Francisco de Mélo Virissimo

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Produções bibliográficas

• DE MELO VIRÍSSIMO, FRANCISCO ; MILEWSKI, PAUL A. . Nonlinear stability of two-layer shallow water flows with a free surface. PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES , v. 476, p. 20190594, 2020.

• DE MELO VIRISSIMO, F. ; MILEWSKI, P. A. . Threelayer flows in the shallow water limit. Studies in Applied Mathematics , v. 142, p. 487-512, 2019.

Outras produções

Projetos de pesquisa

• 2018 - Atual

  CUSTARD (Carbon Uptake and Seasonal Traits in Antarctic Remineralisation Depth), Descrição: The Southern Ocean plays a pivotal role in the global carbon cycle via the upwelling of waters rich in CO2 which then exchange carbon with the atmosphere through a variety of processes. The sum total of these processes contribute to regulating the future evolution of our climate yet are poorly understood and quantified - factors which contribute to significant uncertainty in our ability to predict future climate. CUSTARD (Carbon Uptake and Seasonal Traits of Antarctic Remineralisation Depth) is a large and multidisciplinary project focussed on understanding a key element of this problem. The overall objective is to understand how surface biogeochemistry (particularly of iron and silicate), physical circulation and plankton stoichiometry control the remineralisation depth of sinking organic material; a parameter which we know regulates air sea CO2 partitioning yet one for which we still have a poor understanding. Preliminary model experiments conducted for this proposal suggest that it is particularly important to understand this interplay between circulation and remineralisation in the northern part of the Southern Ocean, where water upwelled at the Polar Front is advected north in the surface before being subducted at the northern boundary of the Southern Ocean. Sinking material produced in this region can, depending on its depth of remineralisation, either be retained within this so-called 'upper limb' of the Southern Ocean circulation or alternatively, if remineralised deep, enter the 'lower cell' and exit the Southern Ocean at depth. A key difference between the two pathways is the length of time that the carbon they retain is locked away from the atmosphere; hence understanding what regulates the fate of this carbon and how it may change into the future is critical to predicting the future evolution of our climate. We will address our overall objective by focussing on an important region of the upper limb in the southeast Pacific which is a key area for the formation of water masses subducted northwards and a major route out of the Southern Ocean for carbon. We will tackle this using an innovative combination of modelling and fieldwork, using gliders and novel nutrient sensors, and forging a collaboration with the US Ocean Observatories Initiative. In particular, we will address the following objectives: 1. To obtain an accurate picture of the seasonal air-sea CO2 flux and macronutrient drawdown 2. To quantify the link between iron and silicate availability and remineralisation depth 3. To observationally determine the seasonal cycle in remineralisation depth 4. To examine the link between seasonality in remineralisation depth and the trajectory of carbon from the surface out of the upper limb. By delivering these objectives we will address the following hypotheses: H1: There is a strong seasonal cycle in remineralisation depth driven by seasonal variability in surface silicate:carbon:nitrogen uptake as a function of iron availability H2: This seasonal cycle in remineralisation depth leads to seasonal variability in the fate of organic carbon leaving the Southern Ocean via the upper limb. , Situação: Em andamento; Natureza: Pesquisa. , Integrantes: Francisco de Melo Viríssimo - Integrante / Richard Sanders - Integrante / Stephanie Henson - Integrante / Sarah Giering - Integrante / Adrian Martin - Coordenador / Andrew Yool - Integrante / Nathan Briggs - Integrante / Filipa Carvalho - Integrante / Heather Bouman - Integrante / Hugh Venables - Integrante / Alexander David Beaton - Integrante / Peter Brown - Integrante / Antony Birchill - Integrante / Geraldine Clinton-Bailey - Integrante / Simon Ussher - Integrante / Angela Milne - Integrante / Dorothee Bakker - Integrante / Gareth Lee - Integrante / Christopher Moore - Integrante / Thomas Bibby - Integrante / Peter Landschützer - Integrante / Violetta Paba - Integrante.

