Subtropical cyclone formation via warm seclusion development: the importance of surface fluxes

Subtropical cyclones (STCs) are characterized by a thermal hybrid structure with tropical and extratropical features. STCs are considered a numerical modeling challenge because of their rapid intensification. A fundamental part of their strength is derived from diabatic processes associated with convection and heat fluxes from the ocean. This study evaluates the importance of surface turbulent heat fluxes during the transition of an extratropical precursor into a STC. This cyclone evolved embedded within a strong meridional flow, having a Shapiro‐Keyser structure and undergoing a warm seclusion process. To assess the importance of those heat fluxes, two Weather Research and Forecasting simulations were defined considering the presence and absence of those fluxes. Results of both simulations reveal a warm seclusion process, which weakened in absence of the heat fluxes. During the system genesis and in absence of heat fluxes, the wind and rainfall values were increased due to the remarkably intense area of frontogenesis to the northwest. Given these results and the lack of transition in the absence of heat fluxes, the frontal nature of the system was verified. Considering the heat fluxes, the obtained potential vorticity values diminished, reducing wind shear and intensifying convection in the system, which favored its transition into an STC. This study is groundbreaking in that no STC has been linked to a warm seclusion process in the Eastern North Atlantic. Additionally, simulated wind field shows an underestimation in comparison with Atmospheric Motion Vectors, used as observational data so as to give a weight to the wind analysis.This work was partially supported by research projects PCIN-2014-013-C07-04, PCIN2016-080 (UE ERA-NET Plus NEWA Project), CGL2016-78702-C2-1-R, CGL2016-78702-C2-2-R, and CGL2016-81828-REDT and the ECMWF special projects (SPESMART and SPESVALE)

Clasificación y análisis sinóptico de los ciclones subtropicales en el Atlántico nordeste

Ponencia presentada en: IX Congreso de la Asociación Española de Climatología celebrado en Almería entre el 28 y el 30 de octubre de 2014.[ES]Este trabajo analiza sinópticamente, con una base climatológica, los ciclones subtropicales (STCs) que se desarrollan en la cuenca este del Atlántico Norte, con el objetivo de complementar otros estudios sobre éstos en el Atlántico Norte, y además, mejorar su predicción. Mediante la aplicación de una serie de criterios procedentes de dos bases de datos se han identificado 15 casos de STC durante el periodo de 1979-2011.[EN]This survey analyzes subtropical cyclones (STCs) formed within the North Atlantic eastern basin from a synoptic point of view, on a climatological basis, with the main aims of complementing other studies of these storms in the North Atlantic, and aiding the forecasting community. 15 cases of STCs were identified during the period of 1979-2011 by applying a set of criteria from two databases.Este trabajo ha sido realizado gracias al proyecto CGL2011-25327 (MINECO)

¿Cómo detectar un ciclón subtropical?

Ponencia presentada en: XXXIII Jornadas Científicas de la AME y el XIV Encuentro Hispano Luso de Meteorología celebrado en Oviedo, del 7 al 9 de abril de 2014.Este trabajo ha sido realizado gracias al proyecto de investigación CGL2011-25327 (MINECO)

Evolución futura de los ciclones con características tropicales en la cuenca mediterránea: efectos de utilizar modelos de alta resolución o con acoplamiento atmósfera-océano [XXXV Jornadas AME]

Ponencia presentada en: XXXV Jornadas Científicas de la AME y el XIX Encuentro Hispano Luso de Meteorología celebrado en León, del 5 al 7 de marzo de 2018.Los ciclones con características tropicales son poco frecuentes en la Cuenca Mediterránea debido a que las condiciones atmosféricas y oceánicas son poco favorables para su desarrollo y mantenimiento. En el Mar Mediterráneo, este tipo de ciclones son llamados medicanes (“Mediterranean Hurricanes”). En los últimos años, se han observado medicanes con una fuerte intensidad como el ocurrido en Noviembre de 2011 (Miglietta et al., 2013). Los medicanes están asociados a fenómenos extremos como son fuertes vientos, precipitaciones torrenciales y fuerte oleaje, afectando sobre todo a zonas costeras. El motivo principal para realizar este trabajo es el estudio de las proyecciones de futuro para este tipo de ciclones en la Cuenca Mediterránea mediante la utilización de modelos regionales de clima, analizando los efectos del acoplamiento océano-atmósfera y la alta resolución

