Phenological events in temperate forests, such as bud burst and senescence, exert strong control over seasonal fluxes of water, energy and carbon. The timing of these transitions is influenced primarily by air temperature and photoperiod, although the exact nature and magnitude of these controls is poorly understood. In this dissertation, I use in situ and remotely sensed observations of phenology in combination with surface meteorological data and measurements of biosphere-atmosphere carbon exchanges to improve understanding and develop models of canopy phenology in temperate forest ecosystems. In the first element of this research I use surface air temperatures and eddy covariance measurements of carbon dioxide fluxes to evaluate and refine widely used approaches for predicting the onset of photosynthesis in spring that account for geographic variation in thermal and photoperiod constraints on phenology. Results from this analysis show that the refined models predict the onset of spring photosynthetic activity with significantly higher accuracy than existing models. A key challenge in developing and testing these models, however, is lack of adequate data sets that characterize phenology over large areas at multi-decadal time scales. To address this need, I develop a new method for estimating long-term average and interannual dynamics in the phenology of temperate forests using time series of Landsat TM/ETM+ images. Results show that estimated spring and autumn transition dates agree closely with in-situ measurements and that Landsat-derived estimates for the start and end of the growing season in Southern New England varied by as much as 4 weeks over the 30-year record of Landsat images. In the final element of this dissertation, I use meteorological data, species composition maps, satellite remote sensing, and ground observations to develop models of springtime leaf onset in temperate deciduous forests that account for geographic differences in how forest communities respond to springtime climate forcing. Results demonstrate important differences in cumulative heating requirements and photoperiod cues among forest types and that regional differences in species composition explain substantial geographic variation in springtime phenology of temperate forests. Together, the results from this dissertation provide an improved basis for observing and modeling springtime phenology in temperate forests.

In this dissertation, I explore the relationship between water management, urbanism, and socio-political organization at the Classic Maya site of Xultun, Guatemala. In an area without permanent surface water, provisioning and maintenance of large stores of water was a necessity for agricultural stability. Combining evidence from archaeological survey, excavation, remote sensing, and geospatial analysis I demonstrate that settlement at Xultun was organized topographically. Elite ritual structures were concentrated on the highest areas, and in proximity to reservoirs. This gave leaders control over the release of water, and by extension control over their subjects. Xultun was built on a natural hill. Urban space was concentrated into three topographic areas: administrative on the summit, residential on lower terraces, and agricultural on the lowest land. Using geospatial analysis, I modeled the relationship between the site's public and private buildings, its 15 reservoirs, and its hydrology. Water was collected and stored within each of the three topographic zones for local use; however, administrative neighborhoods were located close to reservoirs in order to maintain tight control. Excavations at the site's summit revealed that the central reservoir was in use since the late Preclassic (400 BC-250 AD). They also revealed a complex drainage system that diverted water into an aqueduct that emptied into a canal feeding this reservoir. Overflow from the reservoir was directed to reservoirs further downhill. Drainage flowed from the administrative center to the cardinal directions in accordance with Maya cosmological principles. The link between water and authority is further illustrated by the discovery, in an administrative neighborhood, of a stela depicting a royal ancestor in the act of impersonating Chak, the Maya rain god. At Xultun, the association of administrative neighborhoods with reservoirs in all three topographic areas reflects centralized control and management of urban water resources. The arrangement of hydrological systems emphasized cosmological principles and reinforced authority through ritual association with the rain deity. Water management was instrumental in the maintenance of power. As a key element of statecraft, its stratified spatial organization supported the hierarchical social order that took root in the Preclassic and came to characterize Maya urbanism.

