El fenómeno El Niño provoca intensas precipitaciones pluviales que se acumulan y discurren por la superficie, transportando importantes caudales de agua que se incrementan con el desplazamiento debido a la carencia de un pavimento permeable como sucede en la ciudad de Tumbes. Esta deficiencia produce daños en los sistemas de abastecimiento de agua, alcantarillado y aguas pluviales que, debido a la cantidad de basura y lodo que transportan los azolvamientos severos, afectan a las infraestructuras hidráulicas, medio ambiente y calidad de vida de la población. Una propuesta de solución es utilizar un sistema de drenaje urbano sostenible que permita complementar el sistema único de saneamiento diseñado para las aguas servidas, residuales y pluviales, existente en la gran mayoría de ciudades. Esta solución consiste en el diseño de un pavimento permeable porque permite alcanzar un volumen de captación de agua de 81-730 l/min/m2 debido al contenido de vacíos de 13 a 25%. Esta característica física es importante para garantizar la infiltración de grandes volúmenes de agua mediante sus poros para luego transmitir a estratos subyacentes; reducir el flujo del calor al conductor; y mitigar la isla de calor urbano en las ciudades. La presente investigación tiene como objetivo evaluar el desempeño del concreto permeable mediante 5 diseños de mezcla para estudiar la resistencia a la compresión, a la flexión y permeabilidad; la comparación de la escorrentía superficial pluvial de un pavimento de concreto permeable con un pavimento de concreto convencional mediante el software SWMM 5.1; y la comparación respecto al costo. / The El Niño phenomenon causes intense rainfall that accumulates and runs over the surface, transporting significant volumes of water that increase with displacement due to the lack of a permeable pavement, as happens in the city of Tumbes. This deficiency causes damage to the water supply, sewerage, and rainwater systems that, due to the amount of garbage and mud transported by severe silts, affect the hydraulic infrastructures, environment, and quality of life of the population. A proposed solution is to use a sustainable urban drainage system that allows complementing the unique sanitation system designed for sewage, waste, and storm water, existing in most cities. This solution consists of the design of a permeable pavement because it allows reaching a water collection volume of 81-730 l/min/m2 due to the void content of 13 to 25%. This physical characteristic is important to guarantee the infiltration of large volumes of water through its pores and then transmit to underlying strata; reduce heat flow to the conductor; and mitigate the urban heat island in cities. The objective of this research is to evaluate the performance of permeable concrete through 5 mix designs to study the resistance to compression, bending and permeability; the comparison of the surface rain runoff of a permeable concrete pavement with a conventional concrete pavement using SWMM 5.1 software; and the cost comparison. / Tesis

Central America is a region regularly affected by natural disasters, with most of them having a hydro-meteorological origin. Therefore, the understanding of annual changes of precipitation upon the region is relevant for planning and mitigation of natural disasters. This thesis focuses on studying the precipitation variability at annual scales in Central America within the framework of the Swedish Centre for Natural Disaster Science. The aims of this thesis are: i) to establish the main climate variability sources during the boreal winter, spring and summer by using different statistical techniques, and ii) to study the connection of sea surface temperature anomalies of the neighbouring oceans with extreme precipitation events in the region. Composites analysis is used to establish the variability sources during winter. Canonical correlation analysis is employed to explore the connection between the SST anomalies and extreme rainfall events during May-June and August-October. In addition, a global circulation model is used to replicate the results found with canonical correlation analysis, but also to study the relationship between the Caribbean Sea surface temperature and the Caribbean low-level jet. The results show that during winter both El Niño Southern Oscillation and the Pacific Decadal Oscillation, are associated with changes of the sea level pressure near the North Atlantic Subtropical High and the Aleutian low. In addition, the El Niño Southern Oscillation signal is intensified (destroyed) when El Niño and the Pacific Decadal Oscillation have the same (opposite) sign. Sea surface temperature anomalies have been related to changes in both the amount and temporal distribution of rainfall. Precipitation anomalies during May-June are associated with sea surface temperature anomalies over the Tropical North Atlantic region. Whereas, precipitation anomalies during August-September-October are associated with the sea surface temperature anomalies contrast between the Pacific Ocean and the Tropical North Atlantic region. Model outputs show no association between sea surface temperature gradients and the Caribbean low-level jet intensification. Canonical correlation analysis shows potential for prediction of extreme precipitation events, however, forecast validation shows that socio-economic variables must be included for more comprehensive natural disaster assessments.

