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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Statistical Downscaling of Precipitation from Large-scale Atmospheric Circulation : Comparison of Methods and Climate Regions / Statistisk nedskalning av nederbörd från storskalig atmosfärscirkulation : Jämförelse mellan metoder och klimatregioner

Wetterhall, Fredrik January 2005 (has links)
A global climate change may have large impacts on water resources on regional and global scales. General circulation models (GCMs) are the most used tools to evaluate climate-change scenarios on a global scale. They are, however, insufficiently describing the effects at the local scale. This thesis evaluates different approaches of statistical downscaling of precipitation from large-scale circulation variables, both concerning the method performance and the optimum choice of predictor variables. The analogue downscaling method (AM) was found to work well as “benchmark” method in comparison to more complicated methods. AM was implemented using principal component analysis (PCA) and Teweles-Wobus Scores (TWS). Statistical properties of daily and monthly precipitation on a catchment in south-central Sweden, as well as daily precipitation in three catchments in China were acceptably downscaled. A regression method conditioning a weather generator (SDSM) as well as a fuzzy-rule based circulation-pattern classification method conditioning a stochastical precipitation model (MOFRBC) gave good results when applied on Swedish and Chinese catchments. Statistical downscaling with MOFRBC from GMC (HADAM3P) output improved the statistical properties as well as the intra-annual variation of precipitation. The studies show that temporal and areal settings of the predictor are important factors concerning the success of precipitation modelling. The MOFRCB and SDSM are generally performing better than the AM, and the best choice of method is depending on the purpose of the study. MOFRBC applied on output from a GCM future scenario indicates that the large-scale circulation will not be significantly affected. Adding humidity flux as predictor indicated an increased intensity both in extreme events and daily amounts in central and northern Sweden.
52

An assessment of uncertainties and limitations in simulating tropical cyclone climatology and future changes

Suzuki-Parker, Asuka 04 May 2011 (has links)
The recent elevated North Atlantic hurricane activity has generated considerable interests in the interaction between tropical cyclones (TCs) and climate change. The possible connection between TCs and the changing climate has been indicated by observational studies based on historical TC records; they indicate emerging trends in TC frequency and intensity in some TC basins, but the detection of trends has been hotly debated due to TC track data issues. Dynamical climate modeling has also been applied to the problem, but brings its own set of limitations owing to limited model resolution and uncertainties. The final goal of this study is to project the future changes of North Atlantic TC behavior with global warming for the next 50 years using the Nested Regional Climate Model (NRCM). Throughout the course of reaching this goal, various uncertainties and limitations in simulating TCs by the NRCM are identified and explored. First we examine the TC tracking algorithm to detect and track simulated TCs from model output. The criteria and thresholds used in the tracking algorithm control the simulated TC climatology, making it difficult to objectively assess the model's ability in simulating TC climatology. Existing tracking algorithms used by previous studies are surveyed and it is found that the criteria and thresholds are very diverse. Sensitivity of varying criteria and thresholds in TC tracking algorithm to simulated TC climatology is very high, especially with the intensity and duration thresholds. It is found that the commonly used criteria may not be strict enough to filter out intense extratropical systems and hybrid systems. We propose that a better distinction between TCs and other low-pressure systems can be achieved by adding the Cyclone Phase technique. Two sets of NRCM simulations are presented in this dissertation: One in the hindcasting mode, and the other with forcing from the Community Climate System Model (CCSM) to project into the future with global warming. Both of these simulations are assessed using the tracking algorithm with cyclone phase technique. The NRCM is run in a hindcasting mode for the global tropics in order to assess its ability to simulate the current observed TC climatology. It is found that the NRCM is capable of capturing the general spatial and temporal distributions of TCs, but tends to overproduce TCs particularly in the Northwest Pacific. The overpredction of TCs is associated with the overall convective tendency in the model added with an outstanding theory of wave energy accumulation leading to TC genesis. On the other hand, TC frequency in the tropical North Atlantic is under predicted due to the lack of moist African Easterly Waves. The importance of high-resolution is shown with the additional simulation with two-way nesting. The NRCM is then forced by the CCSM to project the future changes in North Atlantic TCs. An El Nino-like SST bias in the CCSM induced a high vertical wind shear in tropical North Atlantic, preventing TCs from forming in this region. A simple bias correction method is applied to remove this bias. The model projected an increase both in TC frequency and intensity owing to enhanced TC genesis in the main development region, where the model projects an increased favorability of large-scale environment for TC genesis. However, the model is not capable of explicitly simulating intense (Category 3-5) storms due to the limited model resolution. To extrapolate the prediction to intense storms, we propose a hybrid approach that combines the model results and a statistical modeling using extreme value theory. Specifically, the current observed TC intensity is statistically modeled with the General Pareto distribution, and the simulated intensity changes from the NRCM are applied to the statistical model to project the changes in intense storms. The results suggest that the occurrence of Category 5 storms may be increased by approximately 50% by 2055.
53

