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Papers by jeff vinuesa
The chemical lifetime of reactants in the atmosphere can vary within a wide range of time scales.... more The chemical lifetime of reactants in the atmosphere can vary within a wide range of time scales. Some highly reactive compounds such as OH and HO2 radicals have typical time scales smaller than a second. For such species, chemistry can be so active that the chemical compounds react in situ and are hardly transported by the flow. In large eddy simulations (LES) of atmospheric reacting flows, homogeneous and instantaneous mixing of reactants within a grid-cell is normally assumed. However, this assumption can result in large errors in the estimation of the reaction rates due to the fact that highly reactive species can be segregated or pre-mixed at small scales. Since this process occurs at scales smaller than the grid length (sub-grid process), it requires a subgrid parameterization. In this paper, we propose a parameterization for the subgrid chemical transformations. Its formulation relies on the description of the subgrid covariance, i.e. the quantity that accounts for the mixing...
The current understanding of the influence of physical processes on chemical reactions in the atm... more The current understanding of the influence of physical processes on chemical reactions in the atmospheric boundary layer is briefly reviewed. The fundamentals of this influence and the consequences for the transport and mixing of the reactants are discussed. A classification of the turbulent reacting flows is presented in terms of the values of dimensionless numbers. These numbers depend on the characteristic time scale of the dynamics and the chemistry. The main findings obtained by modelling studies of various convective and cloudy boundary layer flows and chemical mechanisms, in particular the ones done by means of the large-eddy simulation technique, are summarised. Based on the conclusions of these studies, we discussed the need to improve, by combining observational and numerical experiments, our knowledge of the role played by physical processes on the transformations of reactive species in the atmospheric boundary layer.
The control of turbulent mixing on the reactivity of species is studied by analyzing the contribu... more The control of turbulent mixing on the reactivity of species is studied by analyzing the contribution of the chemical terms to the governing equations for reactants. For reacting scalars with a short chemical lifetime or with a lifetime at the same order of magnitude as the turnover time of the convective boundary layer (CBL), one should expect that the chemical terms have a large contribution and, as a result, fluxes and (co-)variances deviate from the inert profiles. In this paper, we attempt to give a com- prehensive view of the magnitude of these deviations and of their control parameters. The effect of the chemical terms on transport and mixing of reacting scalars is evalu- ated through exact decomposition of second-order moment budgets using large-eddy simulation (LES). Compared to temperature, moisture and inert scalars for which ex- tensive studies have shown the contribution of the different dynamical terms to the budget of fluxes and (co-)variances, only few studies were d...
The diurnally varying atmospheric boundary layers observed during the Wangara and CASES-99 field ... more The diurnally varying atmospheric boundary layers observed during the Wangara and CASES-99 field campaigns are simulated using the newly proposed locally-averaged scale-dependent dynamic subgrid-scale (SGS) model. This tuning-free SGS model enables one to dynamically compute the Smagorinsky coefficient and the subgrid- scale Prandtl number based on the local dynamics of the resolved velocity and temperature fields. We show that this SGS model-based large-eddy simulation (LES) has the ability to reproduce with great accuracy the characteristics of observed atmospheric boundary layers even with relatively coarse resolutions. In particular, the development, magnitude, and location of an observed nocturnal low-level jet are very well depicted. Some well- established empirical formulations (e.g., mixed layer and local scaling) are recovered with good accuracy by this LES-SGS parameterization. In this presentation, we also delineate the potential of this new-generation dynamic LES-SGS mod...
The objective is to review existing satellite products for irrigation purposes relevant for the E... more The objective is to review existing satellite products for irrigation purposes relevant for the ENORASIS project. A host of international organizations developed and launched operational satellites that provide products of interest for irrigation planning. United States of America organizations are the National Aeronautics and Space Administration (NASA), the Defense Meteorological Satellite Program (DMSP), the Suomi National Polar orbiting Partnership. The satellite missions of European organization for the Exploitation of Meteorological Satellites (EUMETSAT) with the Meteosat Second Generation (MSG) and the EUMETSAT Polar System (EPS) and the European Space Agency (ESA) operational earth observation missions. Several European/USA jointly missions such as TOPEX/Poseidon and Jason - 1 and the Ocean Surface Topography Mission (OSTM) Jason - 2 and the French space agency CNES with the SPOT satellite series. In our study we give an overview of each relevant product, together with infor...
