Anàlisi de velocitats en boies de deriva - El problema de detectar la presencia de l'àncora de capa

Treball final presental per n'Ignasi Berenguer Vallès Casanova pel Màster en Canvi Ambiental: Anàlisi i Gestió de la Universitat de Girona (UdG), realitzat sota la direcció del Dr. José Luís Pelegrí Llopart de l'Institut de Ciències del Mar (ICM-CSIC) i de la Dra. Maria Elena Roget Armengol de la Universitat de Girona (UdG).-- 51 pages[EN] Satellite tracked drifting buoys are a useful lagrangian method of studying ocean surface currents and gaining a better understanding of ocean and climate dynamics. Drifting buoys usually have drogues at 15m depth in order to minimize direct wind force. Recent studies detected anomalous trends in data pertaining to the Global Drifter Program suggesting the presence of undrogued buoys in the drifter database even though the buoys were previously believed to be drogued with submergence or tether sensor. Recently, some methods have been developed to detect drogue loss by analysing the correlation between drifter velocities and wind force using altimetry data. However, the results are not useful for weak wind regions such as subtropical gyres. This study proposes a method of analysing drifter velocity time series so as to detect possible drogue loss events in buoys deployed in the North Atlantic Subtropical Gyre zone during the SPURS campaign in 2013 without using any other external data. The results show a potential methodology to keep working with and an interesting way of describing ocean surface dynamics[CAT] Les boies de deriva posicionades per satèl·lit són un mètode lagrangià útil per caracteritzar corrents oceàniques superficials i avançar en la comprensió de la dinàmica del clima i l’oceà. Les boies de deriva normalment tenen una àncora de capa a una profunditat de 15 m per minimitzar l’efecte directe del vent. Estudis recents han detectat que el conjunt de dades proporcionades per el Global Drifter Program contenen error acumulat fruït de boies que han estat erròniament classificades amb presència d’àncora, tot i l’ús d’un sensor de tensió. Recentment s’han desenvolupat metodologies per detectar la pèrdua d’àncora de capa que es basen en un anàlisi de correlació entre les velocitats de les boies i el vent en superfície utilitzant dades altimètriques. Tot i així, els resultats no són útils per zones de vents dèbils com el girs subtropicals. Aquest treball presenta una metodologia basada en l’anàlisi de les sèries de temps de velocitat de les boies per detectar la pèrdua d’àncora de capa en boies llançades el Gir Subtropical Nord Atlàntic durant la campanya SPURS del 2013 sense utilitzar altres fonts de dades. Els resultats mostren el potencial de la metodologia que es presenta per seguir treballant i una manera interessant de descriure la dinàmica superficial de l’oceàPeer Reviewe

Development of a citizen monitoring program for the Barcelona coastal waters: The Scientific Patí Vela (Patí Científic)

Special issue 9th MARTECH: International Workshop on Marine Technology: 16-18 June 2021, Vigo, Spain.-- 2 pages, 2 figuresThe first results of the PATI CIENTIFIC project are presented. This is a collaborative project funded by a Barcelona Institute of Culture’s grant for research and innovation under the 2019 Barcelona Science Plan. The main objective of this project is to develop a monitoring program for the coastal waters of Barcelona through a small-sailboat feet of the traditional and sustainable Patí de Vela (sailing skate). This pleasure boat is to become a scientifc sailing skate. This feet will acquire the essential oceanographic variables along the Catalan coast, which will be incorporated and accessible in a web platform. We present the initial adaptations done to the Patí de Vela to have an onboard platform holding the scientifc instruments (sensors and devices) for sampling the Barcelona coastal waters. These adaptations allow the systematic measurements of the essential physical and biogeochemical variables. These data, which will allow detecting variations along the coast, hence identifying potential sources of contamination and also providing the necessary knowledge of natural and anthropogenic seasonality, and will be freely available on a web platform. The PATI CIENTIFIC project will increase our knowledge of the coastal waters of the Barcelona coast, encouraging participation in sea monitoring activities and increasing social awareness on the need to love and protect our oceansThe work of Raul Bardaji is supported by the CSIC Intramural Project EMSO – Laboratorios Submarinos Profundos. The work of Carlos Rodero is supported by the H2020 Project MONOCLE (grant agreement No 776480