Corn production in the United States has become increasingly efficient over the years. The use of nitrogen fertilizers has played a substantial role in this efficiency. Nitrogen drives biomass production which leads to increased yields. Unlike other nutrients, nitrogen is more mobile making it easier to lose through leaching and volatilization. The first part of this analysis uses an econometric model to examine the relationship between nitrogen usage and weather data. This relationship leads to farm management decisions to reduce nitrogen fertilization expenses. In addition to the use of nitrogen fertilizers, farmers in Kentucky take advantage of an abundance of poultry litter as a fertilizer source. Traditional poultry litter fertilization methods are being challenged by new technology, sub-surface injection, which has the potential to increase corn yields as compared to other methods. The second part of this analysis uses a resource allocation linear programming model to determine the economic viability of the sub-surface injection method for both spring and fall fertilizer applications. This model also reveals both farm management implications and provides valuable information for the development and commercialization of the sub-surface injector.

Der rezente und zukünftige Anstieg der atmosphärischen Treibhausgaskonzentration bedeutet für das terrestrische Klimasystem einen grundlegenden Wandel, der für die globale Gesellschaft schwer zu bewältigende Aufgaben und Herausforderungen bereit hält. Eine effektive, rühzeitige Anpassung an diesen Klimawandel profitiert dabei enorm von möglichst genauen Abschätzungen künftiger Klimaänderungen. Das geeignete Werkzeug hierfür sind Gekoppelte Atmosphäre Ozean Modelle (AOGCMs). Für solche Fragestellungen müssen allerdings weitreichende Annahmen über die zukünftigen klimarelevanten Randbedingungen getroffen werden. Individuelle Fehler dieser Klimamodelle, die aus der nicht perfekten Abbildung der realen Verhältnisse und Prozesse resultieren, erhöhen die Unsicherheit langfristiger Klimaprojektionen. So unterscheiden sich die Aussagen verschiedener AOGCMs im Hinblick auf den zukünftigen Klimawandel insbesondere bei regionaler Betrachtung, deutlich. Als Absicherung gegen Modellfehler werden üblicherweise die Ergebnisse mehrerer AOGCMs, eines Ensembles an Modellen, kombiniert. Um die Abschätzung des Klimawandels zu präzisieren, wird in der vorliegenden Arbeit der Versuch unternommen, eine Bewertung der Modellperformance der 24 AOGCMs, die an der dritten Phase des Vergleichsprojekts für gekoppelte Modelle (CMIP3) teilgenommen haben, zu erstellen. Auf dieser Basis wird dann eine nummerische Gewichtung für die Kombination des Ensembles erstellt. Zunächst werden die von den AOGCMs simulierten Klimatologien für einige grundlegende Klimaelemente mit den betreffenden klimatologien verschiedener Beobachtungsdatensätze quantitativ abgeglichen. Ein wichtiger methodischer Aspekt hierbei ist, dass auch die Unsicherheit der Beobachtungen, konkret Unterschiede zwischen verschiedenen Datensätzen, berücksichtigt werden. So zeigt sich, dass die Aussagen, die aus solchen Ansätzen resultieren, von zu vielen Unsicherheiten in den Referenzdaten beeinträchtigt werden, um generelle Aussagen zur Qualität von AOGCMs zu treffen. Die Nutzung der Köppen-Geiger Klassifikation offenbart jedoch, dass die prinzipielle Verteilung der bekannten Klimatypen im kompletten CMIP3 in vergleichbar guter Qualität reproduziert wird. Als Bewertungskriterium wird daher hier die Fähigkeit der AOGCMs die großskalige natürliche Klimavariabilität, konkret die hochkomplexe gekoppelte El Niño-Southern Oscillation (ENSO), realistisch abzubilden herangezogen. Es kann anhand verschiedener Aspekte des ENSO-Phänomens gezeigt werden, dass nicht alle AOGCMs hierzu mit gleicher Realitätsnähe in der Lage sind. Dies steht im Gegensatz zu den dominierenden Klimamoden der Außertropen, die modellübergreifend überzeugend repräsentiert werden. Die wichtigsten Moden werden, in globaler Betrachtung, in verschiedenen Beobachtungsdaten über einen neuen Ansatz identifiziert. So können für einige bekannte Zirkulationsmuster neue Indexdefinitionen gewonnen werden, die sich sowohl als äquivalent zu den Standardverfahren erweisen und im Vergleich zu diesen zudem eine deutliche Reduzierung des Rechenaufwandes bedeuten. Andere bekannte Moden werden dagegen als weniger bedeutsame, regionale Zirkulationsmuster eingestuft. Die hier vorgestellte Methode zur Beurteilung der Simulation von ENSO ist in guter Übereinstimmung mit anderen Ansätzen, ebenso die daraus folgende Bewertung der gesamten Performance der AOGCMs. Das Spektrum