Improving Summer Drought Prediction in the Apalachicola-Chattahoochee- Flint River Basin with Empirical Downscaling

Dean, John Robert 16 July 2008 (has links)
The Georgia General Assembly, like many states, has enacted pre-defined, comprehensive, drought-mitigation apparatus, but they need rainfall outlooks. Global circulation models (GCMs) provide rainfall outlooks, but they are too spatially course for jurisdictional impact assessment. To wed these efforts, spatially averaged, time-smoothed, daily precipitation observations from the National Weather Service cooperative network are fitted to eight points of 700 mbar atmospheric data from the NCEP/NCAR Reanalysis Project for climate downscaling and drought prediction in the Apalachicola-Chattahoochee-Flint (ACF) river basin. The domain is regionalized with a factor analysis to create specialized models. All models complied well with mathematical assumptions, though the residuals were somewhat skewed and flattened. All models had an R-squared > 0.2. The models revealed map points to the south to be especially influential. A leave-one-out cross-validation showed the models to be unbiased with a percent error of < 20%. Atmospheric parameters are estimated for 2008–2011 with GCMs and empirical extrapolations. The transfer function was invoked on both these data sets for drought predictions. All models and data indicate drought especially for 2010 and especially in the south.
54

Climate model downscaling of Vancouver Island precipitation using a synoptic typing approach

Sobie, Stephen Randall 09 November 2010 (has links)
A statistical downscaling technique is employed to link atmospheric circulation produced by climate models at the large-scale to precipitation recorded at individual weather stations on Vancouver Island. Relationships between the different spatial scales are established with synoptic typing, coupled with non-homogeneous Markov models to simulate precipitation intensity and occurrence in historical and future periods. Types are generated through a clustering algorithm which processes daily precipitation observations recorded by Environment Canada weather stations spanning 1971 to 2000. Large-scale atmospheric circulation data is taken from an ensemble of climate model projections made under the IPCC AR4 SRES A2 scenario through the end of the 21st century. Atmospheric predictors used to influence the Markov model are derived from two versions of the data: Averages of model grid cells selected by correlation maps of circulation and precipitation data; a new approach involving Common Empirical Orthogonal Functions (EOFs) calculated from model output over the Northeast Pacific Ocean. Circulation-based predictors capture the role of sea level pressure (SLP), and winds in influencing coastal precipitation over Vancouver Island. The magnitude and spatial distribution of the projected differences are dependent on the predictors used. Projections for 2081 to 2100 made using common EOFs result in most stations reporting no statistically significant change compared to the baseline period (1971 to 2000) in both seasons. Projections using averaged grid cells find winter season (Nov-Feb) precipitation anomalies produce values that are modestly positive, with typical gains of 6.5% in average precipitation, typical increases of 7.5% rising up to 15% in extreme precipitation, and little spatial dependence. In contrast, average and extreme summer precipitation intensity (Jun-Sep) declines negligibly at most island weather stations with the exception of those on the southern and western sections, which experience reductions of up to 20% relative to the latter thirty years of the twentieth century. Precipitation occurrence decreases slightly in both seasons at all stations with declines in the total days with measurable precipitation ranging from 2% to 8% with reductions also seen in the length of extended periods of precipitation in both seasons.
55

