano di essere avanzati e raffinati, i risultati riportati in questa tesi hanno portato ad alcune nuove scoperte intellettuali. Alcuni dei modelli e dei prodotti di dati sviluppati nella tesi sono stati applicati da altri studiosi a studi regionali in diversi contesti, il che è incoraggiante. In conclusione, il lavoro in questa tesi espande la prospettiva dell'osservazione della Terra e dà un contributo positivo per aiutarci a capire le interazioni uomo-ambiente in modo più preciso.Since the Industrial Revolution, rapid global population growth and intense urbanization processes have led to overexploitation of natural resources and reshaped the land surface. According to the IPCC Climate Change 2021 report, human activities have caused global warming, the climate system has experienced widespread and rapid changes, and the probability of compound extreme weather events increased significantly. Therefore, timely monitoring of human activities and the natural environment is of great importance to the sustainable development of human society. Since there are several limitations to the commonly used ground-based monitoring solutions, remote sensing platforms, which can quickly obtain regional and even global information on surface processes, have become an essential tool for Earth observations. Thus, this thesis aims to explore the integration of daytime and nighttime remote sensing to track the dynamics of human activity footprints and eco-environment, and to quantitatively assess the interactions between them, which is valuable for promoting SDGs. To achieve this objective, a series of efforts both in data processing and application exploration were implemented. First, the calibration models for saturation phenomena and interannual turbulence present in NTL data were developed. Second, based on the most advanced Black Marble Suite data, a method for near real-time composited monthly NTL images was proposed, which provided an important support for short-term period event effect detection. In addition, the quality flag layers for the widely used ENTL data today have been produced and open sourced. Finally, human activities and eco-environmental dynamics at local, regional and global scales were assessed and discussed through NTL data and RSEI models. Although these efforts deserve to be advanced and refined, the works in this thesis has led to some new intellectual discoveries. Some of the models and data products developed in the thesis have been applied by other scholars to regional studies in different contexts, which is encouraging. In conclusion, the work in this thesis expands the perspective of Earth observation and makes a positive contribution to help us understand human-environment interactions more precisely
Instability of remote sensing based ecological index (RSEI) and its improvement for time series analysis
No full textWith the rapid development of remote sensing technology, the monitoring of land surface ecological status (LSES) based on remote sensing has made remarkable progress, which has a positive contribution on improving the regional ecological environment and promoting the realization of Sustainable Development Goals (SDGs). Among them, the proposed Remote Sensing-based Ecological Index (RSEI) becomes the most widely used model in the current application of remote sensing-based LSES monitoring due to its complete derived from remote sensing images and no subjective intervention. RSEI is not flawless either, and it still suffers from some uncertainties in its application in multiple scenarios. However, compared to the extensive applied research, work on the instability assessment and improvement of RSEI is particularly scarce and urgently needed. Therefore, in this paper, we analyzed the possible instabilities in the RSEI calculation process and proposed various inversion models to evaluate their accuracy and stability in time-series LSES monitoring. The results indicated that the existing normalized RSEI is relatively stable for the characterization of single-phase LSES, however, there is a high risk in the time-series analysis or cross-regional comparison due to the interference of component extremes. The standard deviation discretized DRSEIs proposed in this paper perform better in both single-phase and long-term dynamics LSES assessments and are more consistent with the real land cover changes. Also, compared with the approach that measures LSES dynamics using time-series regional RSEI mean values, the DRSEIs change detection results can reveal the spatial heterogeneity of regional LSES dynamics more effectively and provide a finer reference for the formulation and implementation of ecological protection policies
Spatial Variation of NO2 and Its Impact Factors in China: An Application of Sentinel-5P Products
Get PDFAs an important tropospheric trace gas and precursor of photochemical smog, the accumulation of NO2 will cause serious air pollution. China, as the largest developing country in the world, has experienced a large amount of NO2 emissions in recent decades due to the rapid economic growth. Compared with the traditional air pollution monitoring technology, the rapid development of the remote sensing monitoring method of atmospheric satellite has gradually become the critical technical means of global atmospheric environmental monitoring. To reveal the NO2 pollution situation in China, based on the latest NO2 products from Sentinel-5P TROPOMI, the spatial–temporal characteristics and impact factors of troposphere NO2 column concentration of mainland China in the past year (February 2018 to January 2019) were analyzed on two administrative levels for the first time. Results show that the monthly fluctuation of tropospheric NO2 column concentration has obvious characteristics of “high in winter and low in summer”, while the spatial distribution forms a “high in East and low in west” pattern, bounded by Hu Line. The comparison of Coefficient of Variation (CV) and spatial autocorrelation models at two kinds of administrative scales indicates that although the spatial heterogeneity of NO2 column concentration is less affected by the observed scale, there is a “delayed effect” of about one month in the process of NO2 column concentration fluctuation. Besides, the impact factors analysis based on Spatial Lag Model (SLM) and Geographic Weighted Regression (GWR) reveals that there is a positive correlation between nighttime light intensity, the secondary and tertiary industries proportion and NO2 column concentration. Furthermore, for regions with serious NO2 pollution in North China Plain, the whole society electricity consumption and vehicle ownership also play a positive role in increasing the NO2 column concentration. This study will enlighten the government and policy makers to formulate policies tailored to local conditions, to more effectively implement NO2 emission reduction and air pollution prevention