des Southern Oscillation-Index (SOI) stellt somit eine aussagekräftige Kenngröße der Modellqualität dar. Die Unterschiede in der Fähigkeit, das ENSO-System abzubilden, erweisen sich als signifikante Unsicherheitsquelle im Hinblick auf die zukünftige Entwicklung einiger fundamentaler und bedeutsamer Klimagrößen, konkret der globalen Mitteltemperatur, des SOIs selbst, sowie des indischen Monsuns. Ebenso zeigen sich signifikante Unterschiede für regionale Klimaänderungen zwischen zwei Teilensembles des CMIP3, die auf Grundlage der entwickelten Bewertungsfunktion eingeteilt werden. Jedoch sind diese Effekte im Allgemeinen nicht mit den Auswirkungen der anthropogenen Klimaänderungssignale im Multi-Modell Ensemble vergleichbar, die für die meisten Klimagrößen in einem robusten multivariaten Ansatz detektiert und quantifiziert werden können. Entsprechend sind die effektiven Klimaänderungen, die sich bei der Kombination aller Simulationen als grundlegende Aussage des CMIP3 unter den speziellen Randbedingungen ergeben nahezu unabhängig davon, ob alle Läufe mit dem gleichen Einfluss berücksichtigt werden, oder ob die erstellte nummerische Gewichtung verwendet wird. Als eine wesentliche Begründung hierfür kann die Spannbreite der Entwicklung des ENSO-Systems identifiziert werden. Dies bedeutet größere Schwankungen in den Ergebnissen der Modelle mit funktionierendem ENSO, was den Stellenwert der natürlichen Variabilität als Unsicherheitsquelle in Fragen des Klimawandels unterstreicht. Sowohl bei Betrachtung der Teilensembles als auch der Gewichtung wirken sich dadurch gegenläufige Trends im SOI ausgleichend auf die Entwicklung anderer Klimagrößen aus, was insbesondere bei letzterem Vorgehen signifikante mittlere Effekte des Ansatzes, verglichen mit der Verwendung des üblichen arithmetischen Multi-Modell Mittelwert, verhindert. / The recent and future increase in atmospheric greenhouse gases will cause fundamental change in the terrestrial climate system, which will lead to enormous tasks and challenges for the global society. Effective and early adaptation to this climate change will benefit hugley from optimal possible estimates of future climate change. Coupled atmosphere-ocean models (AOGCMs) are the appropriate tool for this. However, to tackle these questions, it is necessary to make far reaching assumptions about the future climate-relevant boundary conditions. Furthermore there are individual errors in each climate model. These originate from flaws in reproducing the real climate system and result in a further increase of uncertainty with regards to long-range climate projections. Hence, concering future climate change, there are pronounced differences between the results of different AOGCMs, especially under a regional point of view. It is the usual approach to use a number of AOGCMs and combine their results as a safety measure against the influence of such model errors. In this thesis, an attempt is made to develop a valuation scheme and based on that a weighting scheme, for AOGCMs in order to narrow the range of climate change projections. The 24 models that were included in the third phase of the coupled model intercomparsion project (CMIP3) are used for this purpose. First some fundamental climatologies simulated by the AOGCMs are quantitatively compared to a number of observational data. An important methodological aspect of this approach is to explicitly address the uncertainty associated with the observational data. It is revealed that statements concerning the quality of climate models based on such hindcastig approaches might be flawed due to uncertainties about observational data. However, the application of the Köppen-Geiger classification reveales that all considered AOGCMs are capable of reproducing the fundamental distribution of observed types of climate. Thus, to evaluate the models, their ability to reproduce large-scale climate variability is chosen as the criterion. The focus is on one highly complex feature, the coupled El Niño-Southern Oscillation. Addressing several aspects of this climate mode, it is demonstrated that there are AOGCMs that are less successful in doing so than others. In contrast, all models reproduce the most dominant extratropical climate modes in a satisfying manner. The decision which modes are the most important is made using a distinct approach considering several global sets of observational data. This way, it is possible to add new definitions for the time series of some well-known climate patterns, which proof to be equivalent to the standard definitions. Along with this, other popular modes are identified as less important regional patterns. The