Hydroclimatic variability and the integration of renewable energy in Europe : multiscale evaluation of the supply-demand balance for various energy sources and mixes / Variabilité hydro-climatique et intégration d'énergies renouvelables en Europe : analyse multi-échelle de l'équilibre production-demande pour différentes sources et combinaisons d'énergies

Raynaud, Damien 08 December 2016 (has links)
Dans un contexte de changement climatique, l'intégration des énergies renouvelables aux systèmes électriques est un enjeu majeur des décennies à venir. Les énergies liées au climat (photovoltaïque, éolien et hydro-électricité) peuvent contribuer à une réduction des émissions de gaz à effet de serre. Cependant, elles sont fortement intermittentes et la production électrique associée peine à répondre à la demande.Cette étude vise à évaluer la faisabilité météorologique du développement d'un système de production électrique basé sur les sources d'énergie liées au climat (CRE - Climate-Related Energy). Nous considérons uniquement leurs variations spatiotemporelles et supposons un équilibre entre production et demande moyennes. Nous avons développé CRE-Mix, une chaîne de modèles permettant de convertir les variables météorologiques en chroniques énergétiques. Cet outil permet l'estimation des fluctuations spatiotemporelles de production et de demande énergétiques résultant de la variabilité hydro-climatique. Pour une sélection de régions en Europe, nous évaluons la facilité d'intégration des CRE en fonctions de leur cohérence temporelle avec la demande. Pour chaque source d'énergie et de multiples mix énergétiques nous estimons successivement (i) le taux de pénétration moyen (PE), qui quantifie la proportion de demande satisfaite sur une longue période et (ii) les caractéristiques des périodes de faible pénétration pour lesquelles le taux journalier de demande satisfaite reste bas pendant plusieurs jours consécutifs. Les résultats montrent que les systèmes basés sur une seule source ont du mal à répondre à la demande et souffrent de longues périodes de faible PE, en raison de leur variabilité temporelle. Cependant, une combinaison d'énergies, l'utilisation de systèmes de stockage ou l'échange d'énergie entre régions, permettent d'augmenter fortement la fiabilité des CRE (PE proche de 100% et rares/courtes périodes de faible pénétration). Cette étude, basée sur 30 ans, a été étendue à l'ensemble de XXème siècle afin d'évaluer les fluctuations basse fréquence des CRE résultant de la variabilité interne du climat. De longues chroniques régionales de production et de demande ont été générées grâce au développement d'une méthode de descente d'échelle statistique basée sur les analogues atmosphériques (SCAMP). Cet outil génère des scénarios météorologiques multivariés physiquement cohérents. Les résultats montrent que les variations basse fréquence des CRE sont influencées par les grandes oscillations océano-climatiques. De plus, on montre que les variations multi-décennales de l'hydro-électricité sont particulièrement importantes avec notamment une différence en PE supérieure à 15% d'une décade à l'autre et des périodes de faible pénétration aux caractéristiques très irrégulières.Enfin, nous évaluons la pertinence de systèmes électriques basés sur les CRE en climat futur. SCAMP permet de produire des scénarios régionaux de variables météorologiques à partir des modèles climatiques issus des simulations CMPI5. Pour les précipitations, les tendances simulées par SCAMP sont en désaccord avec de nombreuses études. L'application de SCAMP en "modèle parfait" semble indiquer que le lien entre les situations atmosphériques de grande échelle et les précipitations totales, mais également convectives et stratiformes, change en climat futur. / In the context of climate change, the integration of renewables in electric power systems is one of the main challenges of the coming decades. Climate-Related-Energy sources (CRE - solar, wind and hydro power) can contribute to reduce the greenhouse gas emissions. However, they exhibit large spatio-temporal fluctuations and the associated intermittent electricity generation often leads to an incomplete supply-demand balance. This study aims to evaluate the meteorological feasibility of developing an electric power system that would only rely on CRE sources. We focus on the multi-scale spatio-temporal fluctuations of these renewables by assuming a balance between mean electricity production and mean energy load. We develop and use CRE-mix, a suite of models able to convert meteorological conditions into CRE time series. It gives an assessment the spatio-temporal fluctuations of power production and energy demand, resulting from the multi-scale hydro-climatic variability. For a set of European regions, we assess the ease of integration of CRE sources, regarding their temporal consistency with energy demand. For each CRE source and multiple CRE mixes, we consider in turn (i) the mean penetration rate (PE), which quantifies the proportion of satisfied demand over a long period and (ii) the characteristics of low penetration periods, defined as sequences of days for which the penetration rate is lower than a given threshold. This study proves that single CRE sources have difficulty to meet the energy demand and suffer from long low penetration periods, due to their multi-scale temporal variations. However, using some integrating factors (multi-sources, storage systems, inter-regions electric power transmission), efficiently improves the reliability of CRE-based power systems with PE rates close to 100% and rare low penetration periods.These analyses, based on a 30-yr period, are extended to the entire 20th century in order to assess the low frequency fluctuations of CRE sources resulting from the internal variability of climate. Long regional series of production and demand, were generated thanks to the development of a statistical downscaling method based on atmospheric analogues (SCAMP). It simulates physically-consistent multivariate series of meteorological parameters. The results demonstrate that these fluctuations are related to some large scale oceano-climatic oscillations. Moreover, the multi-decennial variations of hydro power are particularly large: changes in PE rates exceeding 15% from one decade to the other and uneven energy droughts characteristics.Finally, we evaluate the relevance of the CRE sources under future climate conditions. SCAMP is used to produce downscaled projections of meteorological drivers of CRE sources for the 21st century from a selection of CMIP5 climate models. The resulting scenarios for precipitation are not consistent with other studies focusing of the future modifications of this variable in Europe. The application of SCAMP in a perfect-model approach seems to indicate that the large-scale-meteorology/local-precipitation relationship is changing in the course of the 21st century, for all total, convective and stratiform precipitation.
56

