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No description available.

The Lagrangian dynamics of two-dimensional incompressible fluid flows is considered, with emphasis on transport processes in atmospheric and oceanic flows. The dynamical-systems-based approach is adopted; the Lagrangian motion in such systems is studied with the aid of Kolmogorov-Arnold-Moser (KAM) theory, and results relating to stable and unstable manifolds and lobe dynamics. Some nontrivial extensions of well-known results are discussed, and some extensions of the theory are developed. In problems for which the flow field consists of a steady background on which a time-dependent perturbation is superimposed, it is shown that transport barriers arise naturally and play a critical role in transport processes. Theoretical results are applied to the study of transport in measured and simulated oceanographic and atmospheric flows. Two particular problems are considered. First, we study the Lagrangian dynamics of the zonal jet at the perimeter of the Antarctic Stratospheric Polar Vortex during late winter/early spring within which lies the "ozone hole". In this system, a robust transport barrier is found near the core of a zonal jet under typical conditions, which is responsible for trapping of the ozone-depleted air within the ozone hole. The existence of such a barrier is predicted theoretically and tested numerically with use of a dynamically-motivated analytically-prescribed model. The second, oceanographic, application considered is the study of the surface transport in the Adriatic Sea. The surface flow in the Adriatic is characterized by a robust threegyre background circulation pattern. Motivated by this observation, the Lagrangian dynamics of a perturbed three-gyre system is studied, with emphasis on intergyre transport and the role of transport barriers. It is shown that a qualitative change in transport properties, accompanied by a qualitative change in the structure of stable and unstable manifolds occurs in the perturbed three-gyre system when the perturbation strength exceeds a certain threshold. This behavior is predicted theoretically, simulated numerically with use of an analytically prescribed model, and shown to be consistent with a fully observationally-based model.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The present PhD thesis analyzes the results obtained from the Total Ozone Column (TOC) monitoring conducted in the Southern Space Observatory - SSO (29.26 ° S, 53.48 °W and 488 m altitude) between 1992 and 2014 by three successive Brewer spectrophotometers (# 081, # 056 and # 167). First, the Brewer measurements were compared with TOMS (Total Ozone Mapping Spectrometer) and OMI (Ozone Monitoring Instrument) satellites obtaining excellent agreement. In addition, was determined that the seasonal TOC variability is dominated by the annual cycle, with a minimum of ~ 260 DU in April and a maximum of ~ 295 DU in September. The Quasi-Biennial Oscillation (QBO) is the main mode of interannual variability being approximately in antiphase with the QBO index. Next, 58 events of the influence of the Antarctic Ozone Hole on the SSO station was identificate in the period between 2005 and 2014. This events occurred on average 5.8 ± 3.51 times per year, with a mean reduction of TOC by Brewer' of -7.04 ± 2.97% and by OMI of -7.66 ± 3.11 respectively. Analyzing the ozone profiles from AURA/MLS (Microwave Limb Sounder) satellite, the average isentropic level for maximum reduction is 644.68 ± 158.59 K, with a mean reduction of 15.39 ± 6.47%, being October the month of greatest occurrence (18 events). The events were separated into three categories: TOC intensity reduction, height of the ozone reduction lamina in AURA/MLS satellite and the dynamic characteristic of Polar Filament or Polar Tongue through the application of Dybal (Dynamical Barrier Localization) code in the potential vorticity (PV) fields from MIMOSA (Modélisation Isentrope du transport Mésoéchelle de l'Ozone Stratosphérique par Advection) model. The events with a dynamic feature of Polar Tongue (20,68%) occurred more frequently in October, with medium intensity and in the medium stratosphere, while events of dynamic characteristic of Polar Filament (79,31%) occurred more frequently in September, also with medium intensity and in the medium stratosphere. / A presente Tese de Doutorado analisa os resultados obtidos a partir do monitoramento da Coluna Total de Ozônio (CTO) realizado no Observatório Espacial do Sul – OES (29,26 ° S, 53,48 ° e 488 m de altitude) entre 1992 e 2014 através de três sucessivos espectrofotômetros Brewer (# 081, # 056 e # 167). Primeiramente, as medidas dos Brewers foram comparadas com observações dos instrumentos de satélite TOMS (Total Ozone Mapping Spectrometer) e OMI (Ozone Monitoring Instrument), obtendo elevados valores de R2 (0,88 e 0,93, respectivamente). Além disso, foi determinado que a variabilidade sazonal da CTO é dominada pelo ciclo anual, com um mínimo de ~260 DU em abril e um máximo de ~295 DU em setembro. A Oscilação Quasi-Bienal (QBO) é o principal modo de variabilidade interanual estando aproximadamente em antifase com o índice QBO. Em seguida é apresentada a identificação da ocorrência de 58 eventos de Influência do Buraco de Ozônio Antártico sobre a estação do OES no período entre 2005 e 2014, os quais ocorreram em média 5,8 ± 3,5 vezes por ano, com redução média da CTO de Brewer e OMI de -7,04±2,9% e 7,66±3,1 respectivamente. Analisando os perfis de ozônio do satélite AURA/MLS (Microwave Limb Sounder), observa-se que o nível isentrópico médio para a máxima redução é de 644,6±158,5 K com redução média de 15,3±6,4%, sendo outubro o mês de maior ocorrência (18 eventos). Os eventos foram separados em categorias: Intensidade da redução da CTO, altura da camada de redução no perfil do ozônio do satélite AURA/MLS e a característica dinâmica de Filamento Polar ou Língua Polar através da aplicação do código Dybal (Dynamical Barrier Localisation) nos campos de vorticidade potencial (PV) do modelo MIMOSA (Modélisation Isentrope du transport Mésoéchelle de l'Ozone Stratosphérique par Advection). Os eventos com característica dinâmica de Lingua Polar (20,68%) ocorreram com mais frequência no mês de outubro, com intensidade média e na média estratosfera, enquanto que eventos de característica dinâmica de Filamento Polar (79,31%) ocorreram com mais frequência no mês de setembro, também com media intensidade e na média estratosfera.