• 2017 - Atual

  TICTOC (Transient tracer-based Investigation of Circulation and Thermal Ocean Change), Descrição: The Ocean takes up 93% of the additional heat in the climate system that results from greenhouse gas forcing. This warming and consequent expansion of the water results in global sea level rise. However, the strength of ocean warming and sea level rise varies regionally. Patterns of regional oceanic temperature change reflect not only the heat absorbed due to global warming (the added heat) but also the redistribution of ocean water masses by variability in circulation. Redistribution of heat by ocean circulation is the leading source of uncertainty in projections of future regional sea level rise by the end of this century. The aim of TICTOC is to quantify recent changes in the uptake and redistribution of heat by the ocean using observations and models and the transient tracer-based approach, enabling improved projections of future climate and its regional impacts. The new approach will separate warming into an added temperature change (the direct response to increasing radiative forcing) and a redistributed change (largely due to circulation changes). The decomposition is analogous to the separation of oceanic carbon content into "anthropogenic" and "natural" changes. We will use a framework that has been developed in the climate modelling community, treating heat as a passive tracer. We will make a novel application of this framework to observations using the passive nature of transient tracers (CFCs and SF6) and carbon isotopes. The size, strength and evolution of the passive tracer (determined by our analysis of observations and forced ocean models) will be used to improve model projections of sea level change. TICTOC will deliver observational constraints on the distinct processes by which heat is redistributed by the ocean, allowing for both quantification of recent warming and understanding of its drivers. New ship-based observations of transient tracers will be conducted in the Atlantic Ocean. Using the new and existing observations, thermodynamic and inverse theory, and current activities in CMIP6, we will provide a global view of the added and redistributed temperature change. We will analyse regional temperature and consequent thermosteric sea level changes and use our observational description of the recent past to constrain projections of future regional sea level change.. , Situação: Em andamento; Natureza: Pesquisa. , Integrantes: Francisco de Melo Viríssimo - Integrante / Adrian Martin - Integrante / Peter Brown - Integrante / Elaine McDonagh - Coordenador / George Nurser - Integrante / Alice Marzocchi - Integrante / Louis Clément - Integrante / Cristian Florindo Lopez - Integrante / Andy Watson - Integrante / Marie-José Messias - Integrante / Genevieve Hinde - Integrante / Gary Murphy - Integrante / Jack Hughes - Integrante / Jessica Thorn - Integrante / Jonathan Gregory - Integrante / Laure Zanna - Integrante / Samar Khatiwala - Integrante / Heather Graven - Integrante / Mike Meredith - Integrante / Jan Zika - Integrante / Matt Palmer - Integrante / Bob Key - Integrante.

• 2017 - Atual

  GOCART (Gauging ocean Organic Carbon fluxes using Autonomous Robotic Technologies), Descrição: Climate change driven by CO2 emissions from human activities is a significant challenge facing mankind. An important component of Earth's carbon cycle is the ocean's biological carbon pump; without it atmospheric CO2 would be ~50% higher than it is now. The biological carbon pump consists of sinking organic matter which is remineralised back into CO2 in the deep ocean. The depth at which remineralisation occurs is the main factor affecting the amount of organic carbon stored in the ocean. Currently we do not understand how or why remineralisation depth varies in time, which limits our ability to make robust predictions of how the future carbon cycle, and hence our climate, will change into the future. This is mainly due to the challenges of measuring remineralisation depth using conventional methods - a barrier which autonomous underwater vehicles, such as gliders, are able to overcome by providing high frequency data over long periods. In GOCART, glider deployments will be used to establish the characteristics and significance of temporal variability in organic carbon flux and remineralisation depth. This will give new insights into the factors driving variability in remineralisation depth, ultimately leading to development of a new model parameterisation incorporating temporal variability. GOCART represents a significant advance in quantifying temporal variability in remineralisation depth, which is key to reducing uncertainty in model predictions of ocean carbon storage, and yet currently almost entirely unknown. Phase 1 will involve deploying gliders in the Southern Ocean near South Georgia in collaboration with the COMICS programme.. , Situação: Em andamento; Natureza: Pesquisa. , Integrantes: Francisco de Melo Viríssimo - Integrante / Stephanie Henson - Coordenador / Nathan Briggs - Integrante / Filipa Carvalho - Integrante.