Suivi et modélisation du bilan de masse de la calotte Cook aux iles Kerguelen. Lien avec le changement climatique / Monitoring and modelling of the mass balance of the Cook Ice Cap, Kerguelen Islands - link with climate change

Verfaillie, Deborah 24 November 2014 (has links)
Les glaciers des régions sub-polaires entre 45 et 60°S ont reculé dramatiquement au cours du dernier siècle. L'archipel des Kerguelen (49°S, 69°E) constitue un site unique dans ces régions où peu d'observations sont disponibles pour comprendre le recul glaciaire. Situés à faible altitude et proches de l'océan, ses glaciers ont montré une sensibilité particulière aux variations atmosphériques et océaniques. Ainsi, depuis les années 60, la calotte Cook (~400 km2) a reculé de manière spectaculaire, perdant 20% de sa surface en 40 ans. L'objectif de mon travail de thèse était d'évaluer l'état actuel et futur de la calotte, et de comprendre les causes de ce recul tout en les replaçant dans un contexte global. Pour ce faire, un réseau météorologique et glaciologique a été mis en place en 2010 sur l'archipel et des campagnes de mesures ont depuis été réalisées annuellement. L'analyse de ces mesures nous permet de confirmer le bilan de masse négatif de la calotte. Parallèlement, l'étude de l'albédo de l'ensemble de la calotte Cook à partir d'images satellites MODIS (MODerate resolution Imaging Spectroradiometer) permet d'évaluer l'évolution de la ligne de neige de la calotte depuis 2000, mettant en évidence une réduction importante de sa zone d'accumulation au cours des dix dernières années. La modélisation du bilan de masse de la calotte Cook à l'aide d'un modèle degré-jour couplé à une routine dynamique révèle par ailleurs que son retrait est principalement dû à une forte diminution des précipitations sur l'archipel depuis les années 60. Afin de replacer le recul des glaciers aux îles Kerguelen dans un contexte global, les tendances climatiques sur l'ensemble des zones subpolaires sont étudiées, faisant apparaître que la zone sub-Antarctique est actuellement celle où les retraits sont les plus forts à l'échelle du globe. Pour comprendre ces variations, nous analysons un ensemble complet de jeux d'observations de terrain, de satellites et de résultats de modélisation : réanalyses, modèles de l'exercice CMIP5 (Coupled Model Intercomparison Project phase 5), observations de température atmosphérique et océanique, précipitations, etc. Ceux-ci révèlent un réchauffement et un assèchement quasi généralisé de l'ensemble de la zone 40-60° S, lié à un déplacement vers le sud des zones dépressionnaires en réponse aux phases de plus en plus fréquemment positives du mode annulaire austral (Southern Annular Mode, SAM). Le recul récent des glaciers des îles Kerguelen, mais également d'autres zones glaciaires des régions subpolaires de l'hémisphère sud, est donc principalement lié à un déficit d'accumulation causé par le SAM, et amplifié par le réchauffement atmosphérique. L'évolution future du bilan de masse de la calotte Cook aux îles Kerguelen est évaluée grâce au Modèle Atmosphérique Régional (MAR), forcé à ses frontières par les modèles de l'exercice CMIP5. Des simulations du bilan de masse récent sont d'abord effectuées sur base des réanalyses ERA-Interim et NCEP1, et comparées aux observations in situ. Parallèlement, des simulations d'un an sont réalisées avec le désagrégateur de précipitations SMHiL (Surface Mass balance High resolution downscaLing) en sortie du MAR, à différentes échelles, afin d'évaluer l'impact du changement d'échelle sur la représentation des précipitations. Une évaluation des modèles CMIP5 par rapport à ERA-Interim sur la période récente est ensuite réalisée sur base de certaines variables climatiques-clé. Le modèle le plus proche d'ERA-Interim sur la période récente, et les deux modèles les plus extrêmes sont ensuite utilisés