Person: Yagüe Anguis, Carlos
Universidad Complutense de Madrid
Faculty / Institute
Física de la Tierra y Astrofísica
Física de la Tierra
Now showing 1 - 10 of 19
PublicationThe BLLAST field experiment: Boundary-Layer late afternoon and sunset turbulence(European Geosciences Union, 2014-10-16) Yagüe Anguis, Carlos; Román Cascón, Carlos; Sastre Marugán, MarianoDue to the major role of the sun in heating the earth's surface, the atmospheric planetary boundary layer over land is inherently marked by a diurnal cycle. The afternoon transition, the period of the day that connects the daytime dry convective boundary layer to the night-time stable boundary layer, still has a number of unanswered scientific questions. This phase of the diurnal cycle is challenging from both modelling and observational perspectives: it is transitory, most of the forcings are small or null and the turbulence regime changes from fully convective, close to homogeneous and isotropic, toward a more heterogeneous and intermittent state. These issues motivated the BLLAST (Boundary-Layer Late Afternoon and Sunset Turbulence) field campaign that was conducted from 14 June to 8 July 2011 in southern France, in an area of complex and heterogeneous terrain. A wide range of instrumented platforms including full-size aircraft, remotely piloted aircraft systems, remote-sensing instruments, radiosoundings, tethered balloons, surface flux stations and various meteorological towers were deployed over different surface types. The boundary layer, from the earth's surface to the free troposphere, was probed during the entire day, with a focus and intense observation periods that were conducted from midday until sunset. The BLLAST field campaign also provided an opportunity to test innovative measurement systems, such as new miniaturized sensors, and a new technique for frequent radiosoundings of the low troposphere. Twelve fair weather days displaying various meteorological conditions were extensively documented during the field experiment. The boundary-layer growth varied from one day to another depending on many contributions including stability, advection, subsidence, the state of the previous day's residual layer, as well as local, meso- or synoptic scale conditions. Ground-based measurements combined with tethered-balloon and airborne observations captured the turbulence decay from the surface throughout the whole boundary layer and documented the evolution of the turbulence characteristic length scales during the transition period. Closely integrated with the field experiment, numerical studies are now underway with a complete hierarchy of models to support the data interpretation and improve the model representations. PublicationCan we use satellite-based soil-moisture products at high resolution to investigate land-use differences and land-atmosphere interactions? a case study in the savanna(MDPI AG, 2020-06) Yagüe Anguis, CarlosThe use of soil moisture (SM) measurements from satellites has grown in recent years, fostering the development of new products at high resolution. This opens the possibility of using them for certain applications that were normally carried out using in situ data. We investigated this hypothesis through two main analyses using two high-resolution satellite-based soil moisture (SBSM) products that combined microwave with thermal and optical data: (1) The Disaggregation based on Physical And Theoretical scale Change (DISPATCH) and, (2) The Soil Moisture Ocean Salinity-Barcelona Expert Center (SMOS-BEC Level 4). We used these products to analyse the SM differences among pixels with contrasting vegetation. This was done through the comparison of the SM measurements from satellites and the measurements simulated with a simple antecedent precipitation index (API) model, which did not account for the surface characteristics. Subsequently, the deviation of the SM from satellite with respect to the API model (bias) was analysed and compared for contrasting land use categories. We hypothesised that the differences in the biases of the varied categories could provide information regarding the water retention capacity associated with each type of vegetation. From the satellite measurements, we determined how the SM depended on the tree cover, i.e., the denser the tree cover, the higher the SM. However, in winter periods with light rain events, the tree canopy could dampen the moistening of the soil through interception and conducted higher SM in the open areas. This evolution of the SM differences that depended on the characteristics of each season was observed both from satellite and from in situ measurements taken beneath a tree and in grass on the savanna landscape. The agreement between both types of measurements highlighted the potential of the SBSM products to investigate the SM of each type of vegetation. We found that the results were clearer for DISPATCH, whose data was not smoothed spatially as it was in SMOS-BEC. We also tested whether the relationships between SM and evapotranspiration could be investigated using satellite data. The answer to this question