Le réchauffement régional de l'ouest de la Péninsule Antarctique (WAP) combiné à la diminution attendue de glace de mer et à l'apparition printanière du trou d'ozone pourrait modifier la composition et la structure de la communauté microbienne. De plus, ces variations environnementales pourraient modifier le potentiel de la WAP en tant que puits de CO2. Dans ce contexte, cette thèse visait à évaluer les effets combinés du changement climatique sur la production primaire et sur la composition et la structure de la communauté microbienne de la WAP. Cette thèse visait également à évaluer le rôle de la structure, de la composition, de la production primaire et de la respiration de la communauté microbienne sur les échanges de CO2 entre l'atmosphère et l'océan. Cette étude a premièrement permis de décrire les variations de l'étendue de glace de mer, de l'épaisseur de la couche d'ozone et de la température de surface de l'eau dans la WAP au cours des 30 dernières années (1972-2007) et notamment d'observer le retrait de plus en plus précoce de la glace de mer en relation avec le réchauffement des eaux de la WAP. L'évolution de ces paramètres environnementaux offre une nouvelle fenêtre temporelle de production primaire. Ainsi, cette étude a permis de montrer que la production primaire annuelle a augmenté de 1997 à 2007, et ceci, en relation avec l'anomalie de glace de l'hiver précédent. En effet, la production primaire journalière était négativement et positivement corrélée avec, respectivement, l'étendue de glace de mer et la température de l'eau de septembre à novembre et de février à mars, suggérant que le réchauffement régional de la WAP favorise plus de production primaire durant le printemps et l'automne. En revanche, le retrait précoce de la glace de mer en coïncidence avec l'apparition printanière du trou d'ozone a provoqué l'augmentation de la photoinhibition au printemps (avec 11,6 ± 2,8 % de la production primaire journalière en moyenne). En conséquence, le changement climatique régional de la WAP a, à la fois, un effet positif et un effet négatif sur la production primaire. Cette étude a également permis de décrire la dynamique de la communauté microbienne marine dans l'archipel de Melchior (dans la WAP) de l'automne au printemps 2006. En raison des conditions environnementales extrêmes, l'abondance et la biomasse de la communauté microbienne étaient faibles durant l'automne et l'hiver et dominées par les petites cellules (< 2 µm) et donc par un réseau trophique microbien. En effet, la biomasse phytoplanctonique était faible durant l'automne et l'hiver (avec une concentration moyenne en chlorophylle a, Chl-a, de 0,3 et 0,13 µg l-1, respectivement). La biomasse phytoplanctonique a augmenté au printemps (avec un maximum de Chl-a de 1,13 µg l-1), mais, en dépit des conditions de croissance favorables, est restée faible et le phytoplancton était toujours dominé par de petites cellules (2-20 µm) et donc par le réseau trophique microbien ou multivore. De plus, la disparition précoce de glace de mer durant le printemps 2006 a exposé les eaux de la WAP à de fortes radiations ultraviolettes B (RUVB, 280-320 nm), qui ont eu un effet négatif sur la communauté microbienne des eaux de surface. Cette étude a également mis en évidence la relation existante entre les échanges CO2 et d'O2 entre l'atmosphère et l'océan dans la WAP et la biomasse, la composition, la production primaire et la respiration de la communauté microbienne. Il existait tout d'abord une relation positive entre la concentration en Chl-a et la proportion de diatomées dans la communauté phytoplanctonique. De plus, il existait une corrélation négative significative entre la Chl-a et le ΔpCO2. La production primaire nette de la communauté (NCP) était principalement contrôlée par la production primaire et était négativement et positivement reliée avec le ΔpCO2 et le pourcentage de saturation de l'O2, respectivement, suggérant que la production primaire joue un rôle majeur dans les échanges de CO2 et d'O2 entre l'atmosphère et l'océan dans la WAP. Par ailleurs, le ΔpCO2 moyen au cours des trois années étudiées était de -20,04 ± 44,3 µatm, menant à un puits de CO2 potentiel durant l'été et l'automne dans la région. Le