pour forcer le MAR sur le prochain siècle, et les sorties de bilan de masse de surface sont analysées de manière critique. L'analyse du retrait de la calotte des îles Kerguelen à l'aide de différents outils a permis de mieux comprendre le lien entre glaciers et climat, mettant en évidence le rôle majeur du SAM, mais a également soulevé de nouvelles questions. / Glaciers of the southern hemisphere sub-polar regions between 45 and 60°S have declined dramatically over the last century. The islands of Kerguelen archipelago (49°S, 69°E) represent a unique location in regions where few data are available to understand glacier retreat. Situated at low altitudes and close to the ocean, their glaciers have shown particular sensitivity to atmospheric and oceanic variations. Thus, since the 1960s, the Cook Ice Cap (~400km2) has retreated spectacularly, losing 20% of its area in 40 years. The aim of my thesis was to assess the present and future state of the ice cap, and to understand the causes of this decline while putting them in a global context. To do so, a meteorological and glaciological network was set up in 2010 on Kerguelen archipelago and field campaigns have been carried out annually since then. Analysis of these measurements confirms the negative mass balance of Cook Ice Cap. In parallel, the study of the albedo over the whole ice cap from MODIS satellite images (MODerate resolution Imaging Spectroradiometer) gives us access to the evolution of the snow line since 2000, highlighting an important reduction of Cook Ice Cap accumulation area over the last decade. Mass balance modelling of the Cook Ice Cap using a degree-day model coupled to a simple ice motion routine further reveals that its retreat is mainly due to a strong decrease in precipitation over the Kerguelen Islands since the 1960s. In order to put the decline of the cryosphere on Kerguelen in a global context, climatic trends over the whole sub-polar regions are studied, revealing that the sub-Antarctic area is currently the one where glacier retreat is the strongest. To understand these variations, we analyse a complete set of field and satellite observations and modelling results : reanalyses, models from the CMIP5 (Coupled Model Intercomparison Project phase 5) experiment, atmospheric and oceanic temperature and precipitation observations, etc. The latter show warming and quasigeneralised drying of the whole 40-60°S area, linked to the southward shift of storm tracks in response to the more frequent positive phases of the Southern Annual Mode (SAM). Recent glacier retreat on Kerguelen archipelago, and for other glaciers and ice caps located at similar latitudes, is thus mainly due to a deficit of accumulation caused by the SAM, and amplified by atmospheric warming. The future evolution of Cook Ice Cap mass balance is evaluated using the MAR (Modèle Atmosphérique Régional) model, forced at its boundaries by CMIP5 models. Recent mass balance simulations are first carried out using ERA-Interim and NCEP1 reanalyses, and compared to in situ observations. In parallel, one-year simulations are produced with the precipitation desagregation scheme SMHiL (Surface Mass balance High resolution downscaLing) on MAR outputs, at various scales, in order to evaluate the impact of downscaling on precipitation. An evaluation of CMIP5 models over the recent period against ERA-Interim is then carried out, considering certain key climatic variables. The model closest to ERA-Interim as well as the two most extreme models are then used to force the MAR model over the next century, and surface mass balance outputs are critically analysed. The analysis of the decline of the Kerguelen ice cap using different tools and techniques brought new insights on the link between glaciers and climate, highlighting the major role of the SAM, but also raised new questions.
57

