The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Martin Piringer - One of the best experts on this subject based on the ideXlab platform.
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Mixing Height time series from operational ceilometer aerosol layer Heights
Boundary-Layer Meteorology, 2016Co-Authors: Christoph Lotteraner, Martin PiringerAbstract:A new method is described to derive Mixing-Height time series directly from aerosol-layer Height data available from a Vaisala CL51 ceilometer. As complete as possible Mixing-Height time series are calculated by avoiding outliers, filling data gaps by linear interpolation, and smoothing. In addition, large aerosol-layer Heights at night that can be interpreted as residual layers are not assigned as Mixing Heights. The resulting Mixing-Height time series, converted to an appropriate data format, can be used as input for dispersion calculations. Two case examples demonstrate in detail how the method works. The Mixing Heights calculated using ceilometer data are compared with values determined from radiosounding data at Vienna by applying the parcel, Heffter, and Richardson methods. The results of the parcel method, obtained from radiosonde profiles at noon, show the best fit to the ceilometer-derived Mixing Heights. For midnight radiosoundings, larger deviations between Mixing Heights from the ceilometer and those deduced from the potential temperature profiles of the soundings are found. We use data from two Vaisala CL51 ceilometers, operating in the Vienna area at an urban and rural site, respectively, during an overlapping period of about 1 year. In addition to the case studies, the calculated Mixing-Height time series are also statistically evaluated and compared, demonstrating that the ceilometer-based Mixing Height follows an expected daily and seasonal course.
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The surface energy balance and the Mixing Height in urban areas—activities and recommendations of COST-Action 715
Boundary-Layer Meteorology, 2007Co-Authors: Martin Piringer, Alexander Baklanov, Sylvain Joffre, Andreas Christen, Marco Deserti, Koen Ridder, Stefan Emeis, Patrice Mestayer, Maria Tombrou, Douglas MiddletonAbstract:The specific problems of determining and simulating the surface energy balance (SEB) and the Mixing Height (MH) over urban areas are examined. The SEB and MH are critical components of algorithms and numerical models for the urban boundary layer, though the constituent parts of the SEB and the MH are not routinely measured by national weather services. Parameterisations are thus needed in applications. In this investigation, several recently developed algorithms and models for estimating the SEB and MH were applied to new datasets and assessed. Results are discussed in terms of the need for spatial resolution and the parameters needed to describe the urban atmosphere. Limitations of models are identified and recommendations for further development and observations are given. Having identified gaps in knowledge, key findings from new urban experiments and numerical modelling for the SEB and MH are given. The diurnal cycle for the SEB is significantly different from rural conditions—urban heat storage is needed in urban parameterisations. The urban MH is increased over the rural MH, as shown by several numerical schemes and careful sodar analyses. This work has been carried out within the COST-715 Action “Meteorology applied to urban air pollution problems (1998–2004). COST 715 reached a consensus proposing representatively sited measurements of meteorological parameters and turbulent fluxes above roof-tops, and recognised that such data are needed to improve numerical models of the urban surface processes.
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the surface energy balance and the Mixing Height in urban areas activities and recommendations of cost action 715
Boundary-Layer Meteorology, 2007Co-Authors: Martin Piringer, S Joffre, M. Tombrou, Alexander Baklanov, Andreas Christen, Marco Deserti, Koen Ridder, Stefan Emeis, Patrice Mestayer, D R MiddletonAbstract:The specific problems of determining and simulating the surface energy balance (SEB) and the Mixing Height (MH) over urban areas are examined. The SEB and MH are critical components of algorithms and numerical models for the urban boundary layer, though the constituent parts of the SEB and the MH are not routinely measured by national weather services. Parameterisations are thus needed in applications. In this investigation, several recently developed algorithms and models for estimating the SEB and MH were applied to new datasets and assessed. Results are discussed in terms of the need for spatial resolution and the parameters needed to describe the urban atmosphere. Limitations of models are identified and recommendations for further development and observations are given. Having identified gaps in knowledge, key findings from new urban experiments and numerical modelling for the SEB and MH are given. The diurnal cycle for the SEB is significantly different from rural conditions—urban heat storage is needed in urban parameterisations. The urban MH is increased over the rural MH, as shown by several numerical schemes and careful sodar analyses. This work has been carried out within the COST-715 Action “Meteorology applied to urban air pollution problems (1998–2004). COST 715 reached a consensus proposing representatively sited measurements of meteorological parameters and turbulent fluxes above roof-tops, and recognised that such data are needed to improve numerical models of the urban surface processes.
