Em escalas interanuais a advecção de calor, sal e nutrientes pode afetar a produtividade primária. Pode-se citar a Circulação de Revolvimento Meridional (MOC) no impacto da concentração de clorofila. Neste estudo, a partir do método Multidimensional Empirical Mode Decomposition foram obtidos tendências decadais de PAR, nitrato integrado na coluna d\'água, concentração de clorofila e fluxo de volume da MOC. Em variações de baixa frequência há uma relação entre o transporte de volume da MOC com o nitrato integrado na coluna d\'água no Atlântico Sul, e consequentemente, na concentração de clorofila. Dois possíveis cenários foram identificados sobre o efeito da MOC no nitrato integrado e na concentração de clorofila. O cenário 1 apresenta uma relação direta no sistema MOC-nitrato integrado-concentração de clorofila, enquanto o efeito do cenário 2 é indireto, com a MOC afetando outras variáveis que perturbam o sistema. Neste estudo também foi analisado a influência de teleconexões atmosféricas na MOC do Atlântico Sul. Foi achado indícios da influência da Oscilação Antártica na MOC do Atlântico Sul em escalas decadais. Conclui-se que variações de baixa frequência no fluxo de volume da MOC alteram o padrão espaço-temporal da concentração de clorofila no Atlântico Sul. / On interannual timescales the advection of heat, salt and nutrients can affect the primary production. The influence of the Meridional Overturning Circulation (MOC) over the chlorophyll concentration can be mentioned. In this study, decadal trends of PAR, integrated nitrate over the water column, chlorophyll and volume flux of the MOC were obtained using the Multidimensional Empirical Mode Decomposition method. On low frequency variations there is a relationship between the MOC volume transport with integrated nitrate over the water column in the South Atlantic, and therefore, on chlorophyll concentration. Two scenarios were identified as possible mechanisms of influence of the MOC over integrated nitrate and chlorophyll concentrations. Scenario 1 presents a direct relationship on the system MOC-integrated nitrate-chlorophyll concentration, while scenario 2 has an indirect effect, with the MOC affecting other variables that disturb the system. In this study the influence of atmospheric teleconnections on the South Atlantic MOC were also investigated. It was found evidence that the Antarctic Oscillation can affect the South Atlantic MOC on decadal timescales. It was concluded that low frequency variability on the volume flux of the MOC can alter the spatiotemporal pattern of the chlorophyll concentration on the South Atlantic.

In this project, we identified and examined the 50 coldest extreme temperature eventsin North America (CENA) and the 50 warmest extreme temperature events insouthwestern Europe (WEEU) during the winter seasons from 1948 to 2023. For theanalysis, we utilized daily NCEP-NCAR reanalysis data for temperature, sea levelpressure (SLP), and 500hPa geopotential height (Z500). Our main objective was toinvestigate the co-occurrence of CENA-WEEU events. To deepen our understandingof the recurrence of these events and their relationship with large-scale atmosphericpatterns and drivers, we examined the SLP and Z500 for the selected extreme events.The results revealed clear indications of an interconnection between CENA andWEEU. During the CENA, above-normal temperatures were observed over Europe,while negative temperature anomalies affected the eastern USA during the WEEU.This co-occurrence was further supported by the identification of seven CENA-WEEUextremes that occurred almost simultaneously. The findings regarding the large-scaleatmospheric drivers of these extremes align with previous studies. The CENAappears to be driven by an anomalous high ridge over the Gulf of Alaska and anortherly flow over North America, while the WEEU seems to be influenced by astrong, zonal and southerly shifted flow across the North Atlantic, associated with adeep trough over the British Isles and a ridge over the Mediterranean basin. Acommon feature of CENA-WEEU events is the presence of a negative North AtlanticOscillation (NAO)-like atmospheric pattern over the Atlantic Ocean prior to theiroccurrence.Despite the significant similarities between these events, some disparities relatedto the atmospheric flow and the magnitude of temperature anomalies in the twocontinents suggest the need for further investigation to enhance our understanding ofthe co-occurrence of CENA-WEEU events. / I detta projekt identifierades och studerades de 50 kallaste extrematemperaturhändelserna i Nordamerika (CENA) och de 50 varmaste extrematemperaturhändelserna i sydvästra Europa (WEEU) under vintersäsongerna från1948 till 2023. För analysen, användes dagliga NCEP-NCAR återanalys för demeteorologiska variablerna temperatur, tryck (SLP) och 500hPa geopotentialhöjd(Z500). Huvudsyftet med denna studie är att undersöka samförekomsten avCENA-WEEU-händelserna. För att fördjupa vår förståelse för återkommandehändelser och deras förhållande till storskaliga atmosfäriska mönster och drivkrafter,användes SLP och Z500 variablar för de utvalda extrema händelserna.Resultaten visade tydliga tecken på sammankoppling mellan CENA och WEEU.Temperaturer över det normala observerades över Europa under CENA, medannegativa temperaturanomalier påverkade östra USA under WEEU. Samförekomstenstöds ytterligare av identifieringen av sju CENA-WEEU-extremer som inträffadenästan samtidigt. När det gäller de storskaliga atmosfäriska drivfaktorer förextremerna, stämmer resultaten överens med tidigare studier. En starkhögtrycskrygg över Alaskagolfen och ett nordligt flöde över Nordamerika verkar drivaCENA, medan ett ett starkt, zon- och sydligt förskjutet flöde över Nordatlanten,associerat med intensiv cyklonaktivitet över de brittiska öarna och en högtrycksryggöver Medelhavsområdet, verkar vara källan till WEEU. Ett gemensamt drag förCENA-WEEU är förekomsten av ett negativt NAO-liknande atmosfäriskt mönster överAtlanten innan de inträffade.Trots de starka och många likheterna mellan händelserna, tyder vissa skillnaderrelaterade till atmosfärsflödet och extrema temperaturavvikelser på de bådakontinenterna, på behovet av ytterligare undersökningar för att fördjupa vår förståelseav samförekomsten mellan CENA och WEEU.