Person:
Valero Rodríguez, Francisco

First Name

Francisco

Last Name

Valero Rodríguez

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Física de la Tierra y Astrofísica

Area

Física de la Tierra

Identifiers

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Now showing 1 - 10 of 28

Surface wind regionalization in complex terrain
(American Meteorological Society, 2008-01) Jiménez, P. A.; González Rouco, J. Fidel; Montávez, J. P.; Navarro, J.; García Bustamante, E.; Valero Rodríguez, Francisco
Daily wind variability in the Comunidad Foral de Navarra in northern Spain was studied using wind observations at 35 locations to derive subregions with homogeneous temporal variability. Two different methodologies based on principal component analysis were used to regionalize: 1) cluster analysis and 2) the rotation of the selected principal components. Both methodologies produce similar results and lead to regions that are in general agreement with the topographic features of the terrain. The meridional wind variability is similar in all subregions, whereas zonal wind variability is responsible for differences between them. The spectral analysis of wind variability within each subregion reveals a dominant annual cycle and the varying presence of higher-frequency contributions in the subregions. The valley subregions tend to present more variability at high frequencies than do higher-altitude sites. Last, the influence of large-scale dynamics on regional wind variability is explored by studying connections between wind in each subregion and sea level pressure fields. The results of this work contribute to the characterization of wind variability in a complex terrain region and constitute a framework for the validation of mesoscale model wind simulations over the region.
Springtime connections between the large-scale sea-level pressure field and gust wind speed over Iberia and the Balearics
(European Geosciences Union / Copernicus Publications, 2011-01-21) Martín, V.L.; Valero Rodríguez, Francisco; Pascual Montano, Alberto; Morata, A,; Luna, M.Y.
This paper investigates, by means of Singular Value Decomposition analysis, the springtime relationships between the mean sea-level pressure field over the North Atlantic and the regional wind gusts over the Iberian Peninsula, identifying the main atmospheric circulation patterns linked to gust wind speed anomaly configurations. The statistical significance of the obtained modes is investigated by means of Monte Carlo approach. The analysis highlighted that the covariability is dominated by two main largescale features of the atmospheric circulation over the North Atlantic. The first mode relates to Iberian gust wind speeds to the Scandinavian pattern (SCAND), linking the large-scale pattern to above-normal wind gusts. The second covariability mode, associated with the North Atlantic Oscillation (NAO) pattern, correlates with maximum wind speeds over Iberia. An enhanced spring NAO pattern is related to positive (negative) wind gust correlations over northern (southern) Iberia. To find true relationships between large-scale atmospheric field and the gust wind speeds, composite maps were built up to give an average atmospheric circulation associated with coherent wind gust variability over Iberia.
Springtime connections between the large-scale sea-level pressure field and gust wind speed over Iberia and the Balearics
(European Geosciences Union, 2011) Martín, M. L.; Valero Rodríguez, Francisco; Pascual Collar, Alvaro de; Morata, A.; Luna, M. Y.
This paper investigates, by means of Singular Value Decomposition analysis, the springtime relationships between the mean sea-level pressure field over the North Atlantic and the regional wind gusts over the Iberian Peninsula, identifying the main atmospheric circulation patterns linked to gust wind speed anomaly configurations. The statistical significance of the obtained modes is investigated by means of Monte Carlo approach. The analysis highlighted that the covariability is dominated by two main large-scale features of the atmospheric circulation over the North Atlantic. The first mode relates to Iberian gust wind speeds to the Scandinavian pattern (SCAND), linking the large-scale pattern to above-normal wind gusts. The second covariability mode, associated with the North Atlantic Oscillation (NAO) pattern, correlates with maximum wind speeds over Iberia. An enhanced spring NAO pattern is related to positive (negative) wind gust correlations over northern (southern) Iberia. To find true relationships between large-scale atmospheric field and the gust wind speeds, composite maps were built up to give an average atmospheric circulation associated with coherent wind gust variability over Iberia.
Numerical Simulation of a Heavy Precipitation Event in the Vicinity of Madrid-Barajas International Airport: Sensitivity to Initial Conditions, Domain Resolution, and Microphysics Parameterizations
(MDPI, 2018-09) Bolgiani, Pedro; Fernández González, Sergio; Valero Rodríguez, Francisco; Merino, Andrés; García Ortega, Eduardo; Sánchez, José Luis; Martín, María Luisa