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Summertime Mixing Heights At Vienna, Austria, Estimated from Vertical Soundings and by a Numerical Model
Boundary-Layer Meteorology, 1998Co-Authors: Martin PiringerAbstract:Mixing Heights calculated by the Danish OML meteorological pre-processor are compared to those diagnosed from radio- and tether-sonde vertical potential temperature profiles. All methods give reliable estimates of noon Mixing Heights deduced from radiosoundings, especially when the boundary layer is fully convective. Differences are larger during convective conditions without a well-defined capping inversion in the radiosonde potential temperature profile or when OML calculates a mechanical Mixing Height. The OML model is also able to calculate the daily course of the Mixing Height as expected. The tethersonde-derived Mixing Heights are especially valuable during the morning rise of the elevated inversion. Modifications to all three methods to improve Mixing-Height predictions are discussed.
Frank Beyrich - One of the best experts on this subject based on the ideXlab platform.
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Chapter 20 Review and intercomparison of operational methods for the determination of the Mixing Height
Developments in environmental science, 2007Co-Authors: Petra Seibert, Frank Beyrich, S Joffre, Svenerik Gryning, Alix Rasmussen, Philippe TercierAbstract:Abstract The Height of the atmospheric boundary layer (ABL) or the Mixing Height (MH) is a fundamental parameter characterising the structure of the lower troposphere. Two basic possibilities for the practical determination of the MH are its derivation from profile data (measurements or numerical model output) and its parameterisation using simple equations or models (which only need a few measured input values). Different methods suggested in the literature are reviewed in this paper. The most important methods have been tested on data sets from three different sites in Europe (Cabauw—NL, Payerne—CH, Melpitz—D). Parcel and Richardson number methods applied to radiosonde profiles and the analysis of sodar and wind profiler data have been investigated. Modules for MH determination implemented in five currently used meteorological preprocessors for dispersion models have been tested, too. Parcel methods using a revised coefficient for the excess temperature and Richardson number methods using a surface excess temperature worked well under convective conditions. Under stable conditions, the inherent difficulties call for a combination of several methods (e.g., mast and sodar). All the tested parameterisation schemes showed deficiencies under certain conditions, thus requiring more flexible algorithms able to take into account changing and non-classical conditions. Recommendations are formulated regarding both the analysis of profile measurements and the use of parameterisations and simple models, and suggestions for the preprocessor development and for future research activities are presented.
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review and intercomparison of operational methods for the determination of the Mixing Height
Atmospheric Environment, 2000Co-Authors: Petra Seibert, Frank Beyrich, S Joffre, Svenerik Gryning, Alix Rasmussen, Philippe TercierAbstract:Abstract The Height of the atmospheric boundary layer (ABL) or the Mixing Height (MH) is a fundamental parameter characterising the structure of the lower troposphere. Two basic possibilities for the practical determination of the MH are its derivation from profile data (measurements or numerical model output) and its parameterisation using simple equations or models (which only need a few measured input values). Different methods suggested in the literature are reviewed in this paper. The most important methods have been tested on data sets from three different sites in Europe (Cabauw – NL, Payerne – CH, Melpitz – D). Parcel and Richardson number methods applied to radiosonde profiles and the analysis of sodar and wind profiler data have been investigated. Modules for MH determination implemented in five currently used meteorological preprocessors for dispersion models have been tested, too. Parcel methods using a revised coefficient for the excess temperature and Richardson number methods using a surface excess temperature worked well under convective conditions. Under stable conditions, the inherent difficulties call for a combination of several methods (e.g., mast and sodar). All the tested parameterisation schemes showed deficiencies under certain conditions, thus requiring more flexible algorithms able to take into account changing and non-classical conditions. Recommendations are formulated regarding both the analysis of profile measurements and the use of parameterisations and simple models, and suggestions for the preprocessor development and for future research activities are presented.