Barcelona Coastal Monitoring with the “Patí a Vela”, a Traditional Sailboat Turned into an Oceanographic Platform

Special issue Technological Oceanography.-- 16 pages, 12 figures, 3 tables.-- Data supporting reported results can be found at https://paticientific.org/index.php/dades/ (accessed on 13 April 2022) and through https://zenodo.org/search (accessed on 13 April 2022) by searching “pati cientific”.Shelf waters near large cities, such as Barcelona, are affected not only by meteorological episodes but also by anthropogenic influence. Scientists usually use data from on-site coastal platforms to analyze and understand these complex water ecosystems because remote sensing satellites have low spatiotemporal resolution and do not provide reliable data so close to the coast. However, platforms with conventional oceanographic instrumentation are expensive to install and maintain. This study presents the scientific adaptation and initial measurements from a “patí a vela”, which is a very popular unipersonal catamaran in Barcelona. This versatile sailing vessel has been adapted to contain several low-cost sensors and instruments to measure water properties. Here, we describe the setup of a multi-parameter prototype, and then focus on results obtained using a low-cost temperature profiler. First, the temperature data are compared and validated with another conventional oceanographic instrument used in monthly oceanographic cruises. Then, field measurements between July and November 2021 are used to explore the relationship between air and water temperature in the Barcelona coastal area, showing the seasonal evolution of the temperature profile. We conclude that citizen sampling from fully sustainable sailing boats may turn into an effective strategy to monitor the urban coastal watersThis work has been carried out within the framework of the 2019 Barcelona Pla de Ciència, with funding from the Barcelona City Council through the project “Development of a citizen monitoring program for the Barcelona coastal waters: the Scientific Patí Vela” (PATI CIENTIFIC; references 19SO1645-006, 19SO1649-006, 19SO1651-006). [...] The ICM authors also recognize the institutional support of the Spanish Government through the Severo Ochoa Center of Excellence accreditation (CEX2019-000928-S)Peer reviewe

Taking The Pulse of the Ocean

Jornada d'Investigadors Predoctorals Interdisciplinària (JIPI), 9 February 2017, BarcelonaIn medicine, taking the pulse is a basic method when evaluating the blood circulation in specific points of the human body. Similar to blood circulation distributing different essential properties throughout our body, ocean circulation distributes key properties for life in our blue planet. The ocean holds most of the water, heat, inorganic carbon and nutrients, and life in our planet, and the ocean currents are a major responsible for redistributing most of these properties, hence the extraordinary relevance of their proper measurement. What tools do we use to measure ocean circulation? Where are the best regions to measure the ocean¿s pulse? Nowadays a wide range of observational methodologies exist, including classic oceanographic cruises, remote sensing, numerical models, and autonomous Eulerian and Lagrangian systems. The appropriate application and combination of these techniques helps evaluate how ocean circulation may be evolving under the current scenario of climate change. Here we present how our research team takes the Pulse of the Ocean, showing some of our ongoing activities in key regions such as the Tropical and South Atlantic Oceans. We will describe how the data are gathered and will also provide examples on how its analysis leads to a better understanding of the spatial and temporal variability of the ocean circulation system. We will also illustrate the activities carried out during an oceanographic cruise with the upcoming RETRO-BMC cruise, to be carried next April in the Brazil-Malvinas Confluence region, in the western South Atlantic OceanPeer Reviewe

Patí Científic - El far

Nova sessió del podcast realitzat amb la col·laboració de l'Institut de Ciències del Mar. Coneixem el projecte "patí científic" i la tasca que desenvolupa. Per fer-ho ens acompanyen Ignasi Vallès, oceanògraf i Oriol Carrasco, patinairePeer reviewe

Un grupo de investigadores del Instituto de Ciencias del Mar de Barcelona ha tranformado un patín de vela en una embarcarción para la investigación oceanográfica

