The broken-symmetry electroweak vacuum is destabilized in the presence of a magnetic field strong... more The broken-symmetry electroweak vacuum is destabilized in the presence of a magnetic field stronger than a critical value. Such magnetic field may be generated in the phase transition and restore the symmetry inside the bubbles. A numerical calculation indicates that the first-order phase transition is delayed but may be completed for a sufficient low value of the Higgs mass unless the magnetic field is extremely high.
INTRODUCTION The vertical distribution for a point source plume is studied through the statistica... more INTRODUCTION The vertical distribution for a point source plume is studied through the statistical descriptors derived from the analytical solution of the advection-diffusion equation. Traditionally operative modelling for dispersion has been performed adopting a Gaussian approach taking in account atmospheric turbulence assuming simple formulae for concentration distribution, where the parameterization depend simply on downwind distance as well as the meteorological state of ABL (Arya, 1999). Regarding the vertical dispersion the scheme performs adequately for short horizontal distances and for near ground sources only. Within this scheme the low source condition has the effect of the crude approximation of infinite height of the ABL. The Gaussian approach turns out to overestimate the centroid z and the
ABSTRACT The effects of the numerical scheme implemented in the advection equation of BOLCHEM hav... more ABSTRACT The effects of the numerical scheme implemented in the advection equation of BOLCHEM have been quantified with reference to the diffusion of a passive tracer. An equivalent horizontal diffusion coefficient has been measured and is found to be dependent on wind field and resolution.
The Advection-Diffusion Equation (ADE) is solved for a constant pollutant emission from a point-l... more The Advection-Diffusion Equation (ADE) is solved for a constant pollutant emission from a point-like source placed inside an unstable Atmospheric Boundary Layer (ABL). The solution is obtained adopting the novel analytical approach named Generalized Integral Laplace Transform Technique (GILTT). The concentration solution of the equation is expressed through an infinite series expansion. After setting a realistic scenario through the wind
Satellite remote sensing of both trace gas constituents and Particulate Matter (PM) can be profit... more Satellite remote sensing of both trace gas constituents and Particulate Matter (PM) can be profitably exploited in the Air Quality field by combining satellite observations with regional meteorological modelling and ground-based measurements. With regard to this, the capability of MODIS sensors (Terra and Aqua/NASA platforms) to retrieve aerosol optical properties has been used in a semi-empirical approach to estimate PM content at the ground over a domain containing whole Northern Italy. Daily maps of satellite-based PM2.5 concentrations over Northern Italy have been derived. Daily estimates and monthly averaged values have been compared to in-situ PM2.5 sampling providing a good agreement, with the MODIS-based concentrations tending to underestimate the values by at most 20%. These findings represent the direct outcome of the prototype Satellite-based Particulate Matter demonstration service developed in strict synergy between QUITSAT project (2006-2009) - funded by the Italian Space Agency - and PROMOTE project (2006-2009) - supported by the European Space Agency. In both projects a significant role has been played by regional environmental agencies - ARPA - of 3 regions located in the Po valley area (Emilia Romagna, Piedmont and Lombardia) acting as Users and analyzing the quality of the achieved satellite-based products and service performances. Relying on the experience achieved within these projects, ARPA users have expressed the interest in providing requirements, following the development, and testing the core-downstream-end user service chain in O-INTERFACE MACC subproject funded under the EU 7th Framework Program and the forthcoming EU 7th FP PASODOBLE project.