Spatial heterogeneity of the thermal environment based on the urban expansion of natural cities using open data in Guangzhou, China
No full textThe change in the urban thermal environment resulting from urban expansion is attracting increasing attention from researchers. In this research, the influence of the urban expansion process on the spatial heterogeneity of the thermal environment was analyzed, including quantitative research on urban expansion based on the natural city (NC) concept using open data and the footprint of the thermal environment (TE FP) model to reveal the influences in different time periods between 2014 and 2018 in Guangzhou, China. And the TE FP is an indication used to evaluate whether certain area is affected by the thermal environment of the NC. The results demonstrated the following. (1) The high-temperature area in Guangzhou was 2293.55 km2 in 2014, 2330.24 km2 in 2016, and 2609.81 km2 in 2018 and expanded by 1.60% (2014–2016), 12.00% (2016–2018) and 13.79% (2014–2018), respectively. (2) The urban area increased from 182.10 km2 in 2014 to 266.90 km2 in 2018, which represented an increase by almost half, with an average annual expansion rate of 10.03%. (3) In 2014, 2016 and 2018, the area representing the TE FP consisted of the areas of five buffer zones, six buffer zones and eight buffer zones, respectively. This study provides a new approach to the study of urban expansion and a new perspective for exploring the influence of the urban expansion process on the spatial heterogeneity of the thermal environment
Monitoring and analysis of China’s integrated city development based on remote sensing: a case study of Guangfo city
No full text: Regional synergy is seen as an advanced form of coordinating the social economy and maintaining competitiveness in today's global competition system. Since China's reform and development, under the background of rapid urbanization and regional coordinated development, cities with geographical proximity and close economic and social ties have gradually formed a new mode of urban development, which is called integrated city. As a new phenomenon in the process of China’s urbanization, the existing research mainly focuses on the typical case studies, and the research methods are mostly limited to literature review and theoretical analysis. Therefore, in this paper, the Guangfo City which is the most representative integrated citiy in China was selected as the research objectives. Based on multi-spectral Landsat 8 and nighttime light NPP/VIIRS images, landuse conversion, block light fluctuation and light gravity center migration in the transitional zone of the integrated cities were analyzed respectively. The results show that there is significant spatial heterogeneity in the integration level of Guangfo City’s development. Moreover, the coupling analysis of nighttime light and urban expansion in the boundary zone shows that the enhancement effect of construction land expansion on nighttime light is expanding with the development of integration, and the inhibition effect of vegetation cover on nighttime light intensity is weakening. Our application results expand the data sources of integrated city research and the obtained results can potentially support the decision-making and planning in the process of urban development
A single-channel 5.5mW 3.3GS/s 6b fully dynamic pipelined ADC with post-amplification residue generation
No full text
Modeling Polycentric Urbanization Using Multisource Big Geospatial Data
Get PDFUnderstanding the dynamics of polycentric urbanization is important for urban studies and management. This paper proposes an analytical model that uses multisource big geospatial data to characterize such dynamics to facilitate policy making. There are four main steps: (1) main centers and subcenters are identified using spatial cluster analysis and geographically weighted regression (GWR) based on Visible Infrared Imaging Radiometer Suite (VIIRS)/NPP and social media check-in data; (2) the built-up areas are extracted by using Defense Meteorological Satellite Program—Operational Linescan System (DMSP/OLS) gradient images; (3) the economic corridors that connect the main center and subcenters are constructed using road network data from Open Street Map (OSM) with the least-cost distance method; and (4) the major urban development direction is identified by analyzing the changes in built-up areas within the economic corridors. The model is applied to three major cities in northeastern, central, and northwestern China (Shenyang, Wuhan, and Xi’an) from 1992 to 2012
The desaturation method of DMSP/OLS nighttime light data based on vector data: taking the rapidly urbanized China as an example
No full textThe saturation of night light data caused by sensor defects conceals the differences and details of light luminance in the urban area, which greatly limits the application of Nighttime Light (NTL) in the study of urbanization. Although some methods have been proposed to mitigate the saturation of NTL data, the research of desaturation is worth further advancing due to its shortcomings in highlighting light differences and spatial resolution. Therefore, we propose a new spectral index, the Vector Data Adjusted NTL Index (VDANTLI) after analyzing the influence of different auxiliary parameters on saturation elimination. Then, we select the three most developed urban agglomerations in China and make a series of qualitative and quantitative analysis. The results of various assessments confirm that VDANTLI can effectively alleviate NTL saturation and enhance urban lighting differences. Moreover, by dynamically adjusting the length of the grid and single-phase vector data modified time-series NTL data, we further achieve the resolution-series and time-series VDANTLI. Therefore, compared with previous desaturation models, the VDANTLI can be used as an effective indicator and even an indispensable basic data for urbanization research and socio-economic spatial analysis because of its unique advantages in spatial resolution and the capability in time-series native NTL desaturation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