Rapid biodiversity change at a global scale requires enhanced monitoring tools to predict how shifting environmental conditions might alter species’ extinction risk. Emerging remote sensing tools are essential to these efforts and provide the sole mechanism to detect environmental changes and their potential consequences for biodiversity rapidly. Here, I assess the extent to which remote sensing measurements predict species richness globally and within regions, facilitating the establishment of a single framework for monitoring diversity worldwide. I assembled global remote sensing metrics and data on diversity gradients to construct and cross-validate models predicting species richness of birds and mammals within and among the world’s biogeographic zones. Enhanced vegetation Index (EVI), land surface temperature (LST), the first principal component of habitat heterogeneity, and an interaction between energy and habitat heterogeneity are important remotely-sensed environmental measurements for predicting trends of species richness of birds and mammals at all scales, although the intensity of the relationship differs between groups and grain sizes. However, a global model does not explain differences in species richness of birds between distinct zoogeographical realms, indicating a possible threshold in biodiversity change prediction before onset of novel environmental conditions. Measuring potential nonlinear changes in species richness is a useful application of the essential biodiversity variables (EBV) framework for operational monitoring of global and regional biodiversity. The continued production of reliable and consistent remote sensing will facilitate further exploration of current and upcoming drivers of biodiversity change and will help improve macroecological models.

This project investigates applications of GIS and remote sensing to advance the hydrological understanding and improve the management of the water resources in large semi-arid regions. In the Lake Chad Basin, Africa, it is demonstrated how remotely sensed data can contribute significantly to a groundwater problem, something which historically has not often been achieved, particularly in semi-arid areas. In semi-arid areas, water is scarce and groundwater is often the only perennial resource available for the population. In the central part of Lake Chad Basin, this study focuses on the Quaternary aquifer which covers a vast surface area of 500,000 km 2 and provide most of the water used by human activities (Eberschweiler, 1993; FAO-Schroeter and Gear, 1973; UNESCO-PNUD-CBLT, 1972). So far, there are significant differences in the estimations of recharge and discharge phenomena of the Quaternary aquifer. Another scientific issue is the presence across the Quaternary aquifer of large piezometric depressions (Eberschweiler, 1992; FAO-Schroeter and Gear, 1973; Greigert, 1979; Schneider, 1969; Schneider and Wolff, 1992; UNESCO-PNUD-CBLT, 1972). Although, various theories about their formation and their mechanism have be raised (Aranyossy and Ndiaye, 1993; Dieng and Ledoux, 1987; Dieng et al., 1990; Durand, 1995), up to now little or no evidence has been gathered to confirm a particular explanation. An analysis of the basin's data shows that the use of GIS and appropriate remotely sensed data can greatly enhance the information currently available to hydrologists and hydrogeologists. The use of GIS and remote sensing to map groundwater recharge and discharge areas constitutes, in this kind of environment, a novel application. In the centre of the Lake Chad Basin, this approach has highlighted our knowledge of recharge and discharge processes, and it has enabled mapping major recharge and discharge areas. Among the outcomes, this approach has compiled, for the first time, evidence that the piezometric depressions correspond to very low infiltration areas. The fact that the rainfall recharge is considerably limited leads us to believe that evapotranspiration processes dominate the vertical exchanges, and that the piezometric depressions correspond to discharge areas. In the dunefields, a multitude of small discharge areas are revealed by vegetation indices, which show that the vegetation remains very active during the dry season. Such areas correspond to active oases, and were mapped in the Manga and at the border of the Harr and Kanem regions. Surprisingly, there are neither active oases, nor any tree layers, over the piezometric domes. One can deduce that the transpiration processes are lower than in the rest of the dunefield, and thus that the net recharge of the aquifer might be higher. Overall, throughout the Quaternary aquifer, surface characteristics (topography, soil permeability and vegetation) appear to have a strong influence on recharge and discharge processes. A groundwater model of the whole of the Quaternary aquifer was developed to explore novel applications of GIS and remote sensing in groundwater modelling. The model has allowed new knowledge of the aquifer system to be gained and has offered a first quantification of the groundwater reserves. The model's calibration