Evolución futura de los ciclones con características tropicales en la cuenca mediterránea: efectos de utilizar modelos de alta resolución o con acoplamiento atmósfera-océano

Ponencia presentada en: XI Congreso de la Asociación Española de Climatología celebrado en Cartagena entre el 17 y el 19 de octubre de 2018.[ES]Los ciclones con características tropicales son poco frecuentes en la Cuenca Mediterránea debido a que las condiciones atmosféricas y oceánicas son poco favorables para su desarrollo y mantenimiento. En el Mar Mediterráneo, este tipo de ciclones son llamados Medicanes (“Mediterranean Hurricanes”). El motivo principal para realizar este trabajo es el estudio de las proyecciones de futuro para este tipo de ciclones en la Cuenca Mediterránea mediante la utilización de modelos regionales de clima, analizando los efectos del acoplamiento océano-atmósfera y la alta resolución. El análisis ha sido realizado para el escenario de Clima Futuro RCP85 hasta 2100. Las simulaciones fueron hechas en el marco de trabajo de los programas europeos MedCORDEX y EuroCORDEX. El análisis de detección de Medicanes incluye el método de Picornell, (Picornell et al., 2001) para la detección de ciclones, adaptado a la detección de ciclones mesoescalares, y el empleo del metódo de Hart (Hart., 2003) para detectar ciclones que presenten estructura y características tropicales. Los primeros resultados obtenidos para dicho estudio, muestran una gran frecuencia e intensidad de Medicanes en modelos de alta resolución, en consonancia con resultados anteriores (Akhtar et al 2014). Al comparar los modelos acoplados y los no acoplados se detecta que en ambos se observa un descenso futuro del número de Medicanes, así como una intensidad mayor de éstos a finales del periodo de estudio, es decir se observan medicanes con características tropicales más marcadas y velocidades máximas de viento más altas.[EN]Cyclones with tropical characteristics are rare in the Mediterranean Sea, because atmospheric and oceanic conditions are unfavourable for their development and maintenance. In the Mediterranean Sea, this type of cyclones are called Medicanes (“Mediterranean Hurricanes”). The main aim of this work is the study of future projections for these type of cyclones in the Mediterranean basin with climate regional models, analysing the effect of the atmosphere-ocean coupling and high resolution. The analysis is realized for the future climate scenario RCP85 until 2100. The simulations were done in the framework of European projects MedCORDEX y EuroCORDEX. The analysis procedure includes the detection of cyclones with a method adapted for mesoscale cyclones (Picornell et al., 2001) and the application of Hart method (Hart, 2003) for analysing the structure of the cyclones and detecting tropical characteristic. The first results of this study show a greater frequency and intensity ofMedicanes in higher resolution models compared to lower resolution ones, in agreement with previous results (Akhtar et al 2014). The comparison of an air-sea coupled simulation with an uncoupled simulation shows interesting results: for present climate conditions, a higher medicane frequency is found in the uncoupled simulation, but during the last decades of present century more medicanes are detected in the coupled run. The projected future medicane decrease is therefore much smaller in the coupled run, pointing to complex and time-varying effects of air-sea coupling on this type of extreme phenomena

Impact of ocean–atmosphere coupling on future projection of Medicanes in the Mediterranean sea

Cyclones with tropical characteristics called medicanes (“Mediterranean Hur-ricanes”) eventually develop in the Mediterranean Sea. They have large harm-ful potential and a correct simulation of their evolution in climate projections is important for an adequate adaptation to climate change. Different studies suggest that ocean–atmosphere coupled models provide a better representation of medicanes, especially in terms of intensity and frequency. In this work, we use the regionally-coupled model ROM to study how air-sea interactions affect the evolution of medicanes in future climate projections. We find that under the RCP8.5 scenario our climate simulations show an overall frequency decrease which is more pronounced in the coupled than in the uncoupled con-figuration, whereas the intensity displays a different behaviour depending on the coupling. In the coupled run, the relative frequency of higher-intensity medicanes increases, but this is not found in the uncoupled simulation. Also, this study indicates that the coupled model simulates better the summer mini-mum in the occurrence of medicanes, avoiding the reproduction of unrealisti-cally intense events that can be found in summer in the uncoupled model

