Person: González Alemán, Juan Jesús
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First Name
Juan Jesús
Last Name
González Alemán
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Física de la Tierra y Astrofísica
Area
Física de la Tierra
Identifiers
4 results
Search Results
Now showing 1 - 4 of 4
Item Major role of marine heatwave and anthropogenic climate change on a giant hail event in Spain(Geophysical Research Letters, 2024) Martín, M.L.; Calvo-Sancho, Carlos; Taszarek, M.; González Alemán, Juan Jesús; Montoro-Mendoza, Ana; Díaz Fernández, Javier; Bolgiani, Pedro Mariano; Sastre Marugán, Mariano; Martín, YagoA severe hailstorm that occurred in Spain on 30 August 2022, caused material and human damage, including one fatality due to giant hailstones up to 12 cm in diameter. By applying a pseudo‐global warming approach, here we evaluate how a simultaneous marine heatwave (and anthropogenic climate change) affected a unique environment conductive to such giant hailstones. The main results show that the supercell development was influenced by an unprecedented amount of convective available energy, with significant contributions from thermodynamic factors. Numerical simulations where the marine heatwave is not present show a notable reduction in the hail‐favorable environments, related mainly to modifications in thermodynamic environment. Our simulations also indicate that the environment in a preindustrial‐like climate would be less favorable for convective hazards and thus the hailstorm event would likely not have been as severe as the observed one, being possible to perform a novel attribution of such kind.Item Horizontal kinetic energy analysis of tropical transition simulations with the WRF and HARMONIE-AROME models(Quarterly Journal of the Royal Meteorological Society, 2023) Calvo Sancho, Carlos; Bolgiani, Pedro Mariano; Subías, Álvaro; Sastre Marugán, Mariano; González Alemán, Juan Jesús; Martín, M.L.Four tropical transition (TT) events in the North Atlantic basin are simulated with the Weather Research and Forecasting (WRF) and the HARMONIE-AROME (HAR) models to study the main features of the horizontal kinetic energy (HKE) spectra of these kinds of high-energetic atmospheric system. Though most of the times similar results are obtained with both models, HAR shows a more intense filtering and numerical dissipation, whereas WRF tends to represent overenergized spectra in the synoptic scale and especially at smaller wavelengths. Predictability is dissimilar for the four TTs studied due to the different spectral curve slope obtained for each case, ranging from unlimited to very poor predictability at synoptic scale. Additionally, an increased HKE is presented in the middle–upper troposphere spectra. A deep analysis of the different terms involved in the equation of the spectral energy budget is presented through a detailed study of one of these TTs. The role of all of them is studied, connecting the energy spectra and the meteorological processes involved. The energy budget terms related to the nonlinear spectral transfer, the three-dimensional divergence, and diabatic process tendencies are identified as the key ones, whereas the potential and kinetic conversion terms and the vertical flux HKE and pressure divergence terms play a secondary role on modulating the spectrum behaviour. The major energetic contributions are found at the synoptic scale, but results show that a two-dimensional energy cascade does not fully capture the whole spectrum of a TT. The role of convection, latent heat release, and moist convection outbursts is sketched and a link within different vertical levels is found. Results show that a high-energetic system, such as a TT, can effectively alter the atmospheric energy behaviour.Item Supercell convective environments in Spain based on ERA5: hail and non-hail differences(Weather and Climate Dynamics, 2022) Calvo Sancho, Carlos; Díaz Fernández, Javier; Martín, Yago; Bolgiani, Pedro Mariano; Sastre Marugán, Mariano; González Alemán, Juan Jesús; Santos Muñoz, Daniel; Farrán, José Ignacio; Martín, M.L.Severe convective storms, in particular supercells, are occasionally responsible for a large number of property losses and damage in Spain. This paper aims to study the synoptic configurations and pre-convective environments in a dataset of 262 supercells during 2011–2020 in Spain. The events are grouped into supercells with hail (diameter larger than 5 cm) and without hail and the results are compared. ERA5 reanalysis is used to study the synoptic configurations and proximity atmospheric profiles related to the supercell events at the initial time. In addition, temperature, convective available potential energy, convective inhibition, lifting condensation level, level of free convection, height of freezing level, wind shear and storm-relative helicity are obtained for each event. Results show that supercells are more frequent on the Mediterranean coast during the warm season. Some of the variables analyzed present statistically significant differences between hail and non-hail events. In particular, supercells with hail are characterized by higher median values of most-unstable convective available potential energy than supercells without hail.Item 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, BlancaSeveral 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 Niña conditions in the tropical Pacific and upstream North Atlantic cyclones play an important role as a trigger for these events. Ensuing two-way tropospheric-stratospheric coupling and eddy feedbacks provide extended-range persistence for negative NAO conditions. These results may help improve the prediction of such exceptional events.