ATMOSPHERIC CHEMISTRY AND PHYSICS
We evaluate the impact of high resolution SRTM topography and Corine Land Cover (LC) data on the ... more We evaluate the impact of high resolution SRTM topography and Corine Land Cover (LC) data on the calculated 10m wind speeds, temperature at 2m (T2) and precipitation in WRF for the Lombardy region (Italy). We compare the results with the simulation using the standard 30-arc seconds USGS LC and with observations of the ARPA network for a winter and summer period in 2008. Our analysis shows that in general calculated average wind speeds are in general lower by WRF with the Corine LC, due to the larger fraction of the urban built-up category and agree better with the observations. Clear differences are found in calculated T2 outside the city of Milan. The probability of detection of rain and the Hansen-Kuipers score are somewhat higher by the simulation with Corine LC.
Meteorological and Air Quality Models for Urban Areas, 2009
A novel approach to account for the spatial variability of the small-scale emission in air qualit... more A novel approach to account for the spatial variability of the small-scale emission in air quality models is proposed. This approach includes a formulation for the sub-grid variability of pollutant concentrations and relates it to the spatial heterogeneity of the emissions. The parameterization is implemented in a 3D transport model and tested against large eddy simulations of convective atmospheric boundary layers.
ABSTRACT In large-eddy simulations of atmospheric boundary layer turbulence, the lumped coe-cient... more ABSTRACT In large-eddy simulations of atmospheric boundary layer turbulence, the lumped coe-cient in the eddy-difiusion subgrid-scale (SGS) model is known to depend on scale for the case of inert scalars. This scale dependence is predominant near the surface. In this paper, a scale-dependent dynamic SGS model for the turbulent transport of reacting scalars is implemented in large-eddy simulations of a neutral boundary layer. Since the model coe-cient is computed dynamically from the dy- namics of the resolved scales, the simulations are free from any parameter tuning. A set of chemical cases representative of various turbulent reacting ∞ow regimes is examined. The reactants are involved in a flrst-order reaction and are injected in the atmospheric boundary layer with a constant and uniform surface ∞ux. Empha- sis is placed on studying the combined efiects of resolution and chemical regime on the performance of the SGS model. Simulations with the scale-dependent dynamic model yield the expected trends of the coe-cients as function of resolution, posi- tion in the ∞ow and fllter scale, leading to resolution-independent turbulent reactant ∞uxes.
The influence of atmospheric turbulence on reactant mixing of pollutants is analysed for various ... more The influence of atmospheric turbulence on reactant mixing of pollutants is analysed for various turbulent reacting flows by using large-eddy simulation (LES). In the convective boundary layer (CBL), the chemical transformations of pollutants depend on the efficiency of atmospheric turbulence to mix the reactants. The CBL is characterised by vigorous thermals (updraft motions) surrounded by subsidence motions. In such a flow, reactants are normally segregated and as a consequence the reaction rate is slowed down. At large atmospheric models, this process occurs in scales smaller than the grid length (sub-grid process), and therefore it requires a description in term of a parameterisation. Based on our LES results, we develop a parameterisation that represents the segregation of reacting species in large-scale models under convective conditions. In its derivation, we use the LES results to account explicitly for the chemical contribution to the covariance of the concentration distrib...
Meteorology and Atmospheric Physics, 2004
Journal of Applied Meteorology and Climatology, 2008
The diurnally varying atmospheric boundary layer observed during the Wangara (Australia) case stu... more The diurnally varying atmospheric boundary layer observed during the Wangara (Australia) case study is simulated using the recently proposed locally averaged scale-dependent dynamic subgrid-scale (SGS) model. This tuning-free SGS model enables one to dynamically compute the Smagorinsky coefficient and the subgrid-scale Prandtl number based on the local dynamics of the resolved velocity and temperature fields. It is shown that this SGS-model-based large-eddy simulation (LES) has the ability to faithfully reproduce the characteristics of observed atmospheric boundary layers even with relatively coarse resolutions. In particular, the development, magnitude, and location of an observed nocturnal low-level jet are depicted quite well. Some well-established empirical formulations (e.g., mixed layer scaling, spectral scaling) are recovered with good accuracy by this SGS parameterization. The application of this new-generation dynamic SGS modeling approach is also briefly delineated to addr...