was also positive but required removing the unrealistic high-frequency SM oscillations from the satellite data using a low pass filter. This improved the performance scores of the products and the agreement with the results from the in situ data. These results demonstrated the possibility of using SM data from satellites to substitute ground measurements for the study of land–atmosphere interactions, which encourages efforts to improve the quality and resolution of these measurements. PublicationRadiation and cloud-base lowering fog events: observational analysis and evaluation of WRF and HARMONIE(Elsevier Science INC, 2019-11-15) Román Cascón, Carlos; Yagüe Anguis, Carlos; Steeneveld, Gert-Jan; Morales, Gema; Arrillaga Mitxelena, Jon Ander; Sastre Marugán, Mariano; Maqueda Burgos, GregorioMost of the effects caused by fog are negative for humans. Yet, numerical weather prediction (NWP) models still have problems to simulate fog properly, especially in operational forecasts. In the case of radiation fog, this is partially caused by the large sensitivity to many aspects that contribute to its formation, evolution and dissipation, such as the synoptic and local conditions, the near-surface turbulence, the aerosol and droplet microphysics, or the surface characteristics, among others. This work focuses on an interesting 8-day period with several alternating radiation and cloud-base lowering (CBL) fog events observed at the Research Centre for the Lower Atmosphere (CIBA) in the Spanish Northern Plateau. The site was appropriately instrumented to characterize fog from the surface up to the height of 100 m. On the one hand, radiation fog events are associated with strong surface cooling leading to high stability close to the surface and low values of turbulence, giving rise to shallow fog. The evolution of this type of fog is markedly sensitive to the dynamical conditions close to the surface (i.e., wind speed and turbulence). On the other hand, CBL fog presents deeper thickness associated with higher values of turbulence and less stability. Subsequently, we evaluated the fog-forecasting skill of two mesoscale models (WRF and HARMONIE) configured as similar as possible. Both models present more difficulties simulating radiation fog events than CBL ones. However, the duration and vertical extension of the CBL fog events is normally overestimated. This extended-fog avoids the surface radiative cooling needed to simulate radiation fog events formed the following nights. Therefore, these periods with alternating CBL and radiation fog are especially challenging for NWP models. PublicationFrom weak to intense downslope winds: origin, interaction with boundary-layer turbulence and impact on CO2 variability(Copernicus publications, 2019-04-08) Arrillaga Mitxelena, Jon Ander; Yagüe Anguis, Carlos; Román Cascón, Carlos; Sastre Marugán, Mariano; Jiménez, María Antonia; Maqueda Burgos, Gregorio; Vilà-Guerau de Arellano, JordiThe interconnection of local downslope flows of different intensities with the turbulent characteristics and thermal structure of the atmospheric boundary layer (ABL) is investigated through observations. Measurements are carried out in a relatively flat area 2 km away from the steep slopes of the Sierra de Guadarrama (central Iberian Peninsula). A total of 40 thermally driven downslope events are selected from an observational database spanning the summer 2017 period by using an objective and systematic algorithm that accounts for a weak synoptic forcing and local downslope wind direction. We subsequently classify the downslope events into weak, moderate and intense categories, according to their maximum 6 m wind speed. This classification enables us to contrast their main differences regarding the driving mechanisms, associated ABL turbulence and thermal structure, and the major dynamical characteristics. We find that the strongest downslope flows (U > 3.5 m s^(−1) ) develop when soil moisture is low (< 0.07 m3 m^(−3) ) and the synoptic wind not so weak (3.5 m s^(−1) < V_(850) < 6 m s^(−1) ) and roughly parallel to the direction of the downslope flow. The latter adds an important dynamical input, which induces an early flow advection from the nearby steep slope, when the local thermal profile is not stable yet. Consequently, turbulence driven by the bulk shear increases up to friction velocity (u∗) ≃ 1 m s^(−1), preventing the development of the surfacebased thermal inversion and giving rise to the so-called weakly stable boundary layer. On the contrary, when the dynamical input is absent, buoyancy acceleration drives the formation of a katabatic flow, which is weak (U < 1.5 m s^(−1)) and generally manifested in the form of a shallow jet below 3 m. The relative flatness of the area favours the formation of very stable boundary layers marked by very weak turbulence (u∗ < 0.1 m s^(−1)). In between, moderate downslope flows show intermediate characteristics, depending on the strength of the dynamical input and the occasional interaction with down-basin winds. On the other hand, by inspecting individual weak and intense events, we