Person: Losada Doval, Teresa
Loading...
First Name
Teresa
Last Name
Losada Doval
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Física de la Tierra y Astrofísica
Area
Física de la Tierra
Identifiers
9 results
Search Results
Now showing 1 - 9 of 9
Item A shift in the wind regime of the southern end of the Canary upwelling system at the turn of the 20th century(Journal of geophysical research-oceans, 2021) Gallego, D.; García Herrera, Ricardo Francisco; Losada Doval, Teresa; Mohino Harris, Elsa; Rodríguez De Fonseca, María BelénIn this study, we make use of historical wind direction observations to assemble an instrumental upwelling index (DUI) at the southern end of the Canary Current Upwelling System. The DUI covers the period between 1825 and 2014 and, unlike other upwelling indices, it does not rely neither in wind speed nor in reanalyzed data. In this sense, the DUI can be regarded as an instrumental index. Additionally, it avoids the suspected bias toward increasing wind speed of historical wind observations documented in previous research. Our results indicate that the frequency of the alongshore winds at the west coast of Africa between 10°N and 20°N measured by the DUI is significantly related with the wind stress and therefore the upwelling intensity in this region. The DUI presents a significant variability both at interannual and decadal timescales. We have not found any significant trend for the 20th century. However, when the entire length of the series is considered, a large shift toward more frequent alongshore winds is evidenced as a result of several decade-long fluctuations which took place between the late 19th century and the beginning of the 20th century. This fact would imply that a significant change in the upwelling intensity at the southern end of the Canary Current Upwelling System should have occurred at the turn of the 20th century.Item Changes in interannual tropical Atlantic-Pacific basin interactions modulated by a South Atlantic cooling(Journal of climate, 2022) Losada Doval, Teresa; Rodríguez De Fonseca, María Belén; Mechoso, Roberto; Mohino Harris, Elsa; Castaño-Tierno, AntonioAlthough tropical interbasin interactions at interannual time scales are presently receiving much attention, their controlling factors and variations on longer time scales are under debate. Tropical convection plays a crucial role in the occurrence and nonstationarity of them. In this paper, we investigate the dependence of interannual tropical AtlanticPacific basin interactions on convection-related features of the tropical oceans’ climatology, especially the ITCZ position. Wecontrast a CGCM control simulation with an experiment in which tropical convection is modified by an artificial perturbation outside the tropics that reduces the incident shortwave radiation in a region of the South Atlantic. Based on previous work, this modification is expected to shift in latitude the climatological position of the simulated ITCZ. The experiment shows altered Walker circulations, stronger interannual variability over the tropical oceans, a westward extension of the Atlantic Ni˜no pattern and of convection, and shallower thermocline in the Pacific, making the basin more sensitive to both local and remote perturbations. As a consequence, the experiment shows enhanced interannual Atlantic–Pacificbasin interactions at the equator, and weaker teleconnections between the north tropical Atlantic and the equatorial Pacific. The latter seems to occur because the impact of the warm Atlantic SST anomalies is offset by the presence of warm SST anomalies in El Ni˜no region. Despite the uncertainties raised because the simulations are relatively short, we conclude that this work presents a potential explanation for the long-term changes in the tropical basin interactions and offers a novel and useful methodology for their analysis.Item Impact of equatorial Atlantic variability on ENSO predictive skill(Nature communications, 2021) Exarchou, Eleftheria; Ortega, Pablo; Rodríguez De Fonseca, María Belén; Losada Doval, Teresa; Polo Sánchez, Irene; Prodhomme, CloéEl Niño-Southern Oscillation (ENSO) is a key mode of climate variability with worldwide climate impacts. Recent studies have highlighted the impact of other tropical oceans on its variability. In particular, observations have demonstrated that summer Atlantic Niños (Niñas) favor the development of Pacific Niñas (Niños) the following winter, but it is unclear how well climate models capture this teleconnection and its role in defining the seasonal predictive skill of ENSO. Here we use an ensemble of seasonal forecast systems to demonstrate that a better representation of equatorial Atlantic variability in summer and its lagged teleconnection mechanism with the Pacific relates to enhanced predictive capacity of autumn/winter ENSO. An additional sensitivity study further shows that correcting SST variability in equatorial Atlantic improves different aspects of forecast skill in the Tropical Pacific, boosting ENSO skill. This study thus emphasizes that new efforts to improve the representation of equatorial Atlantic variability, a region with long standing systematic model biases, can foster predictive skill in the region, the Tropical Pacific and beyond, through the global impacts of ENSO.Item The stationarity of the ENSO teleconnection in european summer rainfall(Climate dynamics, 