presented approach to assess the simulation of ENSO is in good agreement with other approaches, as well as the resulting rating of the overall model performance. The spectrum of the timeseries of the Southern Oscillation Index (SOI) can thus be regarded as a sound parameter of the quality of AOGCMs. Differences in the ability to simulate a realistic ENSO-system prove to be a significant source of uncertainty with respect to the future development of some fundamental and important climate parameters, namely the global near-surface air mean temperature, the SOI itself and the Indian monsoon. In addition, there are significant differences in the patterns of regional climate change as simulated by two ensembles, which are constituted according to the evaluation function previously developed. However, these effects are overall not comparable to the multi-model ensembles’ anthropogenic induced climate change signals which can be detected and quantified using a robust multi-variate approach. If all individual simulations following a specific emission scenario are combined, the resulting climate change signals can be thought of as the fundamental message of CMIP3. It appears to be quite a stable one, more or less unaffected by the use of the derived weighting scheme instead of the common approach to use equal weights for all simulations. It is reasoned that this originates mainly from the range of trends in the SOI. Apparently, the group of models that seems to have a realistic ENSO-system also shows greater variations in terms of effective climate change. This underlines the importance of natural climate variability as a major source of uncertainty concerning climate change. For the SOI there are negative Trends in the multi-model ensemble as well as positive ones. Overall, these trends tend to stabilize the development of other climate parameters when various AOGCMs are combined, whether the two distinguished parts of CMIP3 are analyzed or the weighting scheme is applied. Especially in case of the latter method, this prevents significant effects on the mean change compared to the arithmetic multi-model mean.

Le système d'upwelling péruvien est l'un des systèmes marins côtiers les plus productifs de l’océan mondial. Le vent de surface le long de la côte est le principal moteur de l'upwelling. Cette thèse vise à étudier la variabilité du vent côtier et ses processus lors du réchauffement de la couche de surface, à différentes échelles de temps: (1) des échelles de temps interannuelles, correspondant aux événements El Niño, et (2) des échelles de temps multi-décadaires résultant du changement climatique régional. Une série de domaines emboités d’un modèle atmosphérique régional est utilisée pour simuler le vent de surface. Dans la première partie de la thèse, on étudie les processus responsables de l'augmentation, contre-intuitive, du vent observée au large du Pérou au cours de la période El Niño 1997-1998. Des expériences de sensibilité montrent que le réchauffement inh de la omogène des eaux de surface, plus important dans le nord, entraîne un gradient de pression accru le long côte, accélérant le vent. Dans une seconde partie de la thèse, l’évolution des vents côtiers est étudiée dans le scénario du «pire cas» du changement climatique RCP8.5. Forcés par le gradient de pression le long de la côte, les vents diminuent en été, tandis qu’ils s’accroissent en hiver, renforçant ainsi légèrement le cycle saisonnier. / The Peruvian upwelling system is one of the most productive coastal marine systems of the world ocean. As in other upwelling systems, alongshore surface wind is the main driver of the coastal upwelling. This thesis aims to study the coastal wind variability and the processes responsible for it during the ocean surface layer warming conditions, at different time scales: (1) interannual time scales, corresponding to El Niño events and (2) multi decadal time scales resulting from regional climate change. A suite of regional atmospheric model embedded domains is used to simulate the surface winds. In the first part of the thesis, the counter-intuitive wind increase observed off Peru during the 1997-1998 El Niño is studied. Sensitivity experiments show that the inhomogenous alongshore surface warming, larger in the north, drives an enhanced alongshore pressure gradient that accelerates the alongshore wind. In the second part of the thesis, the evolution of coastal wind changes is investigated under the “worst case” RCP8.5 climate change scenario. Mainly driven by the alongshore pressure gradient, summer winds decrease whereas winter winds increase, thus slightly reinforcing the seasonal cycle.