further explore the impact of downslope flows on CO2 variability. By relating the dynamics of the distinct turbulent regimes to the CO2 budget, we are able to estimate the contribution of the different terms. For the intense event, indeed, we infer a horizontal transport of 67 ppm in 3 h driven by the strong downslope advection. PublicationClimatology of precipitation over the Iberian Central System mountain range(John WiIley & Sons LTD, 2013-07) Durán Montejano, Luis; Sánchez, E.; Yagüe Anguis, CarlosAn analysis of the observed precipitation for the last 22 years (1989–2010) over Sierra de Guadarrama (centre of Iberian Central System) has been performed. Since this area has received less attention compared with other mountain ranges in Europe and the rest of the world, an exhaustive compilation of literature on precipitation main characteristics on Central Iberia (SW Europe) has been done. The analysis, based on both rain gauges and reanalysis, is focused on the search of the atmospheric mechanisms and moisture sources that lead to precipitation. Also, emphasis has been made in the role played by orography conditioning, the complex spatial patterns observed in the region. This work shows how it behaves as an orographic island that rises over an extensive plateau with a marked Atlantic forcing despite the distance these masses have to travel inlands, with mostly of wet days due to advection of moisture from the ocean and small amount of rain due to local sources of humidity and convective precipitation. It also shows the great enhancement of precipitation caused by the range due to orographic precipitation and the big differences found at the downwind and upwind side of the mountain leading to marked spatial patterns seasonal dependent, complex vertical gradients and high wind direction dependency. Finally, statistically significant mean conditions of variables related with orographic precipitation are given in order to be used as boundary conditions for orographic precipitation modelling exercises. This works gives a climatic framework for future precipitation assessments that could be conducted combining measurements and such models. PublicationImpacts of afternoon and evening sea-breeze fronts on local turbulence, and on CO2 and radon-222 transport(Wiley, 2018-08-06) Arrillaga Mitxelena, Jon Ander; Vilà-Guerau de Arellano, Jordi; Bosveld, Fred; Klein Baltink, Henk; Yagüe Anguis, Carlos; Sastre Marugan, Mariano; Román-Cascón, CarlosWe investigated sharp disruptions of local turbulence and scalar transport due to the arrival of sea-breeze fronts (SBFs). To this end, we employed a comprehensive 10-year observational database from the Cabauw Experimental Site for Atmospheric Research (CESAR, the Netherlands). Sea-breeze (SB) days were selected using a five-filter algorithm, which accounts for large-scale conditions and a clear mesoscale-frontal signal associated with the land-sea contrast. Among those days (102 in all, 8.3%), based on the value of the sensible-heat flux at the onset of SB, we identified three atmospheric boundary-layer (ABL) regimes: convective, transition and stable. In the convective regime, the thermally driven convective boundary layer is only slightly altered by a small enhancement of the shear when the SBF arrives. Regarding the transition regime, we found that the ABL afternoon transition is accelerated. This was quantified by estimating the contributions of shear and buoyancy to the turbulent kinetic energy. Other relevant disruptions are the sharp reduction in ABL depth (similar to 250 m/hr) and the sudden increase in average wind speed (> 2 m/s). In the stable regime, the arrival of the SB leads to disturbances in the wind profile at the surface layer. We observed a deviation of more than 1 m/s in the observed surface-layer wind profile compared with the profile calculated using Monin-Obukhov Similarity Theory (MOST). Our findings furthermore reveal the determinant role of the SB direction in the transport of water vapour, CO2 and Rn-222. The return of continental air masses driven by the SB circulation generates sharp CO2 increases (up to 14 ppm in half an hour) in a few SB events. We suggest that the variability in Rn-222 evolution may also be influenced by other non-local processes such as the large-scale footprint from more remote sources. PublicationMeteolab como herramienta educativa de Meteorología en el Aula(2021-10) Rodriguez Fonseca, María Belén; Abalos Álvarez, Marta; Alvarez Solas, Jorge; Ayarzagüena Porras, Blanca; Benito Barca, Samuel; Calvo Fernández, Natalia; de la Cámara Illescas, Alvaro; Durán Montejano, Luis; García Herrena, Ricardo; Garrido Pérez, José Manuel; Gómara Cardalliaguet, Iñigo; Losada Doval, Teresa; Mohino Harris, Elsa; Montoya Redondo, Marisa Luisa; Ordoñez García, Carlos; Polo Sánchez, Irene; Robinson, Alexander James; Sastre Marugán, Mariano; Serrano Mendoza, Encarnación; Yagüe Anguis, Carlos; Zurita Gotor, Pablo; García Burgos, Marina; González Alemán, Juan Jesús; González Barras, Rosa María; González Rouco, Jesús Fidel; Martín Gómez, Verónica; Maqueda Burgos, GregorioEl Presente