sud de la WAP était un puits potentiel de CO2 (-43,60 ± 39,06 µatm) durant l'automne alors que le nord de la WAP était principalement une source potentielle de CO2 durant l'été ou l'automne (-4,96 ± 37,6 et 21,71 ± 22,39 µatm, respectivement). Les plus fortes concentrations en Chl-a mesurées dans le sud de la WAP pourraient expliquer cette distribution spatiale. / Regional warming in the western Antarctic Peninsula (WAP), along with the expected decrease in sea-ice cover and the seasonal ozone layer breakdown could modify the composition and the structure of the microbial community. In addition, these environmental changes could modify the potential of the WAP as a CO2 sink. In this context, this thesis aimed at evaluating the combined effects of regional climatic changes on the primary production and the composition and structure of the microbial community in the WAP. In a second time, this thesis aimed at evaluating the role of the microbial community structure, composition, primary production and respiration on air-sea CO2 gas exchanges.First, the variations in sea-ice cover, stratospheric ozone layer thickness and sea surface temperature over the last 30 years (1972-2007) were described. Related to the warming of WAP waters, the retreat of sea-ice was happening earlier each decade in the WAP. The observed changes in these environmental parameters offer a new temporal window for primary production. Indeed, the annual primary production increased from 1997 to 2007, in relation with the sea-ice cover anomaly for the previous winter. In addition, daily primary production was negatively and positively correlated to, respectively, sea-ice cover and sea-water temperature from September to November and from February to March, suggesting that regional warming favoured more primary production during spring and fall. On the contrary, the early retreat of sea-ice in spring, in coincidence with the spring ozone layer breakdown, led to an increase in photoinhibition (with an average of 11.6 ± 2.8 % of the daily primary production being photoinhibited). Therefore, regional climatic changes in the WAP had both a positive and a negative impact on primary production.The microbial community variability was also described in the Melchior Archipelago (in the WAP) from fall to spring 2006. Because of the extreme environmental conditions, the microbial community abundance and biomass were low in fall and winter and the community was dominated by small cells (< 2 µm), hence by a microbial food-web. Indeed, phytoplanktonic biomass was low during fall and winter (with respective chlorophyll a concentration, Chl-a, of 0.3 and 0.13 µg l-1). Phytoplankton biomass increased in spring (with a maximum Chl-a of 1.13 µg l-1) but, despite favourable growth conditions, phytoplankton was still dominated by small cells (2-20 µm), hence by a microbial or multivorous food-web. In addition, the early retreat of sea-ice in the spring 2006 exposed the WAP waters to strong ultraviolet B radiations (UVBR, 280-320 nm) that had a negative impact on the microbial community in surface waters.Finally, the relationship between air-sea CO2 and O2 exchanges in the WAP with the phytoplankton community biomass and composition and with the microbial community primary production and respiration was described. A positive relationship existed between Chl-a and the proportion of diatoms in the phytoplankton community. In addition, a negative relationship existed between Chl-a and ΔpCO2. The net community production (NCP) was mainly controlled by primary production and was negatively and positively related to ΔpCO2 and the %O2 saturation, respectively, suggesting that primary production was the main driver of air-sea CO2 and O2 gas exchanges in the WAP. In addition, the average ΔpCO2 for the summers and falls 2002 to 2004 was -20.04 ± 44.3 µatm, leading to a potential CO2 sink during this period in the WAP. The southern WAP was a potential CO2 sink (-43.60 ± 39.06 µatm) during fall while the northern part of the Peninsula was mainly a potential CO2 source during summer and fall (-4.96 ± 37.6 and 21.71 ± 22.39 µatm, respectively). The higher Chl-a concentrations measured in the southern WAP may explain this spatial distribution.