in steady-state was first conducted independently of applications of CIS and remote sensing to map groundwater recharge and discharge areas. Outcomes clearly back up the information revealed with GIS and remote sensing. It was then possible to use remote sensing and GIS to improve the calibration of the model with a finer definition of recharge and discharge areas. The steady-state model has given information on the value and the distribution of long-term regional recharge and discharge. Rainfall recharge takes place in the dunefields, but appears to be small (less than 1 mm/yr in the Manga and less than 5 mm/yr in the centre of the Harr and Kanem). The model shows the necessity of representing the piezometric depressions as discharge areas. A good representation is obtained for a discharge rate below 3 mm/yr. The contribution from Lake Chad is very different from previous estimations and is thought to be less than 100E+06 mVyr (Carmouze, 1983; Isiorho, 1996; Roche, 1980). The model was then extended to a transient simulation from 1960 to 2000. Satellite archived data and GIS have allowed a comprehensive reconstruction of the fluctuations of the extent of Lake Chad. These data were implemented into the groundwater model in order to assess the impact of this major environmental change on the aquifer. This novel application, which makes an intensive use of remote sensing and GIS in the model, demonstrates the value of archive satellite data for long-term groundwater modelling. The model shows that the impact of the shrinkage of Lake Chad on the aquifer is limited in space to the Lake's region. It also reveals that the aquifer's reserves are threatened by the increase of the population in densely populated areas (Maiduguri, N'Djamena and "zone de concentration"). The drop of the water table in the dunefields could be related to a decrease of the rainfall recharge by more than 50%. Overall, the water budget of the aquifer is characterised by the endorheism of the system, with most of the outflows assured internally. Also, with regard to water resources management, the Quaternary aquifer offers a paradox: it is characterised by vast reserves, but a small renewable resource (recharge). It is, to the best of our knowledge, the first time that a large superficial aquifer of the Sahel has been modelled so thoroughly and understood as a whole. This study clearly illustrates the value of GIS and remotely sensed data in the hydrogeology of semi-arid areas. Successful applications of the Lake Chad Basin leads us to believe that in other semi-arid regions of the world, remote sensing and GIS could bring valuable assistance to hydrologists and hydrogeologists.

Five penguin species breed in Antarctica: emperors, Adélies, chinstraps, gentoos and macaronis. These are important Antarctic mid-trophic level predators and under predicted climate change are believed threatened. Accurate monitoring of populations is therefore of growing importance owing to the changing environment in which they live, particularly on the Western Antarctic Peninsula where rapid warming is occurring. The inaccessibility and size of many colonies makes ground based monitoring difficult with remote sensing providing an alternative, relatively low cost, monitoring method. Advancing current monitoring methods will help improve estimates of population trajectories at a regional scale. Recent and future progress in remote sensing, with new satellite sensors and platforms, offers increased potential for accurate, consistent large-scale data collection. The work in this thesis focuses on difficult to monitor brush-tailed penguins (Adélies, chinstraps and gentoos), aiming to develop new techniques and algorithms to improve their monitoring by satellite imagery. Penguin detection in satellite imagery is based on the red/brown guano stains that colonies create, with these stains evident from space. Fieldwork undertaken in Antarctica (Nov 2014-Jan 2015) using a field spectroradiometer obtained the first in situ hyperspectral reflectance spectra of Adélie and chinstrap guano. These spectra are used to identify the features responsible for varying guano types and suggest new indices for differentiating these in satellite imagery. Satellite imagery coincident with the fieldwork, obtained from WorldView-3 (~40 cm resolution) and Landsat 8 (~15 m resolution), are used to trial the index derived from the field spectra. Analysis of the field data and satellite images includes examination of guano colour for different species and comparison of methods of guano detection, aiming to enhance species detection from satellite imagery. In addition, Landsat 8 imagery from further locations is used to produce time series of this index for colonies, examining how guano colour changes over the breeding season are seen in satellite imagery. This dissertation concludes with recommendations for future developments of satellite-based methods based on the results of these analyses. Such improvements should help improve our current understanding of penguin population and continuing population changes in relation to climate change.