Intérêts de la méthode des analogues pour la génération de scénarios de précipitations à l'échelle de la France métropolitaine : Cohérence spatiale et adaptabilité du lien d'échelle / Interests of the analog method for the generation of precipitation scenarios for the French territory : Spatial consistency and adaptability of the scale relation.

Chardon, Jérémy 11 December 2014 (has links)
Les scénarios hydrologiques requis pour les études d'impacts hydrologiques nécessitent de disposer de scénarios météorologiques non biaisés et qui soient de surcroît adaptés aux échelles spatiales et temporelles des hydro-systèmes considérés. Les scénarios météorologiques obtenus en sortie brute des modèles de climat et/ou des modèles de prévision numérique du temps sont de ce fait non appropriées. Les sorties de ces modèles sont par suite souvent adaptées à l'aide de Méthodes de Descente d'Echelle Statistique (MDES). Depuis les années 2000, les MDES ont beaucoup été utilisées pour la génération de scénarios météorologiques en un site. En revanche, la génération de scénarios spatiaux couvrant de larges territoires est une tâche plus difficile, en particulier lorsque l'on souhaite respecter la cohérence spatiale des précipitations à prédire. Parmi les MDES usuelles, les approches basées sur la recherche de situations analogues passées permettent de satisfaire cette contrainte. Dans cette thèse, nous évaluons la capacité d'un Modèle Analog (MA) – où l'analogie porte sur les géopotentiels 1 000 et 500 hPa – pour la génération de scénarios de précipitation spatialement cohérents pour le territoire Français métropolitain. Dans un premier temps, la transposition spatiale du modèle MA est évaluée : le modèle s'avère utilisable pour la génération de scénarios spatiaux cohérents sur des territoires couvrant plusieurs dizaines de milliers de kilomètres carrés dès lors qu'aucune barrière climatique n'est rencontrée. Dans un second temps, nous évaluons la sensibilité des performances de prédiction à l'agrégation spatiale de la variable à prédire. L'augmentation de performance avec l'agrégation s'explique alors par la diminution de la variabilité du prédictand, pour autant que les variables de grande échelle considérées soient de bons prédicteurs pour la région considérée. Dans une dernière étude, nous explorons la possibilité d'améliorer la performance locale du modèle analogue par l'ajout de prédicteurs locaux. Le modèle combiné qui en résulte permet d'accroître sensiblement les performances de prédiction par l'adaptation du lien d'échelle sur la base d'un jeu de prédicteurs additionnels. Il apparaît de plus que la pertinence de ces prédicteurs dépend de la situation de grande échelle rencontrée ainsi que de la région considérée. / Hydrological scenarios required for the impact studies need to have unbiased meteorological scenarios adapted to the space and time scales of the considered hydro-systems. Hence, meteorological scenarios obtained from global climate models and/or numerical weather prediction models are not really appropriated. Outputs of these models have to be post-processed, which is often carried out thanks to Statistical Downscaling Methods (SDMs). Since the 2000's, SDMs are widely used for the generation of scenarios at a single site. The generation of relevant precipitation fields over large regions or hydro-systems is conversely not straightforward, in particular when the spatial consistency has to be satisfied. One strategy to fulfill this constraint is to use a SDM based on the search of past analog situations. In this PhD, we evaluate the ability of an Analog Model (AM) – where the analogy is applied to the geopotential heights 1000 and 500 hPa – for the generation of spatially coherent precipitation scenarios over the French metropolitan territory. In a first part, the spatial transferability of an AM is evaluated: the model appears to be usable for the generation of spatial coherent scenarios over territories covering several tens of thousands squared kilometers if no climatological barrier is met in between. In a second part, we evaluate the sensitivity of the prediction performance to the spatial aggregation of the predictand. The performance increases with the aggregation level as long as the large scale variables are good predictors of precipitation for the region under consideration. This performance increase has to be related to the decrease of the predictand variability. We finally explore the possibility of improving the local performance of the AM using additional local scale predictors. For each prediction day, the prediction is obtained from a parametric regression model, for which predictors and parameters are estimated from the analog dates. The resulting combined model noticeably allows increasing the prediction performance by adapting the downscaling link for each prediction day. The selected predictors for a given prediction depend on the large scale situation and on the considered region.
58

