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Rodriguez Algeciras J.A.,University of Camaguey | Matzarakis A.,Research Center Human Biometeorology
International Journal of Biometeorology | Year: 2015

In order to contribute to the sustainability of the outdoor environment, knowledge about the urban thermal bioclimate should be transferred into climatic guidelines for planning. The general framework of this study responds to the need of analyzing thermal bioclimate in Mediterranean climate regions and its influence as an urban design factor. The paper analyzes the background of the urban climate and thermal bioclimate conditions in Barcelona (Spain), through the effect of shade conditions and wind speed variations. Simulations of shade and wind speed variations were performed to evaluate changes in thermal bioclimate due to modifications in urban morphology. Air temperature, relative humidity, wind speed, and solar radiation for the period from January, 2001 to January, 2015 were used to calculate physiologically equivalent temperature (PET) using the RayMan model. The results demonstrate that shade is the most important strategy to improve urban microclimatic conditions. In Barcelona, human thermal comfort conditions can be improved by shade and wind speed increase in terms of PET above 23 °C and by a wind speed decrease for thresholds of PET below 18 °C. Heat stress situations can be mitigated by shade and wind speed increase in conditions above 35 and 45 °C, respectively. The results of the study are an important contribution for urban planners, due to their possibilities and potential for the description of microclimatic conditions in Mediterranean climate regions. The knowledge is useful for improved human thermal comfort conditions, from the suitable configuration of urban form and architecture. © 2015 ISB Source

Sharmin T.,University of Cambridge | Steemers K.,University of Cambridge | Matzarakis A.,Research Center Human Biometeorology
Building and Environment | Year: 2015

The study has observed microclimatic conditions in residential, commercial and educational areas in Dhaka city. Comfort surveys were carried out along with microclimatic measurements. Findings suggest, urban forms that are more variable with irregular plot sizes and building heights, mostly in traditional areas, have positive responses with respect to the synoptic climate, while planned areas with uniform plot sizes and height, shows a tendency to develop daytime urban heat island effect. An east-west orientated street in a formal residential area was found to be 1 °C-3.8 °C warmer than a street in a traditional residential area in the same orientation. It is apparent that the differences are directly linked to the specific geometric pattern of the areas and can be defined by the parameters like uniformity versus diversity and compactness versus openness. Uniform heights, equal building separation and plot sizes can lead to harsher urban microclimate, while variety in these may foster positive changes. Lack of such variety can even affect compact urban areas. This is also evident from the analysis of pedestrian's responses in the case-study areas. Pedestrians in the formal planned areas or less diverse traditional areas were found to be less comfortable than those in the more variable areas. A statistical analysis of climatic variables and thermal sensation showed moderately strong and significant correlations. These reveal that urban geometry and the resultant climatic variables may not be the only, but one of the most important factors for governing the outdoor thermal comfort sensation in a tropical climate. © 2015 Elsevier Ltd. Source

Paparrizos S.,Albert Ludwigs University of Freiburg | Maris F.,Democritus University of Thrace | Matzarakis A.,Albert Ludwigs University of Freiburg | Matzarakis A.,Research Center Human Biometeorology
Theoretical and Applied Climatology | Year: 2016

Potential evapotranspiration (PET) is one of the most critical parameters in the research on agro-ecological systems. The computational methods for the estimation of PET vary in data demands from very simple (empirically based), requiring only information based on air temperatures, to complex ones (more physically based) that require data on radiation, relative humidity, wind speed, etc. The current research is focused on three study areas in Greece that face different climatic conditions due to their location. Twelve PET formulae were used, analyzed and inter-compared in terms of their sensitivity regarding their input coefficients for the Ardas River basin in north-eastern Greece, Sperchios River basin in Central Greece and Geropotamos River basin in South Greece. The aim was to compare all the methods and conclude to which empirical PET method(s) better represent the PET results in each area and thus should be adopted and used each time and which factors influence the results in each case. The results indicated that for the areas that face Mediterranean climatic conditions, the most appropriate method for the estimation of PET was the temperature-based, Hamon’s second version (PETHam2). Furthermore, the PETHam2 was able to estimate PET almost similarly to the average results of the 12 equations. For the Ardas River basin, the results indicated that both PETHam2 and PETHam1 can be used to estimate PET satisfactorily. Moreover, the temperature-based equations have proven to produce better results, followed by the radiation-based equations. Finally, PETASCE, which is the most commonly used PET equation, can also be applied occasionally in order to provide satisfactory results. © 2016 Springer-Verlag Wien Source

Gueguen F.,CNRS Hydrology and Geochemistry Laboratory of Strasbourg | Stille P.,CNRS Hydrology and Geochemistry Laboratory of Strasbourg | Dietze V.,Research Center Human Biometeorology | Giere R.,Albert Ludwigs University of Freiburg
Atmospheric Environment | Year: 2012

Passive air samplers have been installed in industrial, urban, rural and remote forested environments in order to collect coarse airborne particles for subsequent chemical characterization. To identify principal polluting sources, isotopic tracers, such as Sr, Nd and Pb isotopic ratios, have been used. The mass deposition rates (MDRs) of trace metals, determined for each of the studied environments, clearly indicate that industrial and traffic sites are especially affected by air pollution. Elements such as V, Pb, Fe, Cr, Co, Mo, Cd, Ni, As, Sb and Zn are notably enriched in samples from industrial zones, whereas V, Mn, Ba, Sr, Al, U, Th, rare earth elements (REE), Zr, Y, Cs, Rb, Sb, Sn and Cu are principal components of the airborne particles collected close to areas influenced by heavy traffic. The chemical/isotopic baseline composition derived from the airborne particles is the result of mixing of particles from different industrial sources, traffic and fertilizers. The monthly analysis of trace-metal MDRs of the collected airborne particle samples from different stations around the industrial zone allows for the detection of distinct atmospheric dust-deposition events during the year, characterized by high MDRs. " Natural" dusts from regional soil re-suspension, including from more distant regions like the Sahara desert, might overprint the regional atmospheric baseline composition, as suggested by trace metal trajectories in ternary diagrams and by Sr, Nd and Pb isotope data. © 2012 Elsevier Ltd. Source

Ketterer C.,Albert Ludwigs University of Freiburg | Matzarakis A.,Albert Ludwigs University of Freiburg | Matzarakis A.,Research Center Human Biometeorology
Landscape and Urban Planning | Year: 2016

The gap between point measurements made during a measurement campaign and the required discrete data of human thermal comfort in the form of maps could be overcome by statistical or numerical models. City planners usually demand thermal maps with a resolution below 50 m. The required input data for the statistical models were meteorological data at high resolution as well as land use and land cover data including morphological data. Meteorological data were obtained through car traverses on a measuring campaign on hot summer days in July 2014. The chosen statistical approaches of stepwise multiple linear regression and artificial neural network were compared for the case study area Stuttgart, Germany. The Physiologically Equivalent Temperature (PET) was applied to analyse the human thermal conditions taking into account both the meteorological environment and the thermo-physiological parameters including the human energy balance. The polycentric and complex spatial distribution of heat stress and heat load is clearly visible in the created maps. One hot spot is the city centre and its surrounding residential neighbourhood, the other hot spot can be detected in Bad Cannstatt (easterly of the Neckar river valley), including industrial and residential areas. Thereby, the non-linear artificial neural network model delivers better results than the stepwise multiple linear regression model. Advantages of the artificial neural network arise from the possibility to reveal non-linear dependencies and interactions between the variables resulting in a better model fit. © 2016 Elsevier B.V. Source

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