Satellite remote sensing of aerosols and trace gas constituents is a well established technique w... more Satellite remote sensing of aerosols and trace gas constituents is a well established technique which has been mainly applied to radiative forcing and climate studies. Over recent years growing attention has been paid to its potential application in the field of air quality and in particular to the possibility of monitoring surface Particulate Matter (PM) concentrations. Actually the relationship between the aerosol optical depth (AOD) at 550 nm wavelength and surface PM concentrations has been subject to several investigations. Such a relationship between a measure of the columnar aerosol extinction in the visible and a concentration in-situ sampling is substantially influenced by the region, the season, as well as the vertical distribution profile and microphysical properties of the suspended aerosol polydispersion. On the basis of these remarks, a semi-empirical method has been developed to estimate PM2.5 concentration at ground level employing MODIS (Terra-Aqua/NASA platforms) aerosol optical properties. This approach fuses PM2.5 samplings at the ground, meteorological fields simulated by MM5 model, ground-based remote sensing measurements and MODIS aerosol optical depth to convert AOD into PM estimates. Thus, daily maps of satellite-based PM2.5 concentrations over Northern Italy were obtained. Comparison with daily PM2.5, sampled at six validation sites of the Po valley in summer 2007 and winter 2008, showed good agreement (presenting regression coefficient R ~0.82 and R ~0.77 for MODIS/Terra and MODIS/Aqua, respectively), with the satellite-based concentrations tending to underestimate the values by no more than ~20%. Monthly averaged values were also compared finding a good agreement, with R ~0.83 for each platform. The results were carried out in the frame of the QUITSAT/ASI and PROMOTE/ESA projects, and encouraged us to continue in improving this methodology in the frame of EU 7th Framework MACC and PASODOBLE projects.
Satellite remote sensing of aerosols and trace gas constituents is a well established technique w... more Satellite remote sensing of aerosols and trace gas constituents is a well established technique which has been mainly applied to radiative forcing and climate studies. Over recent years growing attention has been paid to its potential application in the field of air quality and in particular to the possibility of monitoring surface Particulate Matter (PM) concentrations. Actually the relationship between the aerosol optical depth (AOD) at 550 nm wavelength and surface PM concentrations has been subject to several investigations. Such a relationship between a measure of the columnar aerosol extinction in the visible and a concentration in-situ sampling is substantially influenced by the region, the season, as well as the vertical distribution profile and microphysical properties of the suspended aerosol polydispersion. On the basis of these remarks, a semi-empirical method has been developed to estimate PM2.5 concentration at ground level employing MODIS (Terra-Aqua/NASA platforms) aerosol optical properties. This approach fuses PM2.5 samplings at the ground, meteorological fields simulated by MM5 model, ground-based remote sensing measurements and MODIS aerosol optical depth to convert AOD into PM estimates. Thus, daily maps of satellite-based PM2.5 concentrations over Northern Italy were obtained. Comparison with daily PM2.5, sampled at six validation sites of the Po valley in summer 2007 and winter 2008, showed good agreement (presenting regression coefficient R ~0.82 and R ~0.77 for MODIS/Terra and MODIS/Aqua, respectively), with the satellite-based concentrations tending to underestimate the values by no more than ~20%. Monthly averaged values were also compared finding a good agreement, with R ~0.83 for each platform. The results were carried out in the frame of the QUITSAT/ASI and PROMOTE/ESA projects, and encouraged us to continue in improving this methodology in the frame of EU 7th Framework MACC and PASODOBLE projects.
Satellite remote sensing of both trace gas constituents and Particulate Matter (PM) can be profit... more Satellite remote sensing of both trace gas constituents and Particulate Matter (PM) can be profitably exploited in the Air Quality field by combining satellite observations with regional meteorological modelling and ground-based measurements. With regard to this, the capability of MODIS sensors (Terra and Aqua/NASA platforms) to retrieve aerosol optical properties has been used in a semi-empirical approach to estimate PM content at the ground over a domain containing whole Northern Italy. Daily maps of satellite-based PM2.5 concentrations over Northern Italy have been derived. Daily estimates and monthly averaged values have been compared to in-situ PM2.5 sampling providing a good agreement, with the MODIS-based concentrations tending to underestimate the values by at most 20%. These findings represent the direct outcome of the prototype Satellite-based Particulate Matter demonstration service developed in strict synergy between QUITSAT project (2006-2009) - funded by the Italian Space Agency - and PROMOTE project (2006-2009) - supported by the European Space Agency. In both projects a significant role has been played by regional environmental agencies - ARPA - of 3 regions located in the Po valley area (Emilia Romagna, Piedmont and Lombardia) acting as Users and analyzing the quality of the achieved satellite-based products and service performances. Relying on the experience achieved within these projects, ARPA users have expressed the interest in providing requirements, following the development, and testing the core-downstream-end user service chain in O-INTERFACE MACC subproject funded under the EU 7th Framework Program and the forthcoming EU 7th FP PASODOBLE project.