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Mixing Height determination for dispersion modelling a test of meteorological pre processors
22nd NATO CCMS International Technical Meeting, 1998Co-Authors: Frank Beyrich, S Joffre, Svenerik Gryning, Alix Rasmussen, Petra Seibert, Philippe TercierAbstract:Concentrations of atmospheric trace constituents in the atmospheric boundary layer (ABL) are strongly affected by the meteorological conditions. One of the most important parameters to characterize the dispersion potential of the ABL is the Mixing Height (MH). In dispersion models, the MH is a key parameter needed to determine the turbulent domain in which dispersion takes place or as a scaling parameter to describe the vertical profiles of ABL-variables.
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Mixing Height estimation from sodar data a critical discussion
Atmospheric Environment, 1997Co-Authors: Frank BeyrichAbstract:Abstract Sodar measurements have been used to estimate the Mixing Height for about 20 yr, nevertheless the issue is still the subject of controversial discussion. The paper attempts to critically examine the methods and results of Mixing Height determination from sodar data that have been reported in the literature. The theoretical base, the methods suggested, the automatization of algorithms, and the intercomparison of sodar-based Mixing Height values with data from independent measurements and models are briefly discussed. An assessment is given of sodar capabilities in comparison with other profiling techniques. It is concluded that sodar data may be used to derive reliable Mixing Height information in many situations which are of special relevance for environmental monitoring, namely in stagnant weather situations with low Mixing Height values between about 50 and 500–1000 m, depending on the type of the sodar. However, the algorithms available up to now for their automatic evaluation appear not yet reliable enough to be recommended for operational purposes, and a control of the output by a trained analyst is advisable. Simultaneous operation of sodars and other remote sensing systems (lidar, wind profiler) is shown to be a promising way to overcome the range limitations of sodars and to allow continuous Mixing Height estimation throughout the complete diurnal cycle.
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Mixing Height estimation from sodar data — A critical discussion☆
Atmospheric Environment, 1997Co-Authors: Frank BeyrichAbstract:Abstract Sodar measurements have been used to estimate the Mixing Height for about 20 yr, nevertheless the issue is still the subject of controversial discussion. The paper attempts to critically examine the methods and results of Mixing Height determination from sodar data that have been reported in the literature. The theoretical base, the methods suggested, the automatization of algorithms, and the intercomparison of sodar-based Mixing Height values with data from independent measurements and models are briefly discussed. An assessment is given of sodar capabilities in comparison with other profiling techniques. It is concluded that sodar data may be used to derive reliable Mixing Height information in many situations which are of special relevance for environmental monitoring, namely in stagnant weather situations with low Mixing Height values between about 50 and 500–1000 m, depending on the type of the sodar. However, the algorithms available up to now for their automatic evaluation appear not yet reliable enough to be recommended for operational purposes, and a control of the output by a trained analyst is advisable. Simultaneous operation of sodars and other remote sensing systems (lidar, wind profiler) is shown to be a promising way to overcome the range limitations of sodars and to allow continuous Mixing Height estimation throughout the complete diurnal cycle.
Alexander Baklanov - One of the best experts on this subject based on the ideXlab platform.