Climate Change and Its Effects on the Energy-Water Nexus

Wang, Yaoping January 2018 (has links)
No description available.
59

Downscaling the Doughnut Economics Model - Employing a Global Model at the Enterprise Level: A case study of Proton Group and Apotea AB

Hmeidi, Jad, Ryberg, Adrian January 2023 (has links)
In a rapidly changing world, sustainability is becoming more and more of a priority for organizations. This paper evaluates the possibility of using the Doughnut Economics Model (DEM) as a tool to implement sustainability within an organization on the firm-level, highlighting the potential opportunities and limitations that it poses. Through case studies conducted with two organizations (Apotea AB &amp; Proton Group), both common and firm-specific gaps within sustainability strategies are identified, and the applicability of the DEM is appraised as a tool to help fill these gaps. A qualitative research method was employed, and interviews were held with sustainability managers from Apotea AB and Proton Group. A qualitative thematic analysis process led to the generation of initial codes, themes, and patterns that emerged throughout the interviews held. The results from this study highlighted the illustrative and visual nature of the DEM, and how it could help firms view sustainability from different perspectives. The visualisation of the model helps stimulate conversations about sustainability within the firm, and raising awareness on the topic of sustainability, promoting it within organizational culture. This study additionally concluded that the implementation of the DEM in only a firm-specific, directly impacted area, could help the firm with pinpointing niche areas where the enterprise can make its largest contribution towards a safe and just space for humanity. On the other hand, this study found and supported existing claims through past research on the model’s limitations in terms of its downscaling, as the planetary boundaries are designed for a global scale. Moreover, the model lacks in defining policies, indicators, or measurements regarding areas of improvement. The opportunities that lie in the DEM are plentiful, however, the downscaling process on a firm-scale is extremely challenging, and little-to-no existing research or literature exists on the topic.
60

Combining Multiband Remote Sensing and Hierarchical Distance Sampling to Establish Drivers of Bird Abundance

Richter, Ronny, Heim, Arend, Heim, Wieland, Kamp, Johannes, Vohland, Michael 11 April 2023 (has links)
Information on habitat preferences is critical for the successful conservation of endangered species. For many species, especially those living in remote areas, we currently lack this information. Time and financial resources to analyze habitat use are limited. We aimed to develop a method to describe habitat preferences based on a combination of bird surveys with remotely sensed fine-scale land cover maps. We created a blended multiband remote sensing product from SPOT 6 and Landsat 8 data with a high spatial resolution. We surveyed populations of three bird species (Yellow-breasted Bunting Emberiza aureola, Ochre-rumped Bunting Emberiza yessoensis, and Black-faced Bunting Emberiza spodocephala) at a study site in the Russian Far East using hierarchical distance sampling, a survey method that allows to correct for varying detection probability. Combining the bird survey data and land cover variables from the remote sensing product allowed us to model population density as a function of environmental variables. We found that even small-scale land cover characteristics were predictable using remote sensing data with sufficient accuracy. The overall classification accuracy with pansharpened SPOT 6 data alone amounted to 71.3%. Higher accuracies were reached via the additional integration of SWIR bands (overall accuracy = 73.21%), especially for complex small-scale land cover types such as shrubby areas. This helped to reach a high accuracy in the habitat models. Abundances of the three studied bird species were closely linked to the proportion of wetland, willow shrubs, and habitat heterogeneity. Habitat requirements and population sizes of species of interest are valuable information for stakeholders and decision-makers to maximize the potential success of habitat management measures.

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