Le littoral Fluminense, situé en zone tropicale humide (23°S-43°W, Rio de Janeiro, Brésil), présente un gradient d'aridité, généré par l'occurrence d'un upwelling côtier, principalement contrôlé par le régime des vents. Les lagunes du littoral, dont les caractéristiques physico-chimiques sont en relation avec ce gradient d'aridité, enregistrent des variations hydro-climatiques en relation avec l'occurrence de cet upwelling. Ce travail porte sur des enregistrements lagunaires prélevés dans deux lagunes (Brejo do Espinho et Padre) et sur un enregistrement marin prélevé dans la zone de l'upwelling. Les variations hydroclimatiques des lagunes ont été reconstituées à partir de l'étude des diatomées complétée par l'estimation de la salinité quantifiée par une fonction de transfert diatomées/salinité. La fonction de transfert a été établie à partir d'une calibration sur les milieux lagunaires actuels en fonction du gradient de salinité. La variabilité de l'intensité de l'upwelling a été reconstituée à partir de la productivité primaire de la zone d'upwelling basée sur l'étude des coccolithophoridés. La comparaison entre la variabilité hydro-climatique reconstituée dans les lagunes et l'occurrence de l'upwelling, en tenant compte de la remontée du niveau marin au cours de l'Holocène, permet de définir les changements d'intensité de l'upwelling et du régime des vents qui se sont exercés sur le littoral Fluminense. Ces changements peuvent être expliqués par l'impact des événements El Niño, par la position des fronts polaires et la migration de la zone de convergence intertropicale.

Cette thèse analyse (i) la variabilité pluviométrique contemporaine en Nouvelle-Calédonie et ses téléconnexions avec les températures de surface océanique (TSO) du Pacifique tropical et (ii) l'impact des anomalies atmosphériques sur l'activité des incendies estimés par satellites. La Nouvelle-Calédonie figure aujourd'hui parmi les 34 " points chauds " de la biodiversité à l'échelle planétaire. A ce titre, l'un de nos objectifs est de construire un modèle permettant de prévoir l'intensité de la saison des feux entre septembre et décembre, qui correspond au maximum annuel. Le croisement de trois bases de données de feux détectés par satellites (MODIS, ATSR et LANDSAT) avec le réseau des stations météorologiques de Météo-France a montré qu'aucune anomalie thermique significative n'est détectée avant un feu, tandis que de forts déficits pluviométriques par rapport à la normale sont enregistrés jusqu'à trois mois avant le départ des feux. Ces déficits pluviométriques sont partiellement liés aux phases chaudes du phénomène El Niño Southern Oscillation (ENSO) et plus particulièrement à celles durant lesquelles les anomalies thermiques se situent à proximité de la ligne de changement de date équatoriale lors du printemps austral. Ces anomalies renforcent la circulation moyenne de Hadley (via le dégagement de chaleur latente dans la moyenne et haute troposphère) et la subsidence au niveau des latitudes néo-calédoniennes, tandis que les épisodes les plus intenses du siècle dernier (i.e. 1982-83 et 1997-98) dont les anomalies thermiques les plus importantes sont localisées dans le Pacifique oriental, sont associés à des conditions pluviométriques proches de la normale dans le Pacifique sud-ouest (SW). La téléconnexion entre les TSO du Pacifique central et les précipitations du Pacifique SW s'affaiblit à partir du mois de décembre au moment où l'ENSO atteint, paradoxalement, son intensité maximale. Cette modulation saisonnière est le produit d'une interaction entre (i) le cycle saisonnier des TSO brutes dans le Pacifique central, (ii) le cycle de vie des anomalies thermiques des épisodes chauds et (iii) l'intensité du gradient zonal des TSO le long de l'équateur. Par ailleurs, la convection profonde semble particulièrement sensible à la propagation vers l'est des anomalies de TSO faibles-à-modérées au niveau de la ligne de changement de date équatoriale (soit légèrement à l'ouest de la boîte Niño 3.4), modifiant significativement la position et l'intensité de la courroie de transmission des téléconnexions. Une analyse en ondelettes montre que les pluies néo-calédoniennes sont également sensibles à des modes de variations plus lents (> 8 ans) du Pacifique central entre septembre et novembre. La synchronisation entre la saisonnalité des feux et la prévisibilité saisonnière liée à l'ENSO permet d'estimer la surface brûlée totale en septembre-décembre à partir des états thermiques de l'océan Pacifique en juin-août, dont la polarité est clairement établie plusieurs mois à l'avance. La corrélation entre l'observation et la simulation du logarithme du total des surfaces brûlées en Nouvelle-Calédonie est de 0.87 sur la période 2000-2010 selon un modèle linéaire en validation croisée.