The broken-symmetry electroweak vacuum is destabilized in the presence of a magnetic field strong... more The broken-symmetry electroweak vacuum is destabilized in the presence of a magnetic field stronger than a critical value. Such magnetic field may be generated in the phase transition and restore the symmetry inside the bubbles. A numerical calculation indicates that the first-order phase transition is delayed but may be completed for a sufficient low value of the Higgs mass unless the magnetic field is extremely high.
INTRODUCTION The vertical distribution for a point source plume is studied through the statistica... more INTRODUCTION The vertical distribution for a point source plume is studied through the statistical descriptors derived from the analytical solution of the advection-diffusion equation. Traditionally operative modelling for dispersion has been performed adopting a Gaussian approach taking in account atmospheric turbulence assuming simple formulae for concentration distribution, where the parameterization depend simply on downwind distance as well as the meteorological state of ABL (Arya, 1999). Regarding the vertical dispersion the scheme performs adequately for short horizontal distances and for near ground sources only. Within this scheme the low source condition has the effect of the crude approximation of infinite height of the ABL. The Gaussian approach turns out to overestimate the centroid z and the
ABSTRACT The effects of the numerical scheme implemented in the advection equation of BOLCHEM hav... more ABSTRACT The effects of the numerical scheme implemented in the advection equation of BOLCHEM have been quantified with reference to the diffusion of a passive tracer. An equivalent horizontal diffusion coefficient has been measured and is found to be dependent on wind field and resolution.
The Advection-Diffusion Equation (ADE) is solved for a constant pollutant emission from a point-l... more The Advection-Diffusion Equation (ADE) is solved for a constant pollutant emission from a point-like source placed inside an unstable Atmospheric Boundary Layer (ABL). The solution is obtained adopting the novel analytical approach named Generalized Integral Laplace Transform Technique (GILTT). The concentration solution of the equation is expressed through an infinite series expansion. After setting a realistic scenario through the wind
Satellite remote sensing of both trace gas constituents and Particulate Matter (PM) can be profit... more Satellite remote sensing of both trace gas constituents and Particulate Matter (PM) can be profitably exploited in the Air Quality field by combining satellite observations with regional meteorological modelling and ground-based measurements. With regard to this, the capability of MODIS sensors (Terra and Aqua/NASA platforms) to retrieve aerosol optical properties has been used in a semi-empirical approach to estimate PM content at the ground over a domain containing whole Northern Italy. Daily maps of satellite-based PM2.5 concentrations over Northern Italy have been derived. Daily estimates and monthly averaged values have been compared to in-situ PM2.5 sampling providing a good agreement, with the MODIS-based concentrations tending to underestimate the values by at most 20%. These findings represent the direct outcome of the prototype Satellite-based Particulate Matter demonstration service developed in strict synergy between QUITSAT project (2006-2009) - funded by the Italian Space Agency - and PROMOTE project (2006-2009) - supported by the European Space Agency. In both projects a significant role has been played by regional environmental agencies - ARPA - of 3 regions located in the Po valley area (Emilia Romagna, Piedmont and Lombardia) acting as Users and analyzing the quality of the achieved satellite-based products and service performances. Relying on the experience achieved within these projects, ARPA users have expressed the interest in providing requirements, following the development, and testing the core-downstream-end user service chain in O-INTERFACE MACC subproject funded under the EU 7th Framework Program and the forthcoming EU 7th FP PASODOBLE project.