The majority of the impact of climate and human induced changes on forest are related to climate variability and deforestation. Similarly, changes in forest phenology due to climate variability and deforestation has been recognized as being among the most important early indicators of the impact of environmental change on forest ecosystem functioning. Comprehensive data on baseline forest cover changes including deforestation is required to provide background information needed for governments to make decision on Reducing Emissions from Deforestation and Forest Degradation (REED). Despite the fact that Nigeria ranks among the countries with highest deforestation rates based on Food and Agricultural Organization estimates, only a few studies have aimed at mapping forest cover changes at country scales. However, recent attempts to map baseline forest cover and deforestation in Nigeria has been based on global scale remote sensing techniques which do not confirm with ground based observations at country level. The aim of this study is two-fold: firstly, baseline forest cover was estimated using an ‘adaptive’ remote sensing model that classified forest cover with high accuracies at country level for the savanna and rainforest zones. The first part of this study also compared the potentials of different MODIS data in detecting forest cover changes at regional (cluster level) scale. The second part of this study explores the trends and response of forest phenology to rainfall across four forest clusters from 2002 to 2012 using vegetation index data from the MODIS and rainfall data obtained from the TRMM.

This thesis deals with the problem of light pollution. In the theoretical part it brings description of the types of light pollution, effects on organisms, information about remote sensing and characteristics of satellites which are used to map light pollution. Time composition images from DMSP satellites (F10-F18) are processed in the practical part. Changes in light intensity for the period 1992 to 2013 are described using these images. During visual assessment the most noticeable changes were obvious when comparing 1992 and 2013, when significant growth of light pollution was especially visible around cities. Statistical evaluation showed increasing values in the categories which contain higher DN (digital number) value. This increase also represents a shift to a higher light intensity level. The results suggest that light pollution in the Czech Republic tends to grow.

Os cereais destinados a produção de grãos (trigo) e de pastagens (azevém) são alvos espectralmente semelhantes, o que dificulta a sua identificação e discriminação em imagens de satélite ao usar sensoriamento remoto. Entretanto, o ciclo fenológico destas culturas é diferente. A análise do perfil multitemporal dos talhões torna-se a estratégia mais adequada para a discriminação destes alvos, os quais apresentam ciclos fenológicos diferentes, porém são espectralmente semelhantes. Usaram-se as imagens bissemanais (vermelho, infravermelho próximo e infravermelho médio) do produto MOD13q1 do sensor MODIS para aplicar um modelo linear de mistura espectral, do qual foram geradas as imagens fração: vegetação, solo e sombra (água). Utilizou-se a distância de Bhattacharyya para realizar uma análise prévia de separabilidade das classes de trigo e azevém geradas. As composições NDVI do produto MOD13q1 foram utilizadas para a segmentação de imagens e para a geração dos perfis multitemporais, os quais foram elaborados usando pontos de controle (lavouras) coletados em saída de campo com auxílio de GPS. Usaram-se as imagens NDVI 129, 177 e 257 do ano de 2009 na segmentação. O mapeamento foi realizado usando o Isodata implementado no Spring 5.0.3, e várias classificações foram testadas. Os dados do mapeamento final foram comparados com dados do IBGE. A estimativa oficial do IBGE para as pastagens é de 118.657 ha para os 42 municípios da área de estudo (metade sul do RS), uma diferença de 18.018 ha a mais quando comparada com a estimativa do mapeamento, de 100.639 ha. Dos 42 municípios que compõem a área de estudo, 19 apresentaram uma diferença menor do que 1.000 ha ao compararem-se os dados do IBGE com o mapeamento. A estimativa dos cereais destinados a produção de grãos foi de 73.690 ha de acordo com o IBGE, uma diferença de 9.543 ha a menos quando comparada com a estimativa do mapeamento, de 83.233 ha. Dos 42 municípios que compõem a área de estudo, 25 apresentaram uma diferença menor do que 1.000 ha. / When employing remote sensing, the