2022) Martija-Díez, Maialen; López-Parages, Jorge; Rodríguez De Fonseca, María Belén; Losada Doval, TeresaEl Niño-Southern Oscillation (ENSO) influence on European precipitation (Pcp) has been deeply analyzed. Most of the previous studies focus on the atmospheric response in wintertime during the peak of the ENSO episode, showing boreal summer a season with a marginal ENSO signal. Furthermore, the stationarity of the ENSO teleconnection with Europe has not been considered in many works, which could mask possible nonstationary impacts in other seasons like summer. In this research we find a strong influence of eastern Pacific-like ENSO on the leading variability mode of European summer Pcp, showing a dipole-like configuration and linking El Niño with drier(wetter) conditions in northern(southern) Europe. This relationship is not limited to the total cumulative Pcp, but also to the low and extreme Pcp. This impact on European rainfall is found from the 1960s to the 1990s, a 30 years-long period when the position of the extratropical northern jet stream, which acts as a waveguide, favors the teleconnection pathway to Europe. Strikingly, the ENSO events behind this teleconnection reach their peak in summer. However, we show that the resultant Pcp in Europe also depend on the ENSO characteristic of the previous seasons, which could be used for predictability purposes.Item Ocean dynamics shapes the structure and timing of Atlantic Equatorial Modes(Journal of geophysical research-oceans, 2019) Martín Rey, Marta; Polo Sánchez, Irene; Rodríguez De Fonseca, María Belén; Lazar, Alban; Losada Doval, TeresaA recent study has brought to light the co‐existence of two distinct Atlantic Equatorial Modes during negative phases of the Atlantic Multidecadal Variability: the Atlantic Niño and Horse‐Shoe (HS) mode. Nevertheless, the associated air‐sea interactions for HS mode have not been explored so far and the prevailing dynamic view of the Atlantic Niño has been questioned. Here, using a forced ocean model simulation, we find that for both modes, ocean dynamics is essential to explain the equatorial SST variations, while air‐sea fluxes control the off‐equatorial SST anomalies. Moreover, we demonstrate the key role played by ocean waves in shaping their distinct structure and timing. For the positive phase of both Atlantic Niño and HS, anomalous westerly winds trigger a set of equatorial downwelling Kelvin waves (KW) during spring‐summer. These dKWs deepen the thermocline, favouring the equatorial warming through vertical diffusion and horizontal advection. Remarkably, for the HS, an anomalous north‐equatorial wind stress curl excites an upwelling Rossby wave (RW), which propagates westward and is reflected at the western boundary becoming an equatorial upwelling KW. The uKW propagates to the east, activating the thermocline feedbacks responsible to cool the sea surface during summer months. This RW‐reflected mechanism acts as a negative feedback causing the early termination of the HS mode. Our results provide an improvement in the understanding of the TAV modes and emphasize the importance of ocean wave activity to modulate the equatorial SST variability. These findings could be very useful to improve the prediction of the Equatorial Modes.Item Skillful prediction of tropical Pacific fisheries provided by Atlantic Niños(Environmental research letters, 2021) Gómara Cardalliaguet, Íñigo; Rodríguez De Fonseca, María Belén; Mohino Harris, Elsa; Losada Doval, Teresa; Polo Sánchez, Irene; Coll, MartaTropical Pacific upwelling-dependent ecosystems are the most productive and variable worldwide, mainly due to the influence of El Niño Southern Oscillation (ENSO). ENSO can be forecasted seasons ahead thanks to assorted climate precursors (local-Pacific processes, pantropical interactions). However, due to observational data scarcity, little is known about the importance of these precursors for marine ecosystem prediction. Previous studies based on Earth System Model simulations forced by observed climate have shown that multiyear predictability of tropical Pacific marine primary productivity is possible. With recently released global marine ecosystem simulations forced by historical climate, full examination of tropical Pacific ecosystem predictability is now feasible. By complementing historical fishing records with marine ecosystem model data, we show herein that equatorial Atlantic sea surface temperatures (SSTs) constitute a valuable predictability source for tropical Pacific fisheries, which can be forecasted over large-scale areas up to three years in advance. A detailed physical-biological mechanism is proposed whereby equatorial Atlantic SSTs influence upwelling of nutrient-rich waters in the tropical Pacific, leading to a bottom-up propagation of the climate-related signal across the marine food web. Our results represent historical and near-future climate conditions and provide a useful springboard for implementing a marine ecosystem prediction system in the tropical Pacific.Item Revisiting the CMIP5 Thermocline in the Equatorial Pacific and Atlantic Oceans(Geophysical Research Letters, 2018) Castaño Tierno, Antonio; Mohino Harris, Elsa; Rodríguez De Fonseca, María Belén; Losada Doval, TeresaThe thermocline is defined as the ocean layer for which the vertical thermal gradient is maximum. In the equatorial ocean, observations led to the use of