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The surface energy balance and the Mixing Height in urban areas—activities and recommendations of COST-Action 715
Boundary-Layer Meteorology, 2007Co-Authors: Martin Piringer, Alexander Baklanov, Sylvain Joffre, Andreas Christen, Marco Deserti, Koen Ridder, Stefan Emeis, Patrice Mestayer, Maria Tombrou, Douglas MiddletonAbstract:The specific problems of determining and simulating the surface energy balance (SEB) and the Mixing Height (MH) over urban areas are examined. The SEB and MH are critical components of algorithms and numerical models for the urban boundary layer, though the constituent parts of the SEB and the MH are not routinely measured by national weather services. Parameterisations are thus needed in applications. In this investigation, several recently developed algorithms and models for estimating the SEB and MH were applied to new datasets and assessed. Results are discussed in terms of the need for spatial resolution and the parameters needed to describe the urban atmosphere. Limitations of models are identified and recommendations for further development and observations are given. Having identified gaps in knowledge, key findings from new urban experiments and numerical modelling for the SEB and MH are given. The diurnal cycle for the SEB is significantly different from rural conditions—urban heat storage is needed in urban parameterisations. The urban MH is increased over the rural MH, as shown by several numerical schemes and careful sodar analyses. This work has been carried out within the COST-715 Action “Meteorology applied to urban air pollution problems (1998–2004). COST 715 reached a consensus proposing representatively sited measurements of meteorological parameters and turbulent fluxes above roof-tops, and recognised that such data are needed to improve numerical models of the urban surface processes.
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the surface energy balance and the Mixing Height in urban areas activities and recommendations of cost action 715
Boundary-Layer Meteorology, 2007Co-Authors: Martin Piringer, S Joffre, M. Tombrou, Alexander Baklanov, Andreas Christen, Marco Deserti, Koen Ridder, Stefan Emeis, Patrice Mestayer, D R MiddletonAbstract:The specific problems of determining and simulating the surface energy balance (SEB) and the Mixing Height (MH) over urban areas are examined. The SEB and MH are critical components of algorithms and numerical models for the urban boundary layer, though the constituent parts of the SEB and the MH are not routinely measured by national weather services. Parameterisations are thus needed in applications. In this investigation, several recently developed algorithms and models for estimating the SEB and MH were applied to new datasets and assessed. Results are discussed in terms of the need for spatial resolution and the parameters needed to describe the urban atmosphere. Limitations of models are identified and recommendations for further development and observations are given. Having identified gaps in knowledge, key findings from new urban experiments and numerical modelling for the SEB and MH are given. The diurnal cycle for the SEB is significantly different from rural conditions—urban heat storage is needed in urban parameterisations. The urban MH is increased over the rural MH, as shown by several numerical schemes and careful sodar analyses. This work has been carried out within the COST-715 Action “Meteorology applied to urban air pollution problems (1998–2004). COST 715 reached a consensus proposing representatively sited measurements of meteorological parameters and turbulent fluxes above roof-tops, and recognised that such data are needed to improve numerical models of the urban surface processes.
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the Mixing Height in urban areas comparative study for copenhagen
Atmospheric Chemistry and Physics, 2004Co-Authors: Alexander Baklanov, A KuchinAbstract:The urban boundary layer (UBL), in comparison with "rural" homogeneous atmospheric boundary layers, is characterised by greatly enhanced Mixing, resulting from both the large surface roughness and increased surface heating, and by horizontal heterogeneity of the Mixing Height (MH) and other meteorological fields due to variations in surface roughness and heating from rural to central city areas. So, the UBL is considered as a specific case of the atmospheric boundary layer (ABL) over a non-homogeneous terrain. Therefore it is important to study how much the MH characteristics differ in urban and rural, marine or other more homogeneous areas. Most of the parameterisations of MH were developed for the conditions of a homogeneous terrain, so their applicability for urban conditions should be verified. Just a few authors suggested specific methods for MH determination in urban areas. In this paper the MH over urban, semi-urban, rural and marine areas of the Copenhagen metropolitan area is considered. Proceeding from the data from the Jaegersborg radiosounding station measurement and analysis of different methods of the MH estimation, the peculiarities of the UBL and intercomparison of different MH estimation methods for urban and rural conditions are discussed. It is shown that the urban MH is considerably bigger for stably stratified (nocturnal) boundary layer cases in comparison with the "non-urban" MH. Daytime (usually the convective boundary layer) MH does not differ significatly in urban and "non-urban" sectors.