Peer reviewe

Retroflections in the Tropical Atlantic Ocean

Memoria de tesis doctoral presentada por Ignasi Berenguer Vallès Casanova para obtener el título de Doctor en Ciències del Mar por la Universitat Politècnica de Catalunya (UPC), realizada bajo la dirección del Dr. Josep Lluís Pelegrí del Institut de Ciències del Mar (ICM-CSIC).-- 143 pages, figures, appendix[EN] In the tropical Atlantic, the upper ocean circulation is the area of confluence of two major vertical cells: the large-scale overturning Atlantic Meridional Overturning Circulation (AMOC) and the regional relatively shallow Subtropical Cells (STCs). Both meridional cells interact in a complex system of zonal currents driven by fluctuations of the trade winds. The thermocline waters that subduct in the subtropical South Atlantic join the northward AMOC limb in the western boundary North Brazil Current (NBC). When the NBC crosses the equator it retroflects forced by fluctuations in the easterly winds. These changes in the wind field are part of coupled ocean-atmosphere variations that span across the entire Atlantic and cover a wide range of timescales. The present thesis aims at describing the NBC retroflection in the equatorial band and improving our current knowledge on the upper-ocean circulation in the tropical Atlantic and its interaction with the climate variability. The NBC system carries warm and highly saline waters from the subtropical gyre to the tropics, for a total of 38.5 Sv and 2.0 PW, in what represents the main AMOC cross-equatorial pathway. This subtropical-tropical transfer accounts for water-mass and heat contributions coming from the eastern subtropical boundary (14.9 Sv, 0.82 PW) and the interior subtropical gyre (7.4 Sv, 0.28 PW). As an opposite path, shallow tropical waters transfer 1.4 Sv and 0.14 PW to the subtropics. Adding interior pathways and tropical recirculation transports, a total of 20.6 Sv and 1.0 PW are effectively exported northward through 5°S. As the NBC crosses the equator, 11.4±1.3 Sv of South Atlantic waters retroflect into the eastward Equatorial Undercurrent (EUC) at 32°W, which join 2.8±0.4 Sv arriving from the northern hemisphere. The NBC-EUC retroflection takes place at different latitudinal bands. Most of the waters turn eastward south of 3°N (7.2±0.6 Sv) but a substantial amount does so north of this latitude (5.1±0.4 Sv). The variability of the EUC transport at 32°W is characterized by principal spring and secondary fall monthly-mean maximum, with the fall maximum only present in the northern retroflection. At interannual scales the EUC transport shows a weak yet significant correlation with the Atlantic Niño index, and reflects a major increase in the contribution from the South Atlantic tropical waters during 2008-2016 as compared with 1997-2007. The NBC retroflection occurs within an area where changes in Sea Surface Height (SSH) anomalies (SSHA) respond to the two main modes of Tropical Atlantic Variability (TAV): the Meridional Mode (MM) and Equatorial Mode (EM). During the development of warm (cold) MM events, all North Equatorial Countercurrent (NECC), EUC and north South Equatorial Current (nSEC) intensify (weaken). Conversely, during the decaying phase, anomalous wind curl north of the equator, triggers a downwelling (upwelling) Rossby wave that propagates westward and is reflected at the South American coast. The resultant downwelling (upwelling) Kelvin wave reverses the equatorial zonal gradients in boreal summer, weakening (strengthening) both equatorial nSE and EUC. The activation of the RW-reflected mechanisms shifts the zonal SSHA, enhancing (weakeking) the nSEC and favoring the termination of the EM event. Remarkably, the EUC displays a non-linear response probably as a result of external forcings and/or the intrinsic diversity of the EM. The development of warm EM is accompanied by an anomalous reduction (intensification) of equatorial nSEC and NECC during boreal spring. The diversity of EM has been studied by applying an empirical orthogonal function (EOF) analysis of a sample of 22 time series of warm EM events (referred as Atlantic Niño). This technique reveals four different types of spatio-temporal distributions of SST anomalies (SSTA) in the equatorial Atlantic in the period 1982-2019. Early-terminanting and persistent categories are associated with different dissipation times for the Atlantic Niño. While early-onset and late-onset refers to the diverse Atlantic Niño timings found in the sample. These four different types of Atlantic Niño are associated with different climatic response on the surrounding continents. Interestingly, early-terminating, persistent and early-onset Atlantic Niño seem to be preceded by local (i.e: MM) and remote (i.e: ENSO) forcings in boreal spring. While, late-onset Atlantic Niño is more related with internal variability[CAT] La circulació oceànica a les capes superiors de l’Atlàntic tropical es caracteritza per la confluència de dos importants sistemes de circulació meridional: la circulació meridional de gran escala de l’Atlàntic (AMOC, per les seves sigles en anglès) i el sistemes regionals de cèl·lules subtropicals (STCs). Ambdues cèl·lules circulatòries