proyecto es una continuación de proyectos anteriores dentro de la plataforma de divulgación Meteolab. Meteolab es un proyecto de divulgación de Meteorología y Clima que tiene su origen en 2002, cuando se comenzaron a diseñar experimentos de bajo coste con materiales caseros para la Semana de la Ciencia de la Comunidad de Madrid (CAM). Con los años, se generó un conocimiento que se materializó en 2010 con la concesión de un Proyecto de Innovación Educativa (PIE) financiado por la Universidad Complutense de Madrid (UCM), dirigido por Belén Rodríguez de Fonseca. Gracias a este primer proyecto en el que trabajaron muchos profesores y alumnos de ciencias de la atmósfera, se gestó un portal web (meteolab.fis.ucm.es) en el que los experimentos se explicaban y se grababan para impulsar su difusión. Más adelante, en un segundo proyecto de Innovación Educativa, dirigido por la profesora Maria Luisa Montoya, los contenidos fueron traducidos al inglés. En concreto, los experimentos que componen Meteolab tienen como principal objetivo entender los principios y variables que determinan el comportamiento de las masas de aire en la atmósfera y de agua en el océano. La idea consiste en visualizar con experimentos sencillos las leyes físicas que gobiernan la atmósfera y el océano: movimientos horizontales y verticales, cambios de estado, mezcla y equilibrio, así como la interacción entre componentes. Se persigue observar los procesos meteorológicos familiares, como son la formación de una nube, los tornados, la convección, la formación de borrascas o la lluvia, entendiendo los procesos físicos que los producen. Finalmente, Meteolab permite también visualizar fenómenos climáticos como el efecto invernadero, el fenómeno de El Niño, el deshielo del Ártico, la influencia de los volcanes en el clima o la subida del nivel del mar. Existe un catálogo de experimentos, la mayoría de los cuales pueden consultarse a través del portal meteolab.fis.ucm.es, encontrándose todos ellos físicamente localizados en el Laboratorio Elvira Zurita de la Facultad de Ciencias Físicas. Tras la experiencia acumulada durante los 18 años de existencia de Meteolab, en los que se han adecuado las explicaciones de los experimentos a distintos niveles de dificultad (infantil, primaria, secundaria, bachillerato y Universidad de mayores), se ha sugerido la idoneidad de adaptar los contenidos a los estudiantes del Grado en Física y del Máster en Meteorología y Geofísica de la UCM. Así, por ejemplo, cuando se explica la formación de una nube, se puede ir complicando el discurso dependiendo de los diferentes ciclos de la enseñanza. De esta manera, para un nivel de escuela primaria uno sólo tiene que explicar que el aire se enfría al ascender, y al enfriarse se forman gotas de agua que forman las nubes. Al llegar a secundaria, los estudiantes aprenden el concepto de presión atmosférica y la relación entre la temperatura, la presión y el volumen de una parcela de aire. Más adelante, en el Grado en Física, se estudia la tensión de vapor, la expansión adiabática y la existencia de núcleos de condensación. Finalmente, en el Máster en Meteorología se aprenden los distintos procesos de nucleación y tipos de nubes. Todos estos conceptos van complicando la explicación, por lo que un mismo experimento puede explicarse tanto en una escuela infantil como en una Universidad. Es por ello, que, aprovechando la plataforma de divulgación Meteolab, hemos decidido dar un paso adelante y adaptar y ampliar los contenidos de Meteolab, para así poder integrarlos en los currícula del Grado en Física y del Máster en Meteorología y Geofísica de la UCM. Con todo ello, los objetivos del presente proyecto han sido: -Implementar los experimentos de Meteolab en el Aula, tanto en las asignaturas de Grado como en las de Máster. -Adaptar los contenidos existentes del portal web Meteolab (meteolab.fis.ucm.es) a las asignaturas relacionadas con Meteorología del Grado en Física y del Máster en Meteorología y Geofísica, con el fin de visualizar procesos físicos que se explican en el aula. -Añadir a Meteolab nuevos contenidos en relación con la dinámica de la atmósfera y el cambio climático. -Evaluar la mejora de la comprensión por parte del alumnado de los procesos que tienen lugar principalmente en la atmósfera y el océano, y su relación con el clima y su variabilidad. PublicationReview of wave-turbulence interactions in the stable atmospheric boundary layer(American Geophysical Union, 2015-09) Yagüe Anguis, Carlos; otros, ...Flow in a stably stratified environment is characterized by anisotropic and intermittent turbulence and wavelike motions of varying amplitudes and periods. Understanding turbulence intermittency and wave-turbulence interactions in a stably stratified flow remains a challenging issue in geosciences including planetary atmospheres and oceans. The stable atmospheric boundary layer (SABL) commonly occurs when the ground surface is cooled by longwave radiation emission such as at night over land surfaces, or even daytime over snow and ice surfaces, and when warm air is advected over cold surfaces. Intermittent