cereals destined for grain production (wheat) and pasture (ryegrass) become spectrally similar targets, which makes their identification and distinction more difficult on satellite images. Nevertheless, the phenological cycle of both cultures is different. Thus, the analysis of the multi-temporal profile of plots results in the most suitable strategy for the distinction of those targets, which have unalike phenological cycles but are spectrally similar. Biweekly images (red, near-infrared and mid-infrared) of the product MOD13q1 from MODIS sensor were employed in order to apply a linear model of spectral mixture, from which fraction images were rendered: vegetation, soil and shade (water). The Bhattacharyya distance was used to perform a previous analysis of the separability of generated wheat and ryegrass classes. The NDVI composites of the product MOD13q1 were used in image segmentation and in the multi-temporal profiles rendering, which were elaborated by exploiting control points (crops) gathered in trip field with the aid of GPS. Images NDVI 129, 177 and 257 from the year 2009 were used in the segmentation. The mapping was carried out by employing the Isodata implemented in Spring 5.0.3, and several classifications were tested. The final mapping’s data were compared with IBGE’s data. According to IBGE’s official estimate, there are 118.657 ha of pastures in the 42 cities of the study area (south half of RS), a difference of 18.018 ha more in comparison to the mapping’s estimate, which is of 100.639 ha. Out of the 42 cities that totalize the study area, 19 presented a difference of less than 1.000 ha when comparing IBGE’s data to the mapping’s data. As stated by IBGE, the estimate of cereals destined for grain production was of 73.690 ha (a difference of 9.543 ha less in comparison to the mapping’s estimate of 83.233 ha. Out of the 42 cities that totalize the study area, 25 showed a difference of less than 1.000 ha.

A quantificação da precipitação é dificultada pela extrema aleatoriedade do fenômeno na natureza. Os métodos convencionais para mensuração da precipitação atuam no sentido de espacializar a precipitação mensurada pontualmente em postos pluviométricos para toda a área de interesse e, desta forma, uma rede com elevado número de postos bem distribuídos em toda a área de interesse é necessária para um resultado satisfatório. No entanto, é notória a escassez de postos pluviométricos e a má distribuição espacial dos poucos existentes, não somente no Brasil, mas em vastas áreas do globo. Neste contexto, as estimativas da precipitação com técnicas de sensoriamento remoto e geoprocessamento pretendem potencializar a utilização dos postos pluviométricos existentes através de uma espacialização baseada em critérios físicos. Além disto, o sensoriamento remoto é a ferramenta mais capaz para gerar estimativas de precipitação nos oceanos e nas vastas áreas continentais desprovidas de qualquer tipo de informação pluviométrica. Neste trabalho investigou-se o emprego de técnicas de sensoriamento remoto e geoprocessamento para estimativas de precipitação no sul do Brasil. Três algoritmos computadorizados foram testados, sendo utilizadas as imagens dos canais 1, 3 e 4 (visível, vapor d’água e infravermelho) do satélite GOES 8 (Geostacionary Operational Environmental Satellite – 8) fornecidas pelo Centro de Previsão de Tempo e Estudos Climáticos do Instituto Nacional de Pesquisas Espaciais. A área de estudo compreendeu todo o estado do Rio Grande do Sul, onde se utilizaram os dados pluviométricos diários derivados de 142 postos no ano de 1998. Os algoritmos citados buscam identificar as nuvens precipitáveis para construir modelos estatísticos que correlacionem as precipitações diária e decendial observadas em solo com determinadas características físicas das nuvens acumuladas durante o mesmo período de tempo e na mesma posição geográfica de cada pluviômetro considerado. Os critérios de decisão que norteiam os algoritmos foram baseados na temperatura do topo das nuvens (através do infravermelho termal), reflectância no canal visível, características de vizinhança e no plano de temperatura x gradiente de temperatura Os resultados obtidos pelos modelos estatísticos são expressos na forma de mapas de precipitação por intervalo de tempo que podem ser comparados com mapas de precipitação obtidas por meios convencionais. / The quantification of precipitation is made difficult due mainly to the extreme variance of the phenomenom in nature. The usual methods work in the sense of spacializing