the 20 °C isotherm depth (z20) as an estimate of the thermocline. This study compares z20 against the physical thermocline in the equatorial Atlantic and Pacific Oceans, using Simple Ocean Data Assimilation reanalysis and fifth phase of the Coupled Model Intercomparison Project preindustrial control simulations. Our results show that z20 is systematically deeper and flatter than the thermocline and does not respond correctly to surface wind stress variations. It is also shown that the annual cycle of z20 is much weaker than that of the physical thermocline. This happens in both equatorial basins and indicates that z20 does not react to the same mechanisms as the thermocline. This could have important consequences in the assessment of air-sea coupling in current general circulation models and bias reduction strategies.Item Southern hemisphere circulation anomalies and impacts over subtropical South America due to different El Niño flavours(International journal of climatology, 2020) Martín Gómez, Verónica; Barreiro, Marcelo; Losada Doval, Teresa; Rodríguez De Fonseca, María BelénENSO exhibits different flavors with worldwide impacts. However, the associated teleconnections with subtropical South America (SSA) are still controversial and modelling studies are needed. Here, we analyze the Southern Hemisphere (SH) circulation anomalies and the impacts over SSA during the austral summer due to different El Niño patterns (Canonical and El Niño Modoki). The analysis is performed considering reanalysis data and two different Atmospheric General Circulation Models (SPEEDY and UCLA - AGCM). Results from reanalysis show that positive precipitation anomalies develop over SSA during Canonical El Niño events. These anomalies are induced through an increase of upper level cyclonic vorticity advection and a stronger low-level southward moisture transport. However, in El Niño Modoki events, rainfall anomalies are observed over SSA only for the strongest events. Both models are able to reproduce the precipitation signal over SSA in the Canonical El Niño case, although the underlying physical mechanism depends on the model. In SPEEDY, the increased rainfall is due to an increase of the moisture transport toward SSA, while in UCLA - AGCM it is related to both, an increase of the low-level moisture transport toward SSA and the increase of upper level cyclonic vorticity advection. The precipitation signal associated with El Niño Modoki is more controversial. While UCLA - AGCM suggests a rainfall increase over SSA, SPEEDY, in agreement with observations, does not show any statistically significant signal. However, the upper level circulation anomalies reproduced by UCLA – AGCM are more consistent with reanalysis than those from SPEEDY, which makes UCLA – AGCM to be more reliable. This result suggests increased rainfall over SSA during El Niño Modoki.Item The tropical Atlantic observing system(Frontiers in Marine Science, 2019) Rodríguez De Fonseca, María Belén; Polo Sánchez, Irene; Losada Doval, Teresa; Mohino Harris, Elsa; López Parages, JorgeThe tropical Atlantic is home to multiple coupled climate variations covering a wide range of timescales and impacting societally relevant phenomena such as continental rainfall, Atlantic hurricane activity, oceanic biological productivity, and atmospheric circulation in the equatorial Pacific. The tropical Atlantic also connects the southern and northern branches of the Atlantic meridional overturning circulation and receives freshwater input from some of the world’s largest rivers. To address these diverse, unique, and interconnected research challenges, a rich network of ocean observations has developed, building on the backbone of the Prediction and Research Moored Array in the Tropical Atlantic (PIRATA). This network has evolved naturally over time and out of necessity in order to address the most important outstanding scientific questions and to improve predictions of tropical Atlantic severe weather and global climate variability and change. The tropical Atlantic observing system is motivated by goals to understand and better predict phenomena such as tropical Atlantic interannual to decadal variability and climate change; multidecadal variability and its links to the meridional overturning circulation; air-sea fluxes of CO2 and their implications for the fate of anthropogenic CO2; the Amazon River plume and its interactions with biogeochemistry, vertical mixing, and hurricanes; the highly productive eastern boundary and equatorial upwelling systems; and oceanic oxygen minimum zones, their impacts on biogeochemical cycles and marine ecosystems, and their feedbacks to climate. Past success of the tropical Atlantic observing system is the result of an international commitment to sustained observations and scientific cooperation, a willingness to evolve with changing research and monitoring needs, and a desire to share data openly with the scientific community and operational centers. The observing system must continue to evolve in order to meet an expanding set of research priorities and operational challenges. This paper discusses the tropical Atlantic observing system, including emerging scientific questions that demand sustained ocean observations, the potential for further integration of the observing system, and the requirements for sustaining and enhancing the tropical Atlantic observing system.