Person:
González Alemán, Juan Jesús

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First Name
Juan Jesús
Last Name
González Alemán
URI
https://hdl.handle.net/20.500.14352/87048
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Física de la Tierra y Astrofísica
Area
Física de la Tierra
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2022 - 20232
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Subject: 550.3 ×

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    Abrupt and persistent atmospheric circulation changes in the North Atlantic under La Niña conditions
    (Weather and Climate Extremes, 2023) García-Burgos, Marina; Gómara Cardalliaguet, Íñigo; Rodríguez De Fonseca, María Belén; González Alemán, Juan Jesús; Zurita Gotor, Pablo; Ayarzagüena Porras, Blanca
    Several recent studies have linked the exceptional North Atlantic and Eurasian atmospheric evolution during late February and March 2018 to the Sudden Stratospheric Warming (SSW) that took place a few weeks earlier. February 2018 was characterized by an abrupt transition from the positive to the negative phase of the North Atlantic Oscillation (NAO) and a subsequent persistence of the negative NAO for several weeks. This paper investigates the contribution of atmospheric and oceanic phenomena to both the 2018 event and a set of 19 identified analogues (including the former) for the period 1959-2022. Evidence is given that La Nin similar to a conditions in the tropical Pacific and upstream North Atlantic cyclones play an important role as a trigger for these events. Ensuing two-way tropospheric-strato-spheric coupling and eddy feedbacks provide extended-range persistence for negative NAO conditions. These results may help improve the prediction of such exceptional events.
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    Wind kinetic energy climatology and effective resolution for the ERA5 reanalysis
    (Climate dynamics, 2022) Bolgiani, Pedro; Calvo Sancho, C.; Díaz Fernández, Javier; Quitián Hernández, Lara; Santos Muñoz, D.; Farrán, J. I.; González Alemán, Juan Jesús; Valero Rodríguez, Francisco; Martín, M. L.; Sastre Marugán, Mariano
    ERA5 represents the state of the art for atmospheric reanalyses and is widely used in meteorological and climatological research. In this work, this dataset is evaluated using the wind kinetic energy spectrum. Seasonal climatologies are generated for 30 degrees latitudinal bands in the Northern Hemisphere (periodic domain) and over the North Atlantic area (limited-area domain). The spectra are also assessed to determine the effective resolution of the reanalysis. The results present notable differences between the latitudinal domains, indicating that ERA5 is properly capturing the synoptic conditions. The seasonal variability is adequate too, being winter the most energetic, and summer the least energetic season. The limited area domain results introduce a larger energy density and range. Despite the good results for the synoptic scales, the reanalysis' spectra are not able to properly reproduce the dissipation rates at mesoscale. This is a source of uncertainties which needs to be taken into account when using the dataset. Finally, a cyclone tropical transition is presented as a case study. The spectrum generated shows a clear difference in energy density at every wavelength, as expected for a highly-energetic status of the atmosphere.