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the Mixing Height in urban areas a review
2002Co-Authors: Alexander BaklanovAbstract:The urban boundary layer (UBL), in comparison with ‘rural’ homogeneous PBLs, is characterised by greatly enhanced Mixing, resulting from both the large surface roughness and increased surface heating, and by horizontal inhomogeneity of the Mixing Height (MH) and other meteorological fields due to variations in surface roughness and heating from rural to central city areas. So, it is reasonable to consider the UBL as a specific case of the atmospheric boundary layer over a non-homogeneous terrain. Most of the parameterisations of MH were developed for the conditions of a homogeneous terrain, so their applicability for urban conditions should be verified. Just a few authors suggested specific methods for MH determination in urban areas. Some authors tested the applicability of MH methods for specific urban sites, but a comprehensive analysis of the applicability does not exist yet. Proceeding from analysis of different methods of the MH estimation for urban areas, the following preliminary suggestions are discussed. For the estimation of the daytime MH, the applicability of common methods is more acceptable than for the nocturnal MH. For the convective UBL the simple slab models were found to perform quite well. The formation of the nocturnal UBL occurs in a counteraction with the negative ‘non-urban’ surface heat fluxes and positive anthropogenic/urban heat fluxes, so the applicability of the common methods for the SBL estimation is less promising. Applicability of some newly developed methods for the SBL Height estimation, including diagnostic and prognostic equations and an improved Rimethod are also discussed.
Stefan Emeis - One of the best experts on this subject based on the ideXlab platform.
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a comparison between modelled and measured Mixing layer Height over munich
Boundary-Layer Meteorology, 2009Co-Authors: A. Dandou, M. Tombrou, Klaus Schafer, E Bossioli, Stefan Emeis, Anna P Protonotariou, Nikolaos Soulakellis, Peter SuppanAbstract:An attempt is made to correlate the Mixing Heights, derived from ceilometer and Sodar measurements, to those simulated by different atmospheric boundary-layer parameterization schemes. The comparison is performed at two sites (one suburban and one rural) close to Munich, Germany for two spring and two winter days. It is found that, under convective conditions, the Mixing Height determined, by both Sodar and ceilometer, corresponds to the middle or the top of the entrainment zone, respectively, as calculated from the eddy-viscosity profiles. Under stable conditions, the measured Mixing Height is related to the Height where eddy viscosities attain their minimum values (Sodar) or to the Height of residual mechanical turbulence (ceilometer). During a foehn case with weak turbulence, the measured Mixing Height from both Sodar and ceilometer is better inferred by considering the eddy-viscosity profiles during daytime and the Height of the low-level jet during nighttime.
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The surface energy balance and the Mixing Height in urban areas—activities and recommendations of COST-Action 715
Boundary-Layer Meteorology, 2007Co-Authors: Martin Piringer, Alexander Baklanov, Sylvain Joffre, Andreas Christen, Marco Deserti, Koen Ridder, Stefan Emeis, Patrice Mestayer, Maria Tombrou, Douglas MiddletonAbstract:The specific problems of determining and simulating the surface energy balance (SEB) and the Mixing Height (MH) over urban areas are examined. The SEB and MH are critical components of algorithms and numerical models for the urban boundary layer, though the constituent parts of the SEB and the MH are not routinely measured by national weather services. Parameterisations are thus needed in applications. In this investigation, several recently developed algorithms and models for estimating the SEB and MH were applied to new datasets and assessed. Results are discussed in terms of the need for spatial resolution and the parameters needed to describe the urban atmosphere. Limitations of models are identified and recommendations for further development and observations are given. Having identified gaps in knowledge, key findings from new urban experiments and numerical modelling for the SEB and MH are given. The diurnal cycle for the SEB is significantly different from rural conditions—urban heat storage is needed in urban parameterisations. The urban MH is increased over the rural MH, as shown by several numerical schemes and careful sodar analyses. This work has been carried out within the COST-715 Action “Meteorology applied to urban air pollution problems (1998–2004). COST 715 reached a consensus proposing representatively sited measurements of meteorological parameters and turbulent fluxes above roof-tops, and recognised that such data are needed to improve numerical models of the urban surface processes.