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this Dissertation were identified events of influence of the Antarctic ozone hole over the South of Brazil that occurred in the period between 1979 and 2011. For this, we analyzed the daily average data of total ozone column obtained through the Brewer Spectrophotometers MKIV #081 model during the period 1992-2000, MKII model #056 of 2000-2002 and MKIII #167 model from 2002 to the present day, installed in the Southern Space Observatory- OES/CRS/INPE MCTI (29,4 °S; 53,8°O; 488,7m) and by satellite instruments Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) to the same latitude of the southern Space Observatory in the absence of surface equipment data, searching for days of falls in ozone content. For these days, isentrópicas analyses were conducted of potential vorticity using Reanalysis data provided by the National Centers for Environmental PredictionAtmospheric Research (NCEPNCAR), in order to verify the origin of ozone-poor air mass. Confirmation of the origin of polar air masses took place through the analysis of the trajectories retroactive made through the Hysplit model of NOAA. In addition, it was also conducted a complementary analysis through the pictures of the ozone content of TOMS and OMI, the ozone hole in the Antarctic region and its connection to the South of Brazil. The methodology used was effective in the identification of 66 events of the Influence of Antarctic Ozone Hole over south of Brazil, which showed an average drop of 8.66 ± 3.13 in the ozone content. The identification of the stratospheric circulation pattern through the medium of the vorticity field potential for the occurrence of the phenomenon was performed. In addition, were shown an analysis of synoptic weather troposphere during the occurrence of two events, noting that in both cases, the events occurred in a situation front post on the South of Brazil, coupled with the passage of the input region polar polar or subtropical jet stream, characterized by the occurrence of the event of the tropopause folding where stratospheric air intrusion occurs in the troposphere, and advancement of a high-pressure front post system that prevents the formation of significant cloud cover. Leveraging the operating environment of the Atmospheric Modeling Group (GRUMA) at the Federal University of Santa Maria (UFSM), using data from the output of numerical weather forecasting model Global Forecast System (GFS) in making maps of potential vorticity, can carry out effectively the clue of the forecast arrival of stratospheric air masses of polar origin on the southern Brazil during the spring of the year of 2012 with at least four days in advance, coinciding with the events of transport these side effects of the Antarctic ozone hole over the South of Brazil identified in the current year. / Na presente Dissertação foram identificados os eventos de Efeito Secundário do Buraco de Ozônio Antártico ocorridos sobre o Sul do Brasil no período entre 1979 e 2011. Para isso, foram analisados os dados médios diários da coluna total de ozônio obtidos através dos Espectrofotômetros Brewer modelo MKIV #081 durante o período de 1992 2000, modelo MKII #056 de 2000 2002 e modelo MKIII #167 de 2002 até os dias atuais, instalados no Observatório Espacial do Sul OES/CRS/INPE MCTI (29,4 °S; 53,8°O; 488,7m) e pelos instrumentos de satélite Total Ozone Mapping Spectrometer (TOMS) e Ozone Monitoring Instrument (OMI) para a mesma latitude do Observatório Espacial do Sul na falta de dados do equipamento de superfície, buscando dias de quedas no conteúdo de ozônio. Para estes dias, foram realizadas análises isentrópicas de vorticidade potencial utilizando dados de reanálise fornecidos pelo National Centers for Environmental Prediction/Atmospheric Research (NCEP/NCAR), a fim de verificar a origem da massa de ar pobre em ozônio. A confirmação da origem polar das massas de ar deu-se através da análise das trajetórias retroativas confeccionadas através do modelo Hysplit da NOAA. Além disso, foi também realizada uma análise complementar através das imagens do conteúdo de ozônio dos satélites TOMS e OMI, verificando-se a atuação do Buraco de Ozônio na região Antártica e sua conexão com o Sul do Brasil. A metodologia empregada mostrou-se eficaz na identificação de 66 eventos de Efeito Secundário do Buraco de Ozônio Antártico sobre o Sul do Brasil, os quais apresentaram uma queda média de 8,66 ± 3,13 % no conteúdo de ozônio. Foi realizada a identificação do padrão de circulação estratosférica através da confecção do campo médio da vorticidade potencial para os dias de ocorrência do fenômeno. Além disso, foram mostradas as analises das condições sinótica troposférica durante a ocorrência de dois eventos, observando-se que em ambos os casos, os eventos ocorreram em uma situação pós frontal sobre o Sul do Brasil, associada à passagem da região de entrada polar da corrente de jato subtropical ou polar, caracterizada pela ocorrência de evento de quebra da tropopausa onde ocorre intrusão de ar estratosférico para dentro da troposfera, e avanço de um sistema de alta pressão pós frontal que impede a formação de nebulosidade significativa. Aproveitando o ambiente operacional do Grupo de Modelagem Atmosférica (GRUMA) da Universidade Federal de Santa Maria (UFSM), utilizando dados da saída do modelo de previsão numérica de tempo Global Forecast System (GFS) na confecção de mapas de vorticidade potencial, pode-se realizar eficazmente a previsão do indício da chegada de massas de ar estratosféricas de origem polar sobre o Sul do Brasil durante o período da primavera do ano de 2012, com pelo menos quatro dias de antecedência, coincidindo estes transportes com os eventos de Efeito Secundário do Buraco de Ozônio Antártico sobre o Sul do Brasil identificados no corrente ano.