• 2017 - Atual

  COMICS (Controls over Ocean Mesopelagic Interior Carbon Storage), Descrição: COMICS is a four-year collaborative research project that aims to quantify the flow of carbon in the ocean?s 'twilight' zone in order to more accurately model global climate change. This 'twilight' zone is the part of the ocean between 100m and 1000m below the sea surface, where only a small amount of light from the sun can still penetrate. It is currently known that the efficiency of carbon transport from the atmosphere through this zone is key to regulating atmospheric CO2 levels. However, the processes that control the efficiency of biological storage of carbon in the deep ocean are not well known, which is an obstacle to predicting how they may change. By investigating carbon dynamics in the ocean interior, COMICS will help to improve predictions of future global climate change. By building on previous work with new data from two research cruises and exploiting new technologies COMICS will shed light on carbon transport processes in the twilight zone. COMICS will integrate modelling and new data from two research cruises in the tropical Atlantic and Southern Ocean. COMICS will make observations at sea of particle flux and quantify interior biological processes using stable isotopes. It will apply organic geochemical and molecular biological techniques to samples collected using nets and traps. The COMICS project will be led by the National Oceanography Centre and is a collaboration between the British Antarctic Survey and the universities of Queen Mary London, Liverpool, Oxford and Southampton. The project has received funding from the Natural Environmental Research Council and will run between April 2017 and 2021.. , Situação: Em andamento; Natureza: Pesquisa. , Integrantes: Francisco de Melo Viríssimo - Integrante / Richard Sanders - Coordenador / Stephanie Henson - Integrante / Richard Lampitt - Integrante / Alex Poulton - Integrante / Dan Mayor - Integrante / Geraint Tarling - Integrante / Sarah Giering - Integrante / Tom Anderson - Integrante / Adrian Martin - Integrante / Andrew Yool - Integrante.

• 2014 - 2018

  Dynamical Systems Methods for Waves in Fluids: Stability, Breaking and Mixing, Descrição: O presente projeto de pesquisa visa a obtenção de resultados matemáticos de real aplicação ao problema da evolução de ondas de agua rasa (aquelas com grande comprimento de onda) em estratificações, com foco em duas e três camadas. Escoamentos com estratificação (i.e., escoamentos nos quais a densidade do fluido varia verticalmente) são primordiais em geofísica, uma vez que sua dinâmica é responsável por uma grande parte dos fenômenos atmosféricos e oceânicos observados. Um aspecto importante das estratificações é a existência do movimento de ondas internas, devido a forca restauradora de empuxo. Tais ondas propagam energia sem o transporte apreciável de fluido e, portanto, são relevantes no balanço de energia realizado em pesquisas climáticas. Estudos matemáticos deste fenômeno são particularmente importantes, uma vez que o movimento de ondas não é previsto de forma satisfatória pela maioria dos modelos numéricos climáticos existentes, devido as suas rápidas escalas, e assim necessita ser entendido e parametrizado. Por exemplo, ondas podem quebrar e dissipar energia ou misturar os fluidos subjacentes e afetar o próprio meio em que elas estão propagando. Assim, essa investigação prevista nesse projeto não so aumentara a compreensão de ondas internas, mas também terá um impacto no desenvolvimento de futuros modelos climáticos. , Situação: Concluído; Natureza: Pesquisa. , Alunos envolvidos: Doutorado: (1) . , Integrantes: Francisco de Melo Viríssimo - Integrante / Paul Antoine Milewski - Coordenador.

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