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the surface energy balance and the Mixing Height in urban areas activities and recommendations of cost action 715
Boundary-Layer Meteorology, 2007Co-Authors: Martin Piringer, S Joffre, M. Tombrou, Alexander Baklanov, Andreas Christen, Marco Deserti, Koen Ridder, Stefan Emeis, Patrice Mestayer, D R MiddletonAbstract:The specific problems of determining and simulating the surface energy balance (SEB) and the Mixing Height (MH) over urban areas are examined. The SEB and MH are critical components of algorithms and numerical models for the urban boundary layer, though the constituent parts of the SEB and the MH are not routinely measured by national weather services. Parameterisations are thus needed in applications. In this investigation, several recently developed algorithms and models for estimating the SEB and MH were applied to new datasets and assessed. Results are discussed in terms of the need for spatial resolution and the parameters needed to describe the urban atmosphere. Limitations of models are identified and recommendations for further development and observations are given. Having identified gaps in knowledge, key findings from new urban experiments and numerical modelling for the SEB and MH are given. The diurnal cycle for the SEB is significantly different from rural conditions—urban heat storage is needed in urban parameterisations. The urban MH is increased over the rural MH, as shown by several numerical schemes and careful sodar analyses. This work has been carried out within the COST-715 Action “Meteorology applied to urban air pollution problems (1998–2004). COST 715 reached a consensus proposing representatively sited measurements of meteorological parameters and turbulent fluxes above roof-tops, and recognised that such data are needed to improve numerical models of the urban surface processes.
M. Tombrou - One of the best experts on this subject based on the ideXlab platform.
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a comparative study and evaluation of Mixing Height estimation based on sodar rass ceilometer data and numerical model simulations
Boundary-Layer Meteorology, 2012Co-Authors: C. G. Helmis, Christoph Münkel, G Sgouros, M. Tombrou, Klaus Schafer, E Bossioli, A. DandouAbstract:A comparative study and evaluation of Mixing-layer Height estimation was conducted, using data from remote sensing and in-situ instrumentation, radiosondes, synoptic analyses and model simulations. The data were collected during an experimental campaign conducted at the Athens International Airport, Greece, from 15 to 26 September 2007. Mixing-layer Height from the sodar dataset was estimated taking into account the backscatter signal, temperature, Richardson number profiles and surface-based measurements, while for the ceilometer data, the optical attenuated aerosol backscatter intensity first derivative was utilized. Numerical simulations using the Penn State/NCAR MM5 numerical mesoscale model and the Weather Research and Forecast numerical model were also performed. Comparative results under different meteorological conditions (local flows, moderate to strong background flows) are presented and discussed. According to our results under moderate to strong winds the existing mechanical turbulence creates good signal conditions for the two remote systems leading to a good overall agreement between the two methodologies, while both models give reliable estimations of the Mixing Height. The sodar-RASS system is more suitable under low to moderate winds or when local flows are developed with weak stability, while the ceilometer system is more suitable for moderate to strong winds, which is associated with a homogeneous atmosphere and weaker low-level temperature inversions. In the models, the existing approach for atmospheric boundary-layer depth simulation usually provides higher compared to remote sensing values, especially during local flow events. An alternative approach for the estimation of Mixing Height by the models, the estimation and use of the diffusion coefficient profiles, is a promising methodology regarding the comparison with the sodar-RASS Mixing-Height estimations.