interactuen en un complex sistema de corrents zonals governat pel patró de vents alisis. Les aigües que convergeixen al subtròpic de l’Atlàntic Sud per bombament d’Ekman es situen a la termoclina i retornen cap a l’equador, juntament amb la branca de retorn de la AMOC. Les dos aigües conflueixen al marge occidental constituint el sistema de corrents nord del Brasil (NBUC/NBC). Quan la NBC creua l’equador esdevé inestable per l’absència de Coriolis i es sotmesa als gradients d’altura de la superfície del mar (SSH) associats amb el sistema de vents de component est. Part de la NBC es desenganxa del talús per alimentar les diferents corrents zonals esdevenint un important sistema de retroflexió. La variabilitat d’aquesta retroflexió està per tant lligada a les oscil·lacions del camp de vent predominant i les modificacions associades dels gradients de SSH. Aquestes fluctuacions formen part d’un complex sistema acoblat entre l’atmosfera i l’oceà que es presenta a diferents escales temporals i espacials. L’objectiu d’aquesta tesi és descriure el sistema de retroflexió a la banda equatorial i millorar el nostre coneixement sobre la interacció entre aquest sistema de corrents de les capes superficials i termoclina amb diferents modes de variabilitat climàtica. El sistema NBC/NBUC transporta un total de 38.5 Sv i 2.0 PW d’aigües relativament salines del gir subtropical de l’Atlàntic Sud que representen el principal camí de retorn de la AMOC. Aquesta transferència subtropical-tropical conté aigües del marge meridional (14.9 Sv, 0.82 PW) i aigües interiors de la conca subtropical (7.4 Sv, 0.28 PW). Per altra banda, aigües de capes superficials provinents del gir tropical es traspassen al gir subtropical amb un total de 1.4 Sv i 0.14 PW. Tenint en compte aquest traspàs, i la recirculació tropical, el resultat es un transport net en direcció nord de 20.6 Sv i 1.0 PW a 5°S. Un cop la NBC creua l’equador 11.4 ± 1.3 Sv de l’Atlàntic Sud alimenten la corrent equatorial situada a la capa de la termoclina (EUC) a 32°W. Aquestes aigües es sumen als 2.8 ± 0.4 Sv provinents de l’hemisferi nord. La retroflexió NBC-EUC es dona lloc a diferents bandes latitudinals al voltant de l’equador. La majoria d’aigües giren en direcció est per sota els 3°N (7.2 ± 0.6 Sv) però una important contribució es dona lloc més al nord (5.1 ± 0.4 Sv). La variabilitat de la EUC a 32°W està caracteritzada per dos màxims a la primavera i tardor boreal. Però el màxim de tardor només es troba present en les aigües del gir més septentrional. A escala interanual, el transport de la EUC mostra una correlació negativa dèbil però significativa amb l’índex de l’Atlàntic Niño i curiosament presenta una tendència positiva entre el període 2008 al 2016 en comparació amb el període 1997-2007. La retroflexió de la NBC es dona lloc en una àrea on canvis anòmals en l’altura de la superfície del mar (SSHA) responen als dos modes principals de variabilitat climàtica interanual de l’Atlàntic tropical (TAV): el mode meridional (MM) i el mode equatorial (EM), aquest últim conegut també com Atlantic Niño/Niña. Durant el desenvolupament d’un episodi positiu (negatiu) de MM la contracorrent nord equatorial (NECC), EUC i la branca nord de la corrent sud-equatorial (nSEC) s’intensifiquen (es debiliten). Contràriament, durant el decaïment del MM el mecanisme de reflexió d’ona Rossby (RW) al marge occidental esdevé en ona Kelvin que es propaga cap a l’est al llarg de l’equador. Quan arriba al marge oriental de l’Atlàntic tropical la situació es reverteix desenvolupant una zona de convergència o divergència respectivament que equivaldria a EM positiu (negatiu). Tant la corrent superficial nSEC com la NECC es debiliten en situacions de EM positiu, contràriament la EUC no mostra una resposta linear indicant possibles forçaments externs o una alta diversitat dels episodis de EM. En aquest sentit la diversitat d’episodis positius de EM, anomenats també Atlantic Niño, han estat estudiats aplicant anàlisi de funcions ortogonals en una sèrie temporal de 22 casos. Els resultats mostren quatre tipus de distribució en l’espai-temps d’anomalies de temperatura superficial del mar (SSTA) a l’Atlàntic equatorial. La classificació és en funció del temps en que apareixen i la seva extensió temporal i espacial. Cada un d’aquest quatre tipus d’Atlàntic Niño està associat a una resposta climàtica a les zones continentals del nord-est d’Amèrica del Sud i l’Àfrica Occidental. Curiosament, tres dels quatre tipus s’expliquen per les condicions prèvies locals (i.e: MM) i remotes (i.e: ENSO) durant la primavera anteriorThe development of this thesis have been funded by: • FPI contract BES2015-071314 as part of VADERETRO project. Ministerio de Economia y Competitividad • VADERETRO. Western boundary retroflections. Ref.: CTM2014-56987-P. Ministerio de Economia y Competitividad. • Pati Científic. Development of a citizen monitoring program for the Barcelona coastal waters, www.paticientific.org. Ref. 19S01645-006. Institut de cultura de Barcelona. Ajuntament de Barcelona. • SAGA. South Atlantic Gate-Away. Ref.: RTI2018-100844-B-C33. Ministerio de Economia y Competitividad. • CLIMATE-COVID19. Ref.: PIM-E-202030E222Peer reviewe