Detección de un ciclón subtropical

En este trabajo se analiza el ciclo de vida de lo que debería haber sido una típica borrasca de invierno que suele afectar a la cuenca atlántica nororiental. Sin embargo, dicha baja comenzó a adquirir características tropicales, lo que le lleva a ser identificada como ciclón subtropical. Con esta descripción se detalla una metodología para identificar este tipo de fenómenos. En ella se utilizan una serie de herramientas y campos meteorológicos que demuestran ser útiles para realzar las características de los ciclones subtropicales. Estos fenómenos han cobrado importancia durante los últimos años y han centrado la atención de la comunidad científica por llevar asociados fenómenos meteorológicos extremos de gran impacto en la sociedad y por su potencial para convertirse en tormentas tropicales o huracanes. Uno de los problemas a los que se enfrenta un meteorólogo o predictor operativo en nuestra cuenca, es el de diferenciar este tipo de ciclones con los ciclones extratropicales o típicas borrascas de invierno.Este trabajo ha sido realizado gracias al proyecto de investigación CGL2011-25327 del MINECO

Using radio astronomical receivers for molecular spectroscopic characterization in astrochemical laboratory simulations: A proof of concept

We present a proof of concept on the coupling of radio astronomical receivers and spectrometers with chemical reactorsand the performances of the resulting setup for spectroscopy and chemical simulations in laboratory astrophysics. Several experiments including cold plasma generation and UV photochemistry were performed in a 40\,cm long gas cell placed in the beam path of the Aries 40\,m radio telescope receivers operating in the 41-49 GHz frequency range interfaced with fast Fourier transform spectrometers providing 2 GHz bandwidth and 38 kHz resolution. The impedance matching of the cell windows has been studied using different materials. The choice of the material and its thickness was critical to obtain a sensitivity identical to that of standard radio astronomical observations. Spectroscopic signals arising from very low partial pressures of CH3OH, CH3CH2OH, HCOOH, OCS,CS, SO2 (<1E-03 mbar) were detected in a few seconds. Fast data acquisition was achieved allowing for kinetic measurements in fragmentation experiments using electron impact or UV irradiation. Time evolution of chemical reactions involving OCS, O2 and CS2 was also observed demonstrating that reactive species, such as CS, can be maintained with high abundance in the gas phase during these experiments.Comment: Accepted for publication in Astronomy and Astrophysics in September 21, 2017. 16 pages, 18 figure

Modelización regional del proyecto escena de ciclones subtropicales sobre el Atlántico nororiental

Ponencia presentada en: XXXIV Jornadas Científicas de la AME y el XVII Encuentro Hispano Luso de Meteorología celebrado en Teruel, del 29 de febrero al 2 de marzo de 2016

Subtropical cyclones projections in future climate conditions over the northeastern Atlantic

Ponencia presentada en: XXXV Jornadas Científicas de la AME y el XIX Encuentro Hispano Luso de Meteorología celebrado en León, del 5 al 7 de marzo de 2018.Hybrid cyclones called subtropical cyclones (STCs) have attracted the attention of scientific and forecasting community due to their identification as damaging weather systems. A study of STCs under future climate scenarios has not been performed yet. For the first time, in this work we analyse the capability of regional climate models (RCMs) to simulate STCs in addition to searching for possible alterations in their frequency and intensity due to anthropogenic climate change over the subtropical northeastern Atlantic basin. By using an ensemble of three RCMs nested in four different global climate models (GCMs), we find that RCMs acceptably reproduce STCs (except for certain model combinations) for the historical climate period (1951–2000). For future climate conditions under A1B, A2 and B1 scenarios (2001–2050), more simulations indicate a decrease in the frequency of STCs than those which find an increase. This decrease is showed to be partially due to a reduced presence of extratropical cyclones, from which they tend to form, within that region. However, no strong agreement between simulations has been obtained, and other factors like the changes in the conversion rate could affect STCs in the future. With respect to intensity, no clear tendency is found