The chemical lifetime of reactants in the atmosphere can vary within a wide range of time scales.... more The chemical lifetime of reactants in the atmosphere can vary within a wide range of time scales. Some highly reactive compounds such as OH and HO2 radicals have typical time scales smaller than a second. For such species, chemistry can be so active that the chemical compounds react in situ and are hardly transported by the flow. In large eddy simulations (LES) of atmospheric reacting flows, homogeneous and instantaneous mixing of reactants within a grid-cell is normally assumed. However, this assumption can result in large errors in the estimation of the reaction rates due to the fact that highly reactive species can be segregated or pre-mixed at small scales. Since this process occurs at scales smaller than the grid length (sub-grid process), it requires a subgrid parameterization. In this paper, we propose a parameterization for the subgrid chemical transformations. Its formulation relies on the description of the subgrid covariance, i.e. the quantity that accounts for the mixing...
The current understanding of the influence of physical processes on chemical reactions in the atm... more The current understanding of the influence of physical processes on chemical reactions in the atmospheric boundary layer is briefly reviewed. The fundamentals of this influence and the consequences for the transport and mixing of the reactants are discussed. A classification of the turbulent reacting flows is presented in terms of the values of dimensionless numbers. These numbers depend on the characteristic time scale of the dynamics and the chemistry. The main findings obtained by modelling studies of various convective and cloudy boundary layer flows and chemical mechanisms, in particular the ones done by means of the large-eddy simulation technique, are summarised. Based on the conclusions of these studies, we discussed the need to improve, by combining observational and numerical experiments, our knowledge of the role played by physical processes on the transformations of reactive species in the atmospheric boundary layer.
The control of turbulent mixing on the reactivity of species is studied by analyzing the contribu... more The control of turbulent mixing on the reactivity of species is studied by analyzing the contribution of the chemical terms to the governing equations for reactants. For reacting scalars with a short chemical lifetime or with a lifetime at the same order of magnitude as the turnover time of the convective boundary layer (CBL), one should expect that the chemical terms have a large contribution and, as a result, fluxes and (co-)variances deviate from the inert profiles. In this paper, we attempt to give a com- prehensive view of the magnitude of these deviations and of their control parameters. The effect of the chemical terms on transport and mixing of reacting scalars is evalu- ated through exact decomposition of second-order moment budgets using large-eddy simulation (LES). Compared to temperature, moisture and inert scalars for which ex- tensive studies have shown the contribution of the different dynamical terms to the budget of fluxes and (co-)variances, only few studies were d...
The diurnally varying atmospheric boundary layers observed during the Wangara and CASES-99 field ... more The diurnally varying atmospheric boundary layers observed during the Wangara and CASES-99 field campaigns are simulated using the newly proposed locally-averaged scale-dependent dynamic subgrid-scale (SGS) model. This tuning-free SGS model enables one to dynamically compute the Smagorinsky coefficient and the subgrid- scale Prandtl number based on the local dynamics of the resolved velocity and temperature fields. We show that this SGS model-based large-eddy simulation (LES) has the ability to reproduce with great accuracy the characteristics of observed atmospheric boundary layers even with relatively coarse resolutions. In particular, the development, magnitude, and location of an observed nocturnal low-level jet are very well depicted. Some well- established empirical formulations (e.g., mixed layer and local scaling) are recovered with good accuracy by this LES-SGS parameterization. In this presentation, we also delineate the potential of this new-generation dynamic LES-SGS mod...
The objective is to review existing satellite products for irrigation purposes relevant for the E... more The objective is to review existing satellite products for irrigation purposes relevant for the ENORASIS project. A host of international organizations developed and launched operational satellites that provide products of interest for irrigation planning. United States of America organizations are the National Aeronautics and Space Administration (NASA), the Defense Meteorological Satellite Program (DMSP), the Suomi National Polar orbiting Partnership. The satellite missions of European organization for the Exploitation of Meteorological Satellites (EUMETSAT) with the Meteosat Second Generation (MSG) and the EUMETSAT Polar System (EPS) and the European Space Agency (ESA) operational earth observation missions. Several European/USA jointly missions such as TOPEX/Poseidon and Jason - 1 and the Ocean Surface Topography Mission (OSTM) Jason - 2 and the French space agency CNES with the SPOT satellite series. In our study we give an overview of each relevant product, together with infor...