The background state and changes associated with the El Niño-Southern Oscillation (ENSO) in the tropical Pacific Ocean influence climate patterns all over the world. Understanding how the tropical Pacific will be impacted by climate change is therefore critical to accurate regional climate projections. However, sparse historical data coverage and strong natural variability in the basin make it difficult to assess the response of the tropical Pacific to anthropogenic climate change. Further, climate models disagree regarding the response of the basin to continued anthropogenic forcing into the future. Building off of the limited instrumental record, high-resolution records from coral and lake sediment archives can be used to assess the response of the tropical Pacific to past climate changes and to compare and assess climate model projections. In the present study, I use high-resolution coral and lake records from the equatorial Pacific to assess climate model projections and the response of the coupled ocean-atmospheric climate system in the basin (ocean temperature, salinity, winds, precipitation) to natural and anthropogenic forcing. Using a simple model of how climate is recorded by corals, we compare historical climate data and climate model simulations with coral paleoclimate records to assess climate model projections and address uncertainties in the historical data, models and paleoclimate records. We demonstrate that this simple model is able to capture variability and trend observed in the coral records, and show that the both sea surface temperature and salinity contribute to the observed coral trend. However, we find major discrepancies in the observed and climate model simulated trends in the tropical Pacific that may be attributed to uncertainties in model simulated salinity. We then assess 20th-century variability and trends in SST and salinity in the central tropical Pacific using replicated coral δ¹⁸O and Sr/Ca records from the Republic of Kiribati and the central Line Islands. We find that the coral records from these sites display a warming and freshening trend superimposed on strong interannual and low-frequency variability. Further, we demonstrate an apparent strengthening of the E-W SST gradient across the dateline (between 173°E and 160°W) and a slight weakening of the N-S SST gradient due to enhanced warming along the equator and west of the dateline relative to other sites. However, we find no evidence of increased variability in the central Pacific, suggesting that there has not been an increase in central Pacific style ENSO events. Finally, we show that the salinity response to climate change may be very patchy within the basin. Using a new ~90 year coral Mn/Ca record from the central Pacific, we investigate variability and trends in tropical Pacific trade winds. First, we demonstrate a strong association between westerly wind anomalies and coral skeletal Mn/Ca, which recorded all of the major historical El Niño events of the 20th century. In this new long Mn/Ca record, we find a reduction in the amplitude and frequency of Mn/Ca pulses between 1893 and 1982, suggesting a decrease in westerly wind anomalies in the western equatorial Pacific Ocean. Finally, we use a sediment record from Bainbridge Crater Lake, Galápagos Archipelago to assess variability in the eastern tropical Pacific over the past ~6 thousand years. Based on results from long-term monitoring of the lake, we propose a new climate interpretation of the sediment record and find further evidence reduced mid-Holocene ENSO variability and a ramp up of ENSO variability starting around 1775 cal. years BP.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-05T17:18:06Z No. of bitstreams: 1 JANDUY GUERRA ARAÚJO - DISSERTAÇÃO PPGMet 2005..pdf: 3419275 bytes, checksum: cfc57ebb78334a2f29ed1f17e87ac1b7 (MD5) / Made available in DSpace on 2018-09-05T17:18:06Z (GMT). No. of bitstreams: 1 JANDUY GUERRA ARAÚJO - DISSERTAÇÃO PPGMet 2005..pdf: 3419275 bytes, checksum: cfc57ebb78334a2f29ed1f17e87ac1b7 (MD5) Previous issue date: 2005-05-30 / Capes / Neste trabalho, a fonte aparente de calor Q1 e o sumidouro aparente de umidade Q2 são investigados para anos de El Niño, de La Niña e anos normais. O objetivo é determinar o nível de máximo Q1 e Q2, as intensidades e a posição de Q1 em relação a Q2. Os dados utilizados são as reanálises do ECMWF e o estudo para cada episódio cobre o período de outubro a março. Inicialmente, são mostradas tabelas com o nível onde ocorre o máximo com base na média para cada mês de cada episódio estudado. As análises são para as regiões Amazônica e Nordeste do Brasil. Depois as intensidades de Q1 e de Q2 em dois níveis de referência são estudadas através de diagramas de Hovmöller ao longo da latitude de 5°S. Os