the precipitation, which is measured punctually in pluviometric stations, for the entire area of interest and, hence, a net containing a big amount of stations well distributed along the whole area of interest is needed to reach a satisfactory result. Nevertheless, the scarcity of pluviometric stations and the bad distribution of the few existents is evident, not only in Brazil, but also in vast regions of the planet. In this context, the precipitation estimations using remote sensing techniques and geoprocessing intend to potencialize the utilization of existent pluviomteric stations through a spacialization based on physics criteria. Moreover, the remote sensing is the more capable tool to generate rainfall estimation for the oceans and the large continental areas that are unprovided of any type of pluviometric informations. At this work, the application of remote sensing and geoprocessing techniques for precipitation estimation at the south of Brazil was investigated. Three computerized algorithms were tested, based on the imagens of channels 1, 3 and 4 (visible, water steam and infrared) of the GOES 8 satellite, provided by Centro de Previsão de Tempo e Estudos Climáticos of the Instituto Nacional de Pesquisas Espaciais. The studyng area is the Rio Grande do Sul state, where the 1998’s daily precipitation data of 142 raingauges were used. The related algorithms try to identify precipitables clouds to build a mathematical model (through the minimum square process) which correlates the daily precipitation observed in ground with fisical features of the clouds acumulated during the same period and in the same geographic position of the raingauge. These algorithms tested decision criteria based on the temperature of the cloud tops (through thermal infrared), albedo in the visible channel, texture in the infrared channel and in the plane temperature versus temperature gradient. The results obtained by mathematical models are expressed as daily precipitation maps which can be compared with isohyetal maps obtained by conventional methods.

Os objetivos deste trabalho são: determinar o geóide do Estado de São Paulo (SP) pela técnica matemática Fast Collocation utilizando o modelo do geopotencial CG01c, derivado das novas missões gravimétricas de satélite CHAMP e GRACE, avaliar esse geóide através de estações com alturas geoidais conhecidas e do geóide calculado por Souza (2002), e apresentar uma nova abordagem que amplia a idéia sobre o sensoriamento remoto. O modelo do geopotencial CG01c, obtido com dados das missões CHAMP, GRACE e dados de superfície, e desenvolvido até o grau e ordem 360, foi utilizado para geração de anomalias gravimétricas, as quais foram subtraídas das anomalias gravimétricas terrestres, gerando as anomalias gravimétricas residuais. Essas anomalias residuais serviram de dados de entrada no programa FASTCOL para gerar as alturas geoidais residuais. A essas alturas geoidais residuais foi adicionado o modelo CG01c, representativo dos longos comprimentos de onda do campo de gravidade terrestre, produzindo-se o modelo geoidal chamado GEÓIDESP_FC_2007. Este geóide foi avaliado e posteriormente comparado com o Modelo Digital do Geóide Regular (MDGR). Ao final, argumentos foram apresentados para justificar o estudo do campo de gravidade da Terra no âmbito do sensoriamento remoto. / The objectives of this work are: to determine the geoid of the São Paulo (SP) State applying the mathematical technique so-called Fast Collocation using the CG01c geopotential model, from the new satellite gravity missions CHAMP and GRACE, to evaluate that geoid by stations with known geoidal heights and by the geoid determined by Souza (2002), and to show a new approach that enlarges the idea about the remote sensing. The CG01c geopotential model, obtained from missions CHAMP, GRACE and surface data, and developed up to degree and order 360, it was used to obtain the gravity anomalies, which were subtracted of the terrestrial gravity anomalies, yielding the residuals gravity anomalies. These residuals gravity anomalies it was input to the FASTCOL software to yield the residuals geoidal heights. The CG01c geopotential model, representative of the long wavelengths of the earth gravity field, was added to the residuals geoidal heights, yielding the geoid model so-called GEÓIDESP_FC_2007. This geoid was evaluated and later compared with the Modelo Digital do Geóide Regular (MDGR). At the end, arguments were presented to justify the study of the earth gravity field in the scope of the remote sensing