ATMOSPHERIC CHEMISTRY AND PHYSICS
We evaluate the impact of high resolution SRTM topography and Corine Land Cover (LC) data on the ... more We evaluate the impact of high resolution SRTM topography and Corine Land Cover (LC) data on the calculated 10m wind speeds, temperature at 2m (T2) and precipitation in WRF for the Lombardy region (Italy). We compare the results with the simulation using the standard 30-arc seconds USGS LC and with observations of the ARPA network for a winter and summer period in 2008. Our analysis shows that in general calculated average wind speeds are in general lower by WRF with the Corine LC, due to the larger fraction of the urban built-up category and agree better with the observations. Clear differences are found in calculated T2 outside the city of Milan. The probability of detection of rain and the Hansen-Kuipers score are somewhat higher by the simulation with Corine LC.
Meteorological and Air Quality Models for Urban Areas, 2009
A novel approach to account for the spatial variability of the small-scale emission in air qualit... more A novel approach to account for the spatial variability of the small-scale emission in air quality models is proposed. This approach includes a formulation for the sub-grid variability of pollutant concentrations and relates it to the spatial heterogeneity of the emissions. The parameterization is implemented in a 3D transport model and tested against large eddy simulations of convective atmospheric boundary layers.
ABSTRACT In large-eddy simulations of atmospheric boundary layer turbulence, the lumped coe-cient... more ABSTRACT In large-eddy simulations of atmospheric boundary layer turbulence, the lumped coe-cient in the eddy-difiusion subgrid-scale (SGS) model is known to depend on scale for the case of inert scalars. This scale dependence is predominant near the surface. In this paper, a scale-dependent dynamic SGS model for the turbulent transport of reacting scalars is implemented in large-eddy simulations of a neutral boundary layer. Since the model coe-cient is computed dynamically from the dy- namics of the resolved scales, the simulations are free from any parameter tuning. A set of chemical cases representative of various turbulent reacting ∞ow regimes is examined. The reactants are involved in a flrst-order reaction and are injected in the atmospheric boundary layer with a constant and uniform surface ∞ux. Empha- sis is placed on studying the combined efiects of resolution and chemical regime on the performance of the SGS model. Simulations with the scale-dependent dynamic model yield the expected trends of the coe-cients as function of resolution, posi- tion in the ∞ow and fllter scale, leading to resolution-independent turbulent reactant ∞uxes.
The influence of atmospheric turbulence on reactant mixing of pollutants is analysed for various ... more The influence of atmospheric turbulence on reactant mixing of pollutants is analysed for various turbulent reacting flows by using large-eddy simulation (LES). In the convective boundary layer (CBL), the chemical transformations of pollutants depend on the efficiency of atmospheric turbulence to mix the reactants. The CBL is characterised by vigorous thermals (updraft motions) surrounded by subsidence motions. In such a flow, reactants are normally segregated and as a consequence the reaction rate is slowed down. At large atmospheric models, this process occurs in scales smaller than the grid length (sub-grid process), and therefore it requires a description in term of a parameterisation. Based on our LES results, we develop a parameterisation that represents the segregation of reacting species in large-scale models under convective conditions. In its derivation, we use the LES results to account explicitly for the chemical contribution to the covariance of the concentration distrib...
Meteorology and Atmospheric Physics, 2004
Journal of Applied Meteorology and Climatology, 2008
The diurnally varying atmospheric boundary layer observed during the Wangara (Australia) case stu... more The diurnally varying atmospheric boundary layer observed during the Wangara (Australia) case study is simulated using the recently proposed locally averaged scale-dependent dynamic subgrid-scale (SGS) model. This tuning-free SGS model enables one to dynamically compute the Smagorinsky coefficient and the subgrid-scale Prandtl number based on the local dynamics of the resolved velocity and temperature fields. It is shown that this SGS-model-based large-eddy simulation (LES) has the ability to faithfully reproduce the characteristics of observed atmospheric boundary layers even with relatively coarse resolutions. In particular, the development, magnitude, and location of an observed nocturnal low-level jet are depicted quite well. Some well-established empirical formulations (e.g., mixed layer scaling, spectral scaling) are recovered with good accuracy by this SGS parameterization. The application of this new-generation dynamic SGS modeling approach is also briefly delineated to addr...