turbulence intensification in the SABL impacts human activities and weather variability, yet it cannot be generated in state-of-the-art numerical forecast models. This failure is mainly due to a lack of understanding of the physical mechanisms for seemingly random turbulence generation in a stably stratified flow, in which wave-turbulence interaction is a potential mechanism for turbulence intermittency. A workshop on wave-turbulence interactions in the SABL addressed the current understanding and challenges of wave-turbulence interactions and the role of wavelike motions in contributing to anisotropic and intermittent turbulence from the perspectives of theory, observations, and numerical parameterization. There have been a number of reviews on waves, and a few on turbulence in stably stratified flows, but not much on wave-turbulence interactions. This review focuses on the nocturnal SABL; however, the discussions here on intermittent turbulence and wave-turbulence interactions in stably stratified flows underscore important issues in stably stratified geophysical dynamics in general. PublicationPerformance evaluation of a multiscale modelling system applied to particulate matter dispersion in a real traffic hot spot in Madrid (Spain)(Turkish Natl. committee air pollution res. & control-tuncap, 2020-01) Santiago, J. L.; Sánchez, B.; Quaassdorff, C.; Paz, D. de la; Martilli, A.; Martín, F.; Borge, R.; Rivas, E.; Gómez Moreno, F.J.; Díaz, E.; Artiñano, B.; Yagüe Anguis, Carlos; Vardoulakis, S.Urban air pollution is one of the most important environmental problems nowadays. Understanding urban pollution is rather challenging due to different factors that produce a strongly heterogeneous pollutant distribution within streets. Observed concentrations depend on processes occurring at a wide range of spatial and temporal scales, complex wind flow and turbulence patterns induced by urban obstacles and irregular traffic emissions. The main objective of this paper is to model particulate matter dispersion at microscale while considering the effects of mesoscale processes. Computational Fluid Dynamic (CFD) PM10 simulations were performed taking into account high spatial resolution traffic emissions from a microscale traffic model and inlet vertical profiles of meteorological variables from Weather Research and Forecasting (WRF) model. This modelling system is evaluated by using meteorological and PM10 concentration data from intensive experimental campaigns carried out on 25th February and 6th July, 2015 in a real urban traffic hot-spot in Madrid. The effect of uncertainties in the inlet profiles from mesoscale input data on microscale results is assessed. Additionally, the importance of the sensible surface heat fluxes (SHF) provided by WRF and the selection of an appropriate turbulent Schmidt number in the dispersion equation are investigated. The main conclusion is that the modelling system accurately reproduces PM10 dispersion imposing appropriate inputs (meteorological variables and SHF) and a suitable turbulent Schmidt number. Better agreement is found for simulation with a low turbulent Schmidt number. This approach improves the standard microscale modelling alone because more realistic boundary conditions and mesoscale processes are considered. PublicationInfluence of atmospheric stratification on the integral scale and fractal dimension of turbulent flows(European Geosciences Union, 2016) Tijera Carrión, Manuel; Maqueda Burgos, Gregorio; Yagüe Anguis, CarlosIn this work the relation between integral scale and fractal dimension and the type of stratification in fully developed turbulence is analyzed. The integral scale corresponds to that in which energy from larger scales is incoming into a turbulent regime. One of the aims of this study is the understanding of the relation between the integral scale and the bulk Richardson number, which is one of the most widely used indicators of stability close to the ground in atmospheric studies. This parameter will allow us to verify the influence of the degree of stratification over the integral scale of the turbulent flows in the atmospheric boundary layer (ABL). The influence of the diurnal and night cycles on the relationship between the fractal dimension and integral scale is also analyzed. The fractal dimension of wind components is a turbulent flow characteristic, as has been shown in previous works, where its relation to stability was highlighted. Fractal dimension and integral scale of the horizontal (u′) and vertical (w′) velocity fluctuations have been calculated using the mean wind direction as a framework. The scales are obtained using sonic anemometer data from three elevations 5.8, 13 and 32 m above the ground measured during the SABLES 98 field campaign (Cuxart et al., 2000). In order to estimate the integral scales, a method that combines the normalized autocorrelation function and the best Gaussian fit (R² ≥ 0.70) has been developed. Finally, by comparing, at the same height, the scales of u′ and w′ velocity components, it is found that the turbulent flows are almost always anisotropic.