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a comparison between modelled and measured Mixing layer Height over munich
Boundary-Layer Meteorology, 2009Co-Authors: A. Dandou, M. Tombrou, Klaus Schafer, E Bossioli, Stefan Emeis, Anna P Protonotariou, Nikolaos Soulakellis, Peter SuppanAbstract:An attempt is made to correlate the Mixing Heights, derived from ceilometer and Sodar measurements, to those simulated by different atmospheric boundary-layer parameterization schemes. The comparison is performed at two sites (one suburban and one rural) close to Munich, Germany for two spring and two winter days. It is found that, under convective conditions, the Mixing Height determined, by both Sodar and ceilometer, corresponds to the middle or the top of the entrainment zone, respectively, as calculated from the eddy-viscosity profiles. Under stable conditions, the measured Mixing Height is related to the Height where eddy viscosities attain their minimum values (Sodar) or to the Height of residual mechanical turbulence (ceilometer). During a foehn case with weak turbulence, the measured Mixing Height from both Sodar and ceilometer is better inferred by considering the eddy-viscosity profiles during daytime and the Height of the low-level jet during nighttime.
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the surface energy balance and the Mixing Height in urban areas activities and recommendations of cost action 715
Boundary-Layer Meteorology, 2007Co-Authors: Martin Piringer, S Joffre, M. Tombrou, Alexander Baklanov, Andreas Christen, Marco Deserti, Koen Ridder, Stefan Emeis, Patrice Mestayer, D R MiddletonAbstract:The specific problems of determining and simulating the surface energy balance (SEB) and the Mixing Height (MH) over urban areas are examined. The SEB and MH are critical components of algorithms and numerical models for the urban boundary layer, though the constituent parts of the SEB and the MH are not routinely measured by national weather services. Parameterisations are thus needed in applications. In this investigation, several recently developed algorithms and models for estimating the SEB and MH were applied to new datasets and assessed. Results are discussed in terms of the need for spatial resolution and the parameters needed to describe the urban atmosphere. Limitations of models are identified and recommendations for further development and observations are given. Having identified gaps in knowledge, key findings from new urban experiments and numerical modelling for the SEB and MH are given. The diurnal cycle for the SEB is significantly different from rural conditions—urban heat storage is needed in urban parameterisations. The urban MH is increased over the rural MH, as shown by several numerical schemes and careful sodar analyses. This work has been carried out within the COST-715 Action “Meteorology applied to urban air pollution problems (1998–2004). COST 715 reached a consensus proposing representatively sited measurements of meteorological parameters and turbulent fluxes above roof-tops, and recognised that such data are needed to improve numerical models of the urban surface processes.
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The Importance of Mixing Height in Characterising Pollution Levels from Aerosol Optical Thickness Derived by Satellite
Water Air and Soil Pollution: Focus, 2002Co-Authors: A. Dandou, E. Bosioli, M. Tombrou, N. Sifakis, D. Paronis, N. Soulakellis, D. SarigiannisAbstract:In the present study the horizontal distribution of columnar aerosol optical thicknessderived at high spatial resolution from Earth observation satellite data in the Lombardy area (Italy) was converted to the horizontal distribution of optically effective aerosols concentration at the ground level. This was achieved by incorporating information on atmosphere's Mixing Height, at which pollutants released at ground level are vertically dispersed by convection or mechanical turbulence. The resulted fields compared favourably to pollutant concentration measurements provided by the ground stations. These results show that it is possible to calculate mean concentration fields by using the spatial distribution of aerosol optical thickness (AOT) measured by satellite normalized by the atmospheric Mixing Height. The advantage of satellites in measuring AOT is that they can capture all actual emissions compared to the models, which are based on inventoried data.