resultados mostram que há uma diferença entre o Nordeste e a Amazônia, no que concerne ao nível de máximo Q1 e Q2 tanto espacial quanto também em relação às intensidades dessas grandezas. Além disso, houve relevantes diferenças entre os anos de El Niño e La Niña em ambas as regiões observadas. Especificamente os anos de La Niña se apresentaram com uma estrutura mais padronizada do nível de ocorrência de Q1 e de –Q2 enquanto que nos anos de El Niño se obteve mais níveis de ocorrência de máxima magnitude dessas entidades, o que evidencia uma estrutura mais desorganizada. Quanto à intensidade, a região tropical do Brasil admite valores de Q1 tão grandes quanto 50K/dia, do ponto de vista de um conjunto de dados com resolução horizontal de 2,5 graus. / In this work, we investigate both the apparent heat source Q1 and the apparent moisture sink Q2 for El Niño, La Niña and normal years. The aim is determining the level of maximum Q1 and Q2 and the intensity and position of Q1 in relation to Q2. Data used are the ECMWF reanalysis and the study spans the period from October through March for each episode. Initially we show tables containing the level where the maximum occurs based on monthly averages for each episode. The analyses are focused on Amazonia and Northeast Brazil. In the sequence, we investigate the intensities of both Q1 and Q2 for two reference levels through Hovmöller diagrams along the 5°S latitude. The results show differences between Northeast Brazil and Amazônia when the level of occurrence of the maximum, the space location and the intensity of both Q1 and Q2 are concerned. Moreover there are substantial event-to-event differences for both regions. La Niña years show a more organized structure in terms of the level of occurrence of Q1 and Q2. On the other hand, El Niño years show a more disorganized structure. Finally, we found that from the viewpoint of a data set with horizontal resolution of 2.5 degree, tropical Brazil admits values of Q1 as large as 50K/day.

Submitted by Nathália Faria da Silva (nathaliafsilva.ufv@gmail.com) on 2017-07-26T14:10:34Z No. of bitstreams: 1 texto completo.pdf: 42061996 bytes, checksum: 1adae48054791a5b3425a70557fcbfe5 (MD5) / Made available in DSpace on 2017-07-26T14:10:34Z (GMT). No. of bitstreams: 1 texto completo.pdf: 42061996 bytes, checksum: 1adae48054791a5b3425a70557fcbfe5 (MD5) Previous issue date: 1997-08-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / No presente trabalho. foram investigadas as influências dos sistemas de escala sinótica na espacialização do fenômeno de veraniço em 18 decêndios da estação chuvosa (outubro a março), para todo o Estado de Minas Gerais. Para tal, foi necessária a utilização de dados de precipitação do DNAEE (Departamento Nacional de Águas e Energia Elétrica). Como objetivo central, obteve-se a espacialização da frequência média do veranico no Estado de Minas Gerais, aplicando um sistema de informações geográficas (SIG), levando-se em conta dados de 90 estações pluviométricas. No estudo de caso de janeiro de 1996, verificou-se a influência do Cavado Compensador Leste sobre o regime de chuvas em Minas Gerais. Os fenômenos de anomalias positivas e negativas (El Nino e La Nina) parecem contribuir para ocorrência de forte estiagem (veranico), podendo afetar todo o Estado. Através dos resultados obtidos, foram desenvolvidas análises do padrão de escoamento atmosférico entre 0°S e 40°S de latitude, aplicando-se o programa GRADS (Grid Analysis and Display Systems), associado ao período de maior frequência média. Por meio desses resultados, o agricultor pode planejar suas atividades agrícolas, evitando ser surpreendido por algum tipo de azar climático, como o veranico. / This study investigated the influences of synoptic scale systems in the spacialization of drought periods in 18 groups often days on the rainy season (October to March) for the State of Minas Gerais. The rainfall data from ninety weather stations, provided by the DNAEE (Departamento Nacional de Águas e Energia Elétrica) were used. The average frequency spacialization of the drought period was obtained for the whole state thnough the application of a geographic information system (GIS). A case study referring to January 1996 evidenced the influence of the East Thoungh on the rainfall regime in Minas Gerais. The positive and negative anomaly phenomena (El Nino and La Nina) presented indications to contribute for occurrence of strong drought. With the obtained results, the analyses of the atmosphere draining patterns between 0º and 40º latitude were developed by applying the GRADS program (Grid Analysis and Display System) associated to the period with the highest average frequency. These results contribute for a better planning of the agricultural activities.