Satellite remote sensing of aerosols and trace gas constituents is a well established technique w... more Satellite remote sensing of aerosols and trace gas constituents is a well established technique which has been mainly applied to radiative forcing and climate studies. Over recent years growing attention has been paid to its potential application in the field of air quality and in particular to the possibility of monitoring surface Particulate Matter (PM) concentrations. Actually the relationship between the aerosol optical depth (AOD) at 550 nm wavelength and surface PM concentrations has been subject to several investigations. Such a relationship between a measure of the columnar aerosol extinction in the visible and a concentration in-situ sampling is substantially influenced by the region, the season, as well as the vertical distribution profile and microphysical properties of the suspended aerosol polydispersion. On the basis of these remarks, a semi-empirical method has been developed to estimate PM2.5 concentration at ground level employing MODIS (Terra-Aqua/NASA platforms) aerosol optical properties. This approach fuses PM2.5 samplings at the ground, meteorological fields simulated by MM5 model, ground-based remote sensing measurements and MODIS aerosol optical depth to convert AOD into PM estimates. Thus, daily maps of satellite-based PM2.5 concentrations over Northern Italy were obtained. Comparison with daily PM2.5, sampled at six validation sites of the Po valley in summer 2007 and winter 2008, showed good agreement (presenting regression coefficient R ~0.82 and R ~0.77 for MODIS/Terra and MODIS/Aqua, respectively), with the satellite-based concentrations tending to underestimate the values by no more than ~20%. Monthly averaged values were also compared finding a good agreement, with R ~0.83 for each platform. The results were carried out in the frame of the QUITSAT/ASI and PROMOTE/ESA projects, and encouraged us to continue in improving this methodology in the frame of EU 7th Framework MACC and PASODOBLE projects.
Satellite remote sensing of aerosols and trace gas constituents is a well established technique w... more Satellite remote sensing of aerosols and trace gas constituents is a well established technique which has been mainly applied to radiative forcing and climate studies. Over recent years growing attention has been paid to its potential application in the field of air quality and in particular to the possibility of monitoring surface Particulate Matter (PM) concentrations. Actually the relationship between the aerosol optical depth (AOD) at 550 nm wavelength and surface PM concentrations has been subject to several investigations. Such a relationship between a measure of the columnar aerosol extinction in the visible and a concentration in-situ sampling is substantially influenced by the region, the season, as well as the vertical distribution profile and microphysical properties of the suspended aerosol polydispersion. On the basis of these remarks, a semi-empirical method has been developed to estimate PM2.5 concentration at ground level employing MODIS (Terra-Aqua/NASA platforms) aerosol optical properties. This approach fuses PM2.5 samplings at the ground, meteorological fields simulated by MM5 model, ground-based remote sensing measurements and MODIS aerosol optical depth to convert AOD into PM estimates. Thus, daily maps of satellite-based PM2.5 concentrations over Northern Italy were obtained. Comparison with daily PM2.5, sampled at six validation sites of the Po valley in summer 2007 and winter 2008, showed good agreement (presenting regression coefficient R ~0.82 and R ~0.77 for MODIS/Terra and MODIS/Aqua, respectively), with the satellite-based concentrations tending to underestimate the values by no more than ~20%. Monthly averaged values were also compared finding a good agreement, with R ~0.83 for each platform. The results were carried out in the frame of the QUITSAT/ASI and PROMOTE/ESA projects, and encouraged us to continue in improving this methodology in the frame of EU 7th Framework MACC and PASODOBLE projects.
Satellite remote sensing of both trace gas constituents and Particulate Matter (PM) can be profit... more Satellite remote sensing of both trace gas constituents and Particulate Matter (PM) can be profitably exploited in the Air Quality field by combining satellite observations with regional meteorological modelling and ground-based measurements. With regard to this, the capability of MODIS sensors (Terra and Aqua/NASA platforms) to retrieve aerosol optical properties has been used in a semi-empirical approach to estimate PM content at the ground over a domain containing whole Northern Italy. Daily maps of satellite-based PM2.5 concentrations over Northern Italy have been derived. Daily estimates and monthly averaged values have been compared to in-situ PM2.5 sampling providing a good agreement, with the MODIS-based concentrations tending to underestimate the values by at most 20%. These findings represent the direct outcome of the prototype Satellite-based Particulate Matter demonstration service developed in strict synergy between QUITSAT project (2006-2009) - funded by the Italian Space Agency - and PROMOTE project (2006-2009) - supported by the European Space Agency. In both projects a significant role has been played by regional environmental agencies - ARPA - of 3 regions located in the Po valley area (Emilia Romagna, Piedmont and Lombardia) acting as Users and analyzing the quality of the achieved satellite-based products and service performances. Relying on the experience achieved within these projects, ARPA users have expressed the interest in providing requirements, following the development, and testing the core-downstream-end user service chain in O-INTERFACE MACC subproject funded under the EU 7th Framework Program and the forthcoming EU 7th FP PASODOBLE project.
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