Lagrangian stream-functions and transit times

International Workshop on Marine Pollution and Maritime Safety (MAPMAS), 3-6 October 2017, BarcelonaThe Lagrangian approach is the natural way to describe ocean circulation pathways and connectivities at different scales. Nowadays, a variety of open-source Lagrangian modules are used by the oceanographic community to analyze ocean velocity data, either from observations or model outputs, in order to identify the predominant water pathways and mean transit times. This methodology can help understand how biotic and abiotic properties as well as pollutants, such as micro-plastics, are distributed in the ocean, and may also be used to assess the probability function of finding a drifting object at a certain location after a given time interval. Here we illustrate the methodology using the Connectivity Modelling System (Paris et al., Environt Model Soft, 42- 47-54, 2014) applied to two velocity fields, with different spatial and temporal resolutions. The first one is the two dimensional GLORYS2v4 reanalysis velocity field, with gridded velocity data at 1/4º of resolution and daily outputs between 1995 and 2015. The second one is a monthly Argo-inferred surface velocity field with 1º resolution (Rosell-Fieschi et al., Progr Oceanogr, 130, 1-18). We will present several examples with the surface velocity fields for the tropical Atlantic and South Atlantic Oceans and discuss the potential of the method, where its diverse applications are limited by the temporal and spatial resolution of the velocity fields.Peer Reviewe

Ciencia a Vela

Taller virtual pàra la Semana de la Cienci

Científics de l'Institut de Ciències del Mar mesuren la contaminació i els efectes del canvi climàtic gràcies a un patí català

La pressió a què estan sotmesos els oceans, a causa de la contaminació i el canvi climàtic, preocupa molt els científics de tot el món. A Barcelona, on el litoral rep una pressió tan forta, els científics necessiten recopilar dades continuades per seguir el seu estat i proposar mesures de millora. L'Institut de Ciències del Mar ha iniciat un curiós projecte per aconseguir que siguin els mateixos ciutadans els qui els ajudin a recopilar aquestes dadesPeer reviewe