Deep convection is a threat to many human activities, with a great impact on aviation safety. On 7 July 2017, a widespread torrential precipitation event (associated with a cut-off low at mid-levels) was registered in the vicinity of Madrid, causing serious flight disruptions. During this type of episode, accurate short-term forecasts are key to minimizing risks to aviation. The aim of this research is to improve early warning systems by obtaining the best WRF model setup. In this paper, the aforementioned event was simulated. Various model configurations were produced using four different physics parameterizations, 3-km and 1-km domain resolutions, and 0.25 degrees and 1 degrees initial condition resolutions. Simulations were validated using data from 17 rain gauge stations. Two validation indices are proposed, accounting for the temporal behaviour of the model. Results show significant differences between microphysics parameterizations. Validation of domain resolution shows that improvement from 3 to 1 km is negligible. Interestingly, the 0.25 degrees resolution for initial conditions produced poor results compared with 1 degrees. This may be linked to a timing error, because precipitation was simulated further east than observed. The use of ensembles generated by combining different WRF model configurations produced reliable precipitation estimates.
Temperature response to changes in vegetation fraction cover in a regional climate model
(MDPI, 2021-05-05) Jiménez Gutiérrez, José Manuel; Valero Rodríguez, Francisco; Ruiz Martínez, Jesús; Montávez, Juan Pedro
Vegetation plays a key role in partitioning energy at the surface. Meteorological and Climate Models, both global and regional, implement vegetation using two parameters, the vegetation fraction and the leaf area index, obtained from satellite data. In most cases, models use average values for a given period. However, the vegetation is subject to strong inter-annual variability. In this work, the sensitivity of the near surface air temperature to changes in the vegetation is analyzed using a regional climate model (RCM) over the Iberian Peninsula. The experiments have been designed in a way that facilitates the physical interpretation of the results. Results show that the temperature sensitivity to vegetation depends on the time of year and the time of day. Minimum temperatures are always lower when vegetation is increased; this is due to the lower availability of heat in the ground due to the reduction of thermal conductivity. Regarding maximum temperatures, the role of increasing vegetation depends on the available moisture in the soil. In the case of hydric stress, the maximum temperatures increase, and otherwise decrease. In general, increasing vegetation will lead to a higher daily temperature range, since the decrease in minimum temperature is always greater than the decrease for maximum temperature. These results show the importance of having a good estimate of the vegetation parameters as well as the implications that vegetation changes due to natural or anthropogenic causes might have in regional climate for present and climate change projections.
Aircraft icing: in-cloud measurements and sensitivity to physical parameterizations
(Amer Geophysical Union, 2019-10) Merino, A.; García Ortega, E.; Fernández González, S.; Díaz Fernández, J.; Quitián Hernández, L.; Martín, M.L.; López, L.; Marcos, J.L.; Valero Rodríguez, Francisco; Sánchez, J.L.
The prediction of supercooled cloud drops in the atmosphere is a basic tool for aviation safety, owing to their contact with and instant freezing on sensitive locations of the aircraft. One of the main disadvantages for predicting atmospheric icing conditions is the acquisition of observational data. In this study, we used in‐cloud microphysics measurements taken during 10 flights of a C‐212 research aircraft under winter conditions, during which we encountered 37 regions containing supercooled liquid water. To investigate the capability of the Weather Research and Forecasting model to detect regions containing supercooled cloud drops, we propose a multiphysics ensemble approach. We used four microphysics and two planetary boundary layer schemes. The Morrison parameterization yielded superior results, whereas the planetary boundary layer schemes were essential in evaluating the presence of liquid water content. The Goddard microphysics scheme best detected the presence of ice water content but tended to underestimate liquid water content.
Characterization of the Martian Surface Layer
(American Meteorological Society, 2009-01) Martínez, Germán; Valero Rodríguez, Francisco; Vázquez Martínez, Luis
We have estimated the diurnal evolution of Monin- Obukhov length, friction velocity, temperature scale, surface heat flux, eddy-transfer coefficients for momentum and heat, and turbulent viscous dissipation rate on the Martian surface layer for a complete Sol belonging to the Pathfinder mission. All these magnitudes have been derived from in situ wind and temperature measurements at around 1.3 m height, and simulated ground temperature (from 6 a.m. Sol 25 to 6 a.m. Sol 26). Up to the moment, neither values of turbulent viscous dissipation rate and eddy-transfer coefficients from in situ measurements for the Martian surface layer, nor diurnal evolutions of all the previous mentioned turbulent parameters for the Pathfinder had been obtained. Monin-Obukhov similarity theory for stratified surface layers has been applied to obtain the results. The values assigned to the surface roughness, and the applied parameterization of the interfacial sublayer will be discussed in detail due to the sensibility of the results on them. We have found similarities concerning the order of magnitude and qualitative behaviour of Monin- Obukhov length, friction velocity and turbulent vis-cous dissipation rate on Earth and on Mars. However, magnitudes directly related to the lower Martian atmospheric density and thermal inertia, like temperature scale and hence surface heat flux, show different order of magnitude. Finally, turbulent exchanges in the first meters have been found to be just two orders of magnitude higher than the molecular ones, while on Earth around five orders of magnitude separate both mechanisms.
Natural and anthropogenic modes of surface temperature variations in the last thousand years
(American Geophysical Union, 2005-04-27) Zorita, E.; González Rouco, J. Fidel; von Storch, H.; Montávez,, J. P.; Valero Rodríguez, Francisco
The spatial patterns of surface air-temperature variations in the period 1000 to 2100, simulated with the ECHO-G atmosphere-ocean coupled model, are analyzed. The model was driven by solar, volcanic and greenhouse gas forcing. The leading mode of temperature variability in the preindustrial period represents an almost global coherent variation of temperatures, with larger amplitudes over the continents and Northern Hemisphere. This mode also describes a large part of the spatial structure of the warming simulated in the 21st century. However, in the 21st century, regional departures from this spatial structure are also present and can be ascribed to atmospheric circulation responses to anthropogenic forcing in the last decades of the 21st century.
An approach for the forecasting of wind strength tailored to routine observational daily wind gust data
(Elsevier Science Inc, 2014-02) Valero Rodríguez, Francisco; Pascual, A.; Martín, M.L.
Daily wind gusts observed over Spain have been estimated by means of the statistical downscaling analogue model ANPAF developed by the authors. The model diagnoses large-scale atmospheric circulation patterns and subsequently estimates wind probabilities. Several data sets have been used: daily 1000 geopotential height (Z1000) field over the North Atlantic and the observational daily wind gust (WGU). Next, to give an additional value to the ERA-Interim wind gust data base (ERI), wind gust estimations from the analogue model were obtained to compare them with the wind gust data set from the ERA-Interim. The analogue method is based on finding in the historic geopotential height data base, a principal component subset of geopotential height patterns that are the most akin to a geopotential height pattern used as an input. Then, once the analogues are determined associated wind gusts are estimated from them. Finally, within validation stage are shown some results relative to the comparison between the wind gust estimated and ERI data. The probabilistic results are shown by means of Brier Skill Scores. The results show that the ANPAF model gives good wind gust information in the inner Iberian Peninsula and highlight that the Atlantic atmospheric patterns are, in general, better to predict gusts in such area. Though in only few stations the ANPAF model provides less additional value than the ERA-Interim data base for extreme wind gust values, the analogue model generally provides pretty information in estimating wind gust in Spain to the ERI data set.
Simulation of atmospheric microbursts using a numerical mesoscale model at high spatiotemporal resolution
(American Geophysical Union, 2020-02-05) Bolgiani, Pedro; Fernández González, Sergio; Valero Rodríguez, Francisco; Merino, Andrés; García Ortega, Eduardo; Sánchez, José Luis; Martín, María Luisa
Atmospheric microbursts are low‐level meteorological events that can produce significant damage on the surface and pose a major risk to aircraft flying close to the ground. Studies and ad hoc numerical models have been developed to understand the origin and dynamics of the microburst; nevertheless, there are few researches of the phenomenon using global and mesoscale models. This is mainly due to the limitations in resolution, as microbursts normally span for less than 4 km and 20 min. In this paper, the Weather Research and Forecasting model is used at resolutions of 400 m and 3 min to test if it can properly capture the variables and dynamics of high‐reflectivity microbursts. Several microphysics and planetary boundary layer parametrizations are tested to find the best model configuration for the simulation of this kind of episodes. General conditions are evaluated by using thermodynamic diagrams. Surface and vertical wind speed, reflectivity, precipitation, and other variables for each simulated event are compared with observations, and the model's sensitivity to the variables is assessed. The dynamics and evolution of the microburst is evaluated using different plots of a chosen event. The results show that the model is able to reproduce high‐reflectivity microbursts in accordance with observations, although there is a tendency to underestimate the intensity of variables, most markedly on the wind vertical velocity. Regarding the microphysics schemes, the Morrison parametrization performs better than the WRF single‐moment 6‐class scheme. No major differences are found between the Mellor‐Yamada‐Janjic and the Mellor‐Yamada